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Unit 1: Biology Unit Goals 1. Explore microscopy and the emergence of cell theory 2. Identify cellular structures and functions 3. Identify the role of cell membranes in active and passive transport of matter 4. Explore cell specialization in multicellular organisms (specifically plants) Topic 1: Cell Theory Intro Brainstorm: What does it mean to be a living thing? Recall: What is a cell? Salamander video Recall from Jr. High... Presently, scientists agree that all living things share five characteristics. 1. Need energy 2. Produce waste 3. Reproduce 4. Grow 5. Respond and adapt to their environment Where do maggots come from? For a long time, people believed that maggots arose spontaneously from rotting material. This theory of spontaneous generation, or abiogenesis, was widely accepted for over 2000 years. Aristotle based his “Origin of Life” theory on such observations, and never conducted any experiments to check the validity of his observations. Aristotle (~350 BCE) Observed nature directly, Classified all known organisms in either plant or animal kingdoms, plants ranking below animals in the ladder of life Observed that living organisms seemed to arise from non-living matter - process known as spontaneous generation. Francesco Redi (1668) Redi was the first person to use scientific experiments to test the theory of spontaneous generation. He suspected that the maggots that appeared on rotting meat did not actually arise from the meat itself. Redi’s Controlled Experiment Three pieces of meat... Redi’s Maggot Experiment Spontaneous vs. Non-Spontaneous Many people believed an “active principle” in the air created the microorganisms despite Redi’s evidence. For another 200 years, people debated their differing theories. Louis Pasteur (~1850) Pasteur was convinced that spontaneous generation didn’t occur - From his experiments, he was aware that small microorganisms carried out the process of fermentation. Pasteur hypothesized that the “active principle” in the air was also an organism. To test this hypothesis, he designed the swan - neck flask. Pasteur’s Controlled Experiment 1. Filled a number of “swan-neck flasks” with a nutrient rich broth and boiled them to force out air and kill all microbes. 2. As flasks cooled, fresh air was drawn in and moisture condensed on the curve of the neck. He believed that this air would contain microorganisms, but b/c of gravity they would settle in the neck and never reach the broth. 3. Several days later the broth remained clear. Therefore, his hypothesis was valid! Biogenesis: The theory that living organisms could arise only from other living organisms. This was the theory that many scientists, like Redi and Pasteur, accepted rather than that of spontaneous generation. Today, this process of eliminating bacteria from food products through the use of heat is referred to as pasteurization. Discovering Cells Scientists could only learn so much by making observations with their unaided eyes. With the advent of the microscope, scientists were able to answer many more questions about the structure of organisms. Eventually, scientists concluded that all living things are composed of cells. Developing the Cell Theory Robert Hooke (1665) Observed once-living matter through a microscope which revealed hundreds of empty box-like compartments Because these empty boxes reminded him of the rooms of the monks at the monastery, he named the structures “cells” Antony van Leeuwenhoek (1674) Studied blood cells, pond-water organisms, and matter scraped off his teeth. When viewing his tooth matter under a microscope he observed “..little living animalcules, very prettily-moving” His “animalcules” sightings were among the first observations of single-celled organisms. Schleiden and Schwann (1839) Schleiden, after great examination, concluded that all organisms are composed of cells and materials produced by cells. ➔ Observed nuclei in very young cells; concluded that new cells developed from the original cell. Schwann studied plant tissues, but after discussing his observations with Schleiden, he decided that if he too saw nuclei in animal tissues, then they must also have cells. ➔ ALL organisms contain cells Rudolf Virchow (1855) Found that bone cells could develop from cartilage cells Observed cells of unicellular organism divide under a microscope. He concluded that cells divide to produce more cells. →Where cells exist, there must have been a pre-existing cell The Cell Theory 1. The cell is the smallest functional unit of life. (van Leeuwenhoek) 2. All organisms are composed of one or more cells. (Schleiden and Schwann) 3. All cells are produced from pre-existing cells. (Virchow) NOTE: Not all cells are the same! Many different types of cells exist, each with a unique function. Cell Theory Video Levels of Cellular Organization Cells are the basic units of life, but they are composed of even smaller components called organelles. Organelles themselves are not living, but each has a specialized function which contributes to the overall functioning of the cell (e.g. the nucleus contains DNA). Cell Classification Cont. Cells can become specialized to form different tissues (e.g. cardiac muscle cells form heart tissue). Unspecialized cells are referred to as stem cells. Tissues with similar functions work together to form organs (e.g. heart tissue comprises the heart). Organs with similar functions work together to form organ systems (e.g. the heart works together with arteries & veins to form the circulatory system). Exceptions to Cell Theory Life is diverse! Not all cells follow the “rules”. Exceptions to cell theory include: 1) Viruses Although they may look like cells, and they DO contain genetic material, they cannot survive outside of a host. This is because they lack metabolic and reproductive capabilities. Therefore, they are not considered to be “living”. 2. Striated Muscle Some types of muscle cells, known as striated muscle, contain multiple nuclei. These cells are long and narrow, and are bundled together by a single membrane (rather than each having their own). 3. Fungal Hyphae Fungal hyphae are cells that make up the fruiting bodies of fungi. Like striated muscle tissue, fungal hyphae are relatively large and elongated, and contain multiple nuclei. Hyphae join together to form a continuous cytoplasm rather than discrete units. Fungi are still living cells - they just follow their own rules! This makes them incredibly interesting for scientists, and a very valuable topic of research for medicine and development 1.2 How do we study something we can’t see? We make it look bigger! Cells are very very tiny - almost all are invisible to the naked eye. In order to study them, scientists must use special tools to make them appear big enough to see in great detail. This practice is called microscopy Early Microscopes The first microscope was created by Dutch lens-maker brothers by the name of Janssen (1595) – had an objective and an eyepiece lens which could magnify to 20 times the actual size. Robert Hooke (1665) improved on this with a three-lens system that also used a light to illuminate specimens. Simple Microscopes Uses only 1 lens (similar to a magnifying glass), has only one power (usually about 6x to 10x) Compound Light Microscopes Uses 2 or more lenses placed one on top of the other, can magnify up to 2000x ➔ Total Magnification = Ocular (eyepiece) lens magnification × Objective lens magnification ➔ Ex: Ocular is 10x & Objective is 40x, calculate the total magnification = 400x Improving Microscope Technology Electron Microscopes Illuminate specimens with beams of electrons instead of a beam of light Used to view objects that are too small to see with a light microscope (provides a higher resolution) ➔ (by providing a ____higher__resolution_____ High-powered electron microscopes have recently used to obtain images of atoms! Electron Microscope Images Imaging Technology and Staining Techniques Staining Staining is the addition of a stain (coloured dye) to a sample of cells to help define certain details of specimens. The membrane of the cells pictured to the right has been stained pink. The genetic material of the cells has been stained purple. Using staining techniques, we can actually see cell division in progress! Parts of a Compound Microscope STRUCTURE FUNCTION Eye piece (Ocular lens) Observe the specimen by looking through Coarse adjustment knob Moves the stage up and down. Use only with low power. Fine adjustment knob Makes the image sharper and clearer. Use with medium and low power. Revolving nosepiece Holds(supports) the objective lenses. Body tube Supports the ocular lens. Objective lenses Different levels of magnification power (low 4x, medium 10x, high 40x) Stage Is where the slide is placed for support and viewing. Stage clips Holds the slide in place Diaphragm Regulates the amount of light passing through the stage opening. Light source Supplies the light for viewing the specimen on the slide. Arm Supports the revolving nosepiece & body tube. Used to carry the microscope. Base Supports the entire microscope and is also used when carrying the microscope. How to use a microscope 2.1 Cell Anatomy The Cell as an OPen System Cells are classified as ‘open systems’ - this means that energy and matter can enter and leave freely. In order to facilitate this movement of energy and matter cells contain specialized organelles that are essential to the processes of a functioning cell. Cell Types 1. Prokaryotes, which include only bacteria and cyanobacteria. They lack membrane bound nuclei and most of the organelles found in other cells. 2. Eukaryotes, which include the protists, fungi, plants and animals. These are cells specialized to perform particular functions All cells, whether prokaryotic or eukaryotic, have DNA as the genetic material, perform the same types of chemical reactions and they are all surrounded by an external cell membrane. 1.2.2 Animal Cell Organelles 1. Cell membrane - Flexible, semi-permeable boundary that surrounds the cell, keeping it together and controlling the movement of materials in and out of the cell. 2. Cytoplasm - The semi-fluid medium that contains the organelles and nutrients for life processes. Made of 70% water. Found outside the nucleus & inside the membrane. 3. Nucleus - Controls all cellular activities, where DNA is stored 4. Endoplasmic Reticulum (ER) - A series of interconnected tubes that branch from the nuclear membrane, forming a membrane network. Two types: smooth and rough ER Smooth ER makes lipids for delivery out of the cell Rough ER makes proteins for delivery out of the cell (“rough” because it is embedded by ribosomes, which help create proteins) 5. Ribosomes May be embedded in the rough ER or free-floating in cytoplasm Translates mRNA (modified DNA) from nucleus into sequences of amino acids(aka proteins) 6. Golgi Apparatus/Body Flat, disc-shaped sacs involved in secretion. Receives substances from the ER and packages them for transport out of the cell in small sacs called vesicles. 7. Vacuole In animal cells, they appear as several membrane-bound small storage sacs which store nutrients, cell products/waste and excess ions 8. Vesicle a small sac involved in transporting materials throughout the cell 9. Mitochondria where cellular respiration takes place; provides ATP(an energy molecule) for use by the cell Aka THE POWERHOUSE OF THE CELL 10. Lysosomes membrane-bound vesicles formed by the Golgi apparatus that hold digestive enzymes. they break down waste, large molecules, other foreign particles (i.e. bacteria and viruses) Animal Cell Adaptations Animal are adapted to perform cellular respiration, a process in which energy from glucose is broken down into ATP (performed by mitochondria) ATP is a form of energy that the organism can then use for cell growth, reproduction, and other cell processes. Plant Cell Anatomy Plants contain all of the organelles possessed by animal cells. There are, however, a few organelles that are unique to plant cells… 1) Cell Wall rigid outer portion of the cell, provides shape and support Composed of cellulose. Explains why plant cells often look ‘boxy’ under the microscope, and why plants retain their rigid structure even when dead (like wood) 2) Chloroplasts where photosynthesis takes place contain chlorophyll, a green pigment which helps absorb light from the sun 3) Vacuole Is much larger than animal vacuoles Main function is to store water and give rigidity to the plant cell. Can also store other substances Animal Cell Anatomy Plant Cell Anatomy Animal Cell Diagram Plant Cell Adaptations Plant cells are adapted to perform photosynthesis, a process in which energy from the sun is transformed into glucose. Glucose is a way to store energy which the plant can then use for growth and survival. Plant cells also have cellular adaptations which allow them to store and retain large amounts of water, an essential requirement of photosynthesis. ○ vacuoles (water storage organelles) make up more than half of most plant cells Plant Cell Diagram Topic 3: Dynamic Cells 1.3.1 Cell Membranes Materials entering or exiting a cell must cross the cell membrane Cell membranes change according to each cell’s needs The flow of matter between a cell and its environment makes it an open system Phospholipid Bilayer The main function of the cell membrane is to control the movement of substances in and out of the cell. To do this, cell membranes are composed of a double layer of phospholipids with proteins and other molecules embedded within. Thus, the cell membrane is often referred to as a phospholipid bilayer. Membrane Properties Each phospholipid molecule is composed of a head and a tail. The head is hydrophilic, or “water-loving”, while the tail is hydrophobic, or “water-fearing” As a result, these molecules arrange themselves into a double-layered membrane (the phospholipid bilayer) – with the hydrophobic tails meeting up in the inside, and the hydrophobic heads facing outward – towards the water of the cytoplasm or the environment. Fluidity Membranes are in constant motion. Membrane phospholipids and proteins are able to drift past one another, which gives the membrane fluidity and allows the cell to change shape. Proteins are able to move within the membrane and can respond to internal or external factors. This model of a mobile membrane structure is referred to as the fluid-mosaic model. The mosaic portion refers to how various proteins and structures are embedded within the membrane. The Dynamic Membrane Cell membranes contain embedded proteins, which serve to physically transport substances across the membrane and carry out chemical reactions. Think of these as little ‘doors’ across the cell membrane. Protein Membranes 1) Integral Proteins Span the lipid bilayer; are permanently embedded. 2) Peripheral Proteins Associate with the surface of the membrane; are temporarily attached. Integral protein Peripheral protein Cholesterol in Cell Membrane Cholesterol acts to maintain the fluidity of the cell membrane, thereby allowing it to maintain integrity while it changes shape. Cholesterol also reduces the permeability to the membrane to small, water-soluble solutes. Membrane Functions The cell membrane acts as a barrier to other biological and chemical entities, such as ions, viruses, and bacteria. It also acts as a selective filter, regulating the movement of certain substances. The cell membrane is therefore said to be semi-permeable (only certain substances are allowed into the cell). 3.2 Transport across CEll Membranes Because only certain substances are allowed to cross the membrane, movement across cell membranes is called selective transport. Selective transport is important in maintaining a concentration gradient. Without this selectivity, ions and other particles outside the cell would reach equilibrium with the inside, disrupting cellular activities. Equilibrium = a state of balance and stability Recall that molecules tend to move from regions of high concentration to regions of low concentration, this is called movement with or down the concentration gradient. Passive Transport The movement of molecules down a concentration gradient without an input of energy from the cell There are two main types of passive transport: 1) Diffusion (movement of solute particles from an area of high concentration to an area of low concentration; how gas exchange occurs) 2) Osmosis (movement of water molecules from an area of high concentration to an area of low concentration through a semipermeable membrane – i.e. diffusion of specifically WATER molecules and specifically through a semipermeable membrane) 3) Passive Transport Cont. Facilitated diffusion, involves the transport of substances that cannot cross the membrane by themselves by proteins. Facilitated diffusion always occurs down a concentration gradient (requiring no energy). Passive Transport - Hypotonic vs. Hypertonic If a cell is surrounded by a hypotonic solution, the concentration of solute is lower outside the cell compared to inside; thus, water will move into the cell via osmosis. If a cell is surrounded by a hypertonic solution, the concentration of solute is higher outside the cell compared to inside; thus, water will move out of the cell via osmosis. If a cell is surrounded by an isotonic solution, the concentration of solute is equal inside and outside of the cell. Lets draw it! Active Transport Occasionally, the direction of a concentration gradient is opposite to the direction in which transport is needed Active transport requires energy to occur. Materials move from an area of low concentration to high concentration E.g. plant root cells use active transport to take in minerals from the surrounding soil https://contrib.pbslearningmedia.org/WGBH/conv19/tdc02-int -membraneweb/index.html Example: The Sodium-Potassium Pump Endocytosis vs. Exocytosis Some molecules, such as cholesterol, cannot dissolve in water; diffusion is impossible for such molecules. Other molecules are too large to cross membranes even through active transport. These types of molecules require: Exocytosis to release them from the cell Endocytosis: to take them into the cell Endocytosis: The cell membrane forms a pocket around the material to be transported. The membrane folds in and encloses the item into a sphere. The sphere typically pinches off a vesicle, which transports its contents within the cell. Exocytosis: The same process, in reverse: a vesicle inside the cell approaches the cell membrane, joins with it and the contents are expelled from the cell. Pinocytosis vs. Phagocytosis Pinocytosis, or “cell drinking”, is a form of endocytosis which allows cells to obtain molecules dissolved in fluids. Phagocytosis, or “cell eating”, is a form of endocytosis which allows cells to obtain solids. Membranes at Work Semi-permeable membranes are used in many areas other than just cells. Reverse osmosis Used to purify water. In this process, water is filtered through an artificial membrane containing very fine pores. The pores are large enough to allow water to pass through. However, larger particles, such as bacteria, salts, and other dissolved molecules, cannot pass through. Pressure is used to force contaminated water through the membrane. The water collected on the other side of the membrane contains far fewer impurities than before being filtered. Membranes at Work Kidney Dialysis Blood carries oxygen, nutrients, and wastes to and from the cells of the body. Damaged kidneys do not filter the blood properly and wastes can build up to toxic, even fatal, levels. In kidney dialysis the patient’s blood is pumped through tubing made from a synthetic, semi-permeable membrane. The membrane, called dialysis tubing, is immersed in a salt solution with a concentration similar to blood, but which does not contain wastes. Pores in the tubing allow small dissolved waste molecules to diffuse out of the blood while retaining large proteins and blood cells Membranes at Work Controlled Delivery of Medications Providing the right dosage and maintaining a medication at constant levels in the body can be difficult. The medications can be placed in a flat transdermal patch that sticks to the skin. A semi-permeable membrane lining the inner surface of the patch allows the drugs to diffuse out of the patch at a slow, constant rate. Cell Surface Area to Volume Ratio 1.3.3. Cell Surface Area: Volume Ratio Cells must maintain a minimum Surface Area-to-Volume Ratio to ensure access to oxygen and nutrients. This means that cells work best when the distance over which substances must diffuse is minimized. The surface area does not increase in size proportionally with an increase in volume, therefore larger cells will have a low surface area to volume ratio. The smaller the surface area to volume ratio, the more efficient cell transport will be. A very large cell with a low surface area-to-volume ratio could starve or be poisoned by its own waste. Let’s do some math EXAMPLE Compare a cube with a side length of 1.0 cm to a cube with a side length of 4.0 cm. a) What is the surface area: volume ratio of each cube? b) Which cube would be more efficient if it was a cell? Cell Shape Certain cell shapes increase surface area-to-volume ratios. Infoldings of the membrane and elongated cell shapes produce cells with large surface areas and relatively low volumes. The higher the surface area-to-volume ratio, the more transport is possible across the cell membrane. Which cell below has a greater surface area to volume ratio? Which would be the most efficient at absorbing substances? The average surface area of the human digestive tract is about 32m2 - about the size of half of a badminton court! Why? Re-cap - SA:V ratio Topic 4: Plant Specialization 1.4.1 Cell Specialization in Plants Cells need a large surface area to exchange nutrients with their surroundings The Surface Area : Volume ratio shows how efficient cells are in performing diffusion As cells increase in size, their SA:V ratio is decreased, and they are less efficient at diffusion. In order to maximize their surface area : volume ratio, cells are limited to a certain size. In order to become larger in size, then, organisms must be multicellular. Advantages of Multicellularity Division of Labour Cells may become specialized to carry out particular functions more efficiently Size Organisms can become larger, as multiple cells work together to allow for the efficient transport & exchange of materials Interdependence If one cell dies or becomes damaged, the entire organism is not significantly impacted Brainstorm: What are some potential disadvantages of Multicellularity? PLants as Multicellular Organisms The same advantages & disadvantages of multicellularity apply to plants. Plants have evolved a number of specialized organ systems, cells & tissues to help address the challenges faced by multicellular organisms... Cell Specialization in Leaves Photosynthesis: The process used by plants to produce food(carbohydrates). Glucose: A carbohydrate that both plant cells and animal cells use as a source of energy (sugar molecule). Chloroplasts: The organelle of leaf cells where photosynthesis occurs. Chlorophyll: The pigment in the chloroplast which has the ability to harness the sun’s energy. Cuticle: A waxy substance that coats the cells to prevent evaporation of water Epidermis: The outer layer covering the top and bottom of leaves made up of epidermal cells one cell layer thick. Mostly transparent. Do not contain chloroplasts and therefore cannot perform photosynthesis Palisade Tissue Cells: Long and narrow, like columns and are packed closely together under the epidermis. Just under the leaf’s upper surface where they are exposed to sunlight striking the leaf. This is where most of the leaf’s photosynthesis occurs. Spongy tissue Cells: Layered below the palisade tissue cells Contain chloroplasts and carry out photosynthesis Round and loosely packed with many air spaces between them like a sponge Help to exchange gases and water with the environment Stomata (singular = stoma): Small openings in the lower epidermal layer Allow gases and water in and out of the leaf Most stomata are on the underside of the leaf Guard Cells: Each stoma has two guard cells surrounding it that regulate the stoma’s size. The shape of the guard cells can change to open or close the stomata Vascular Tissue Cells: Form a series of tubes that transport fluids throughout the plant. In the leaves they are visible as leaf veins. Xylem: Carries water and minerals from the roots to the leaves Phloem: Carries sugars produced by the leaves to various parts of the plant Vascular bundle: Contains Xylem and Phloem arranged together Levels of Organization in Multicellular Organisms (Recap) Cells (most basic) → tissues → Organs → organ systems (most complex) Levels of Organization in Plants Cells → e.g. the different types of cells listed previously Tissues → e.g. epidermal tissue, vascular tissue Organs → e.g. roots, stems, leaves Systems → e.g. vascular system 1.4.2 Gas Exchange in Plants Stomata allow gases to diffuse in and out of the leaf. Between the upper and lower leaf surfaces there are spaces between the cells. o Carbon dioxide, oxygen, and water vapour move by passive transport between the plant cells and the surrounding air. Photosynthetic Process 1. Air (CO2) diffuses into the stomata 2. CO2 circulates in the spaces between cells 3. CO2 diffuses down concentration gradients into the cells 4. Chloroplasts use CO2 (from atmosphere) and H2O (from roots) for photosynthesis 5. O2 (& H2O) diffuse out of cell to empty space down concentration gradients 6. O2 (& H2O) diffuses out of space through stomata into environment When Stomata are Open When Stomata are Closed Carbon dioxide can enter the Gas exchange and water leaf exchange are reduced Water and oxygen can exit Less photosynthesis occurs High rates of photosynthesis are possible The Influence of Water on Stomatal Openings Transpiration: The exhalation of water vapour from leaves - controlled by the stomata. The amount of water in the guard cells determines whether the stomata are open or closed. Water moves into and out of the guard cells by osmosis. When the pressure builds in the cells (called turgor pressure), the swollen guard cell changes shape, opening the stomata As the amount of water decreases, the cells deflate and change shape again – closing the stoma. In most plants, the stomata open during the day and close at night. However, in plants that live in dry conditions, the stomata only open at night. A plant can still dry out if its water source is depleted even though the stomata will be closed. Photosynthesis in Woody Plants In woody plants (Trees), layers of dead cork cells and waxy substances prevent direct gas exchange between the external environment and living cells of the branches and trunk. Openings called lenticels perforate the bark and allow air to diffuse through, allowing cells within the roots and stems to exchange gases with the environment. 1.4.3 Water Transport in Plants In a unicellular organism, or within individual cells, water is transported by osmosis. In a multicellular organism, like a plant, water must be transported over a longer distance using a vascular system. Vascular Tissue Cells: Form a series of tubes that transport fluids throughout the plant - In the leaves they are visible as leaf veins Xylem: Carries water and minerals from the roots to leaves Phloem: Carries sugars produced by the leaves to various parts of the plant Vascular bundle: Contains the Xylem and phloem arranged together Water Transport Starts in the Roots Water enters the cells of the root epidermis by osmosis The surface area for absorbing water and dissolved minerals from the soil is increased by hundreds of root hairs Water continues diffusing through the root tissue until it reaches the xylem. Water easily diffuses across the cell membrane, but minerals do not, therefore Root cells must use facilitated diffusion or active transport to move minerals across their membranes The solution of water and minerals that accumulates in the root xylem is called xylem sap It is then transported to the rest of the plant Recall these important properties of water: Cohesion is the tendency of water molecules to stick to other water molecules. This creates the upward pull from the tip of the leaves to the tip of the roots. A break in the water column, such as a bubble, blocks the rising xylem sap (common in the freezing winter). Adhesion is the tendency of water molecules to stick to certain surfaces. The clinging of xylem sap to the xylem walls helps to prevent the sap from falling back down to the roots as a result of gravity. Root Pressure Pushes In the roots, another force that pushes fluid upward is turgor pressure inside the root xylem. This is specifically called root pressure. Water flows in to the root, building root pressure in the xylem tissues. Adhesion of the xylem sap to the xylem vessel walls helps the fluid climb upward. Transpiration Pulls The remaining work of water transport is accomplished by pulling from above. Transpiration from leaves generates this pulling force or tension. As water is “exhaled” or evaporated from the plants leaves, cohesive forces between the water molecules cause more water to be pulled up the xylem vessels in the leaf, replacing the water that has evaporated. Like an unbroken chain, the entire column of fluid is pulled upward. (List 3) (Give 1) 1.4.4 Plant Control Systems Like animals, plants must be able to react to environmental stimuli in order to survive. Plants are able to do so through a process called tropism, or the growth of the plant in a specific direction as a result of a particular stimulus. Positive tropism = growth of a plant towards a stimulus. Negative tropism = growth of a plant away from a stimulus. Types of Tropisms Phototropism = the growth of a plant in response to light (stems typically demonstrate positive phototropism, while roots demonstrate negative phototropism) Gravitropism = the growth of a plant in response to gravity (stems demonstrate negative gravitropism, while roots demonstrate positive gravitropism) Control of Phototropism Phototropism is controlled by a type of hormone called auxin. Auxin signals the elongation or lengthening of cells along the shaded side of a stem, causing it to grow towards a light source. Nastic Response (for your interest!) Nastic response: A plant response to touch Mimosa leaves respond to touch Venus’s-flytrap closes when touched. (The results of a sudden drop in Turgor Pressure) The End! (Of the Biology unit) Unit A: Energy, Matter and Chemical Topic 1: Review of Chemistry Basics Topic 1: Review of Chemistry Basics Big Idea: How can we safely explore and apply the different properties of matter? How has our understanding of chemical substances changed over time? 1.1 Lab Safety Review What does WHMIS stand for? Workplace Hazardous Materials Information System WHMIS provides detailed information about how to store, handle, and dispose of chemicals commonly found in the workplace. It also provides first aid info Main Chemical Hazards 1) Flammability Substances that readily catch fire and burn in air. 2) Reactivity Substances that release large amounts of heat or energy. 3) Health Substances which have harmful toxic effects upon exposure. The 10 WHMIS Pictograms Explosive or Flammable Oxidizing reactivity hazard hazard Will cause death Compressed Corrosive or immediate gas toxicity with short exposure to small amounts May cause May cause May cause May cause serious health serious health serious health damage to effects, or effects effects, damageor the the aquatic (particularly damage ozone layer the environment - carcinogens) ozone layer do not dispose down drains (Material)Safety Data Sheet (SDS) These provide additional detailed information about each chemical, including its physical and chemical properties, safe handling, first aid, and disposal procedures. Lab Safety Rules For Everyone to Follow 1. Read and listen to all instructions carefully. 2. Wear goggles, gloves, aprons as required. 3. NO food or drink in the lab. 4. Tie back loose hair and roll up sleeves, no open toed shoes or shorts/ crop tops/sleeveless shirts. 5. NEVER taste anything. 6. Wash your hands after handling chemicals. 7. Report spills and accidents immediately. 8. Clarify handling and disposal procedures beforehand. 1.2: Matter & its Properties 1.2 QUICK REVIEW: What is Matter? Matter is anything with mass or volume It can exist as a solid, liquid, or gas. Matter is classified according to two main categories... Organizing Matter Levels of Matter Subatomic Particles. The charged particles and neutrons that compose an atom. Only electrons can be exchanged Atoms are the building blocks of matter. They define elemental properties. Elements are the names we give atoms with specific properties (e.g. any atom with 6 protons in its nucleus it referred to as carbon) Compounds are chemical substances in which two or more DIFFERENT elements are bound together (e.g. H2O) Molecules are groups of atoms bonded together. These may be atoms of the same element (e.g. diatomic molecules such as O 2) or atoms of different elements (e.g. one molecule of water, H 2O) Properties of Matter Physical properties describe the physical appearance and composition of a substance Physical Property Description Boiling Point/Condensation Point Temperature of boiling/condensing Melting Point/freezing point Temperature of melting/freezing Malleability Ability to be rolled into sheets without crumbling Ductility Ability to be stretched without breaking Colour Colour Solubility Ability to dissolve State Solid, liquid, gas Chemical properties describe the reactivity of a substance. Chemical Property Description Ability to burn Combustion (flame, heat, light) Flash point Temperature needed to ignite a flame Behaviour in air Tendency to degrade, react, or tarnish Reaction with water Tendency to corrode or dissolve Reaction with acids Corrosion, sometimes bubble formation Reaction to heat Tendency to melt or decompose Reaction to litmus paper Red - acid; Blue - base; No change - neutral Pure Substance or Mixture? 1.3 History and Application of Chemistry Chemistry - the Central science Chemistry was not directly studied as a distinct Western science until the late 1700s when humans started performing experiments and creating theories to explain their observations. Of course people had been making use of chemical properties of substances before then! Alchemy walked so Chemistry could run Alchemy: a pre-chemistry science that focused on studying metals with a goal of transforming properties. It was used in the Middle Ages and Renaissance where people tried to change diﬀerent metals into gold and to ﬁnd elixirs that would help extend life. Experimentation with alchemy lead to basic metallurgy, metalworking, production of inks, dyes, cosmetics, leather tanning, and the production of extracts and liquors. Indigenous Applications of Chemistry Indigenous Peoples have used chemical properties of substances for thousands of years to help preserve food, treat illness, build tools, and add colour to objects. Local plants, such as delphinium , were used to create dyes. Melted pine or spruce gum mixed with animal fat was used to create waterproofing for their canoes - this combination created a long-lasting hydrophobic layer on the wood. They used many local plants to treat illnesses like cough, fever, aches, pains, and insect bites. This understanding of the medicinal uses of plants has been adopted countless times by Western medicine, most notably in the isolation of salicin ( the active ingredient in Aspirin) from the bark of willow trees. Modern Chemistry - Atomic Theory By the 1800’s, a number of important generalizations existed which were developed from hundreds of experimental observations/theories. These generalizations are... - The total mass of a system remains constant - Elements react in definite proportions - Compounds have a definite composition no matter how they are prepared. These generalizations are still valid today. Theory #1: Democritus the Greek - 400BC All matter is made up of INDIVISIBLE PARTICLES called atomos. (Greek word for “indivisible” Each type of material is made up of a different type of atomos. This is where we get the word ATOM Theory #2: Dalton’s Billiard Ball - 1808 Billiard Ball Model DALTON’S ATOMIC THEORY 1) All matter is composed of atoms. 2) Atoms cannot be created or destroyed or divided into smaller pieces. 3) Atoms of a given element are identical, but different than atoms of other elements. 4) Atoms of different elements can combine to form compounds. 5) Chemical reactions change how atoms are grouped, but not the atoms themselves Theory #3: J.J.and William Thomson’s Raisin BUn/Plum Pudding - 1897 Raisin Bun Model J.J discovered NEGATIVELY CHARGED particles called ELECTRONS. William proposed that the atom was a large “bun” of evenly distributed positive charge with smaller negative “raisins” embedded. (actually they used plum pudding as the analogy…) These positive and negative charges seemed to ‘cancel’ each other out, making the atom neutral. Theory #4: Nuclear Theory & Rutherford's Gold Foil Experiment- 1911 Nuclear Model Rutherford conducted experiments with thin GOLD FOIL. He predicted most particles would pass straight through (because the positive charge was thought to be spread evenly throughout the atom and electrons were already known to be super tiny) BUT some particles were deflected offAlpha particle: 2 neutrons and 2 at angles. protons tightly bound together Rutherford explained his gold foil results by suggesting the atom had a POSITIVELY CHARGED CENTER called a NUCLEUS surrounded by ELECTRONS floating in empty space. Video He believed that the nucleus was thus composed of positively charged molecules called protons. To explain mass differences between H and He atoms, he hypothesized the existence of a 3rd, neutral subatomic particle the NEUTRON! - which was experimentally confirmed by Chadwick in 1932 Theory #5: Bohr’s Planetary Model - 1913 Planetary Model 1. Electrons travel in the atom in circular orbits with specific energies 2. There is a maximum number of electrons allowed in each orbit 3. Photons cause electrons to ‘jump’ to a higher level when absorbed. When an electron ‘drops’ to a lower level a photon is emitted a. these photons will emit light of very specific wavelengths that correspond to the specific energy transition involved Theory #6: Quantum Theory - 1926 Electron Cloud Model A mathematical model that describes ELECTRONS as existing in a CLOUD AROUND THE NUCLEUS Current Understanding Each atom contains a dense nucleus which carries most of an atom’s mass Positively charged particles called protons and particles with no charge called neutrons are found in the nucleus (together they are called nucleons) Small, negatively charged particles called electrons surround the atom in fixed orbitals (orbital: A 3D description of the most likely location of an electron around an atom.) Bohr Diagrams As suggested by Niels Bohr in his atomic model, electrons exist in fixed energy levels surrounding the nucleus of an atom. In a Bohr Diagram, electrons are represented as traveling in circles at these different energy levels (aka orbitals/shells). Bohr diagrams are used to predict bonding and reactivity in elements, i.e. how likely an element is to form a compound with another element. Sulphur the innermost shell/level can hold only 2 electrons The next 2 shells/level can hold up to 8 electrons the outermost shell occupied by electrons is referred to as the valence shell elements with the same number of electrons in their valence shells display similar chemical behaviours Energy Level Max. Number of Electrons 1 2 2 8 Do you notice a connection with the PT? 3 8 Bohr Diagrams (cont’d) We use the atomic number (recall that this represents the number of protons) to determine the number of electrons we need to include in the Bohr diagram - a neutral atom will have equal numbers of protons and electrons The number of protons and neutrons should be noted in the nucleus. Recall that the atomic mass is the weighted average of the nucleons (protons + neutrons), therefore the number of neutrons will be the difference between the Atomic Mass (rounded to the nearest whole number) and the Atomic Number. The most common form of Carbon (Carbon-12) therefore has 6 protons, 6 neutrons, and 6 electrons. DRAWING Bohr Diagrams Neutral atom 1. Draw the nucleus and indicate the number of protons and neutrons 2. Determine the number of electrons – will be the same as # of protons. 3. Draw a first ring to represent the first orbital/shell/energy level and draw dots to indicate up to 2 electrons together in a pair. (or on opposite sides of the nucleus) 4. Draw a second ring to represent the 2nd orbital and indicate up to 8 electrons Draw each electron one at a time in 4 quadrants and only if there are more than 5 electrons do they start to pair up (this is not always done but please do it!) 5. Repeat for the third ring if there are more than 10 electrons. The 3rd ring can hold up to 8 electrons 6. After Argon(# 18) we don’t do Bohr models in Science 10. (too complicated!) 7. Watch out for isotopes and ions! (more on this later!) Remember that you must fill one level before going on to draw the next level! Bohr Diagrams (cont’d) Bohr diagrams can also be drawn as a simplified model: Sulphur Drawing bohr Diagrams Example: Magnesium and Fluorine Consider the Bohr Consider the Bohr diagram below. What diagram below. What atom does this atom does this represent? represent? Neutrons and Isotopes The presence of neutrons also explains isotopes - atoms of the same element that have a different mass. Example: Neon-20 vs. Neon-22 Neutrons were experimentally confirmed by James Chadwick in 1932. Recall that # of neutrons = Atomic Mass - Atomic Number Example: How many of each subatomic particle are found in a) Phosphorus-33? b) Silicon-28? Ions Ions are atoms that have lost or gained electrons, resulting in either a positive (+) or negative (-) charge. Anions are negatively charged (results from a gain of electrons) Cations are positively charged (results from a loss of electrons) Ions Practice A. How many electrons are found in an ion of sodium with a charge of 1+? B. How many electrons are found in an ion of calcium with a charge of 2+? C. How many electrons are found in an ion of chlorine with a charge of 1-? D. How many electrons are found in an ion of sulphur with a charge of 2-? E. Draw a Bohr diagram of a fluoride ion (F-) and a magnesium ion (Mg2+). 1.4: Interpreting the Periodic Table 1.4 Interpreting the Periodic Table PERIOD: Horizontal rows (1-7) change from metals to non-metals. Elements are organized by increasing atomic number. GROUP/FAMILY: Vertical columns (1-18) with similar chemical properties. Organized by increasing number of valence electrons (outermost electrons) Valence Electrons Electrons are the only subatomic particle that is exchanged between two elements when they react. An element's reactivity is directly related to the number of valence electrons it holds in its outer shell. the group number tells us how many electrons are in an Lithium, for example, element’s outer shell is located in period elements in each group or “family” 2, group 1. It thus has two occupied have similar properties because energy levels, and one they have the same number of valence electron. valence electrons 1.5: Forming Ions 1.5 Forming Ions QUICK REVIEW: Atoms: neutral particles where the number of protons is equal to the number of electrons. Ions: particles where the number of protons is different from the number of electrons causing either a positive or negative charge. 1 2 13 14 15 16 17 18 The Stable Octet Rule & Ion Charges Applies to elements in the “main” 8 columns of the PT – groups 1, 2, 13, 14, 15, 16, 17, 18 (and technically, only the 2nd and 3rd periods!) Atoms are really only stable if they have 8 valence electrons – so only the noble gases are naturally stable All other atoms must gain, lose, or share electrons to be more like a noble gas and achieve a full valence shell/octet. Thus, stable atoms and ions will usually have 8 valence electrons, sharing the electron configuration of the nearest noble gas the Stable Octet Rule & Ion Charges (cont’d) When the outermost energy level is full, the atom or ion is very stable and is unlikely to react. The charge of an ion is equal to the number of electrons that were gained or lost to achieve a full outer shell /stable octet – this is of course associated with the number of electrons in the valence shell. Reactivity can often be predicted by how easy or difficult it is for an atom to gain or lose the number of electrons that will achieve a full outer shell/stable octet. Key Points: Chemical species with full energy levels are most stable and atoms achieve this by becoming ions, by gaining or losing electrons. And don’t forget: The number of protons a particle has NEVER changes, only the number of electrons. Example Energy Diagram for Sodium: Is Sodium stable? Na |2e-|8e-|1e- What could it do 11p+ to become stable? Na |2e-|8e-|1e- Na |2e-|8e- 11p+ 11p+ Atom: Na Ion: Na+ Na+ has 1 more proton (p+) than electrons (e-), giving it a charge of 1+ Practice - Valence Electrons 1 2 13 14 15 16 17 18 1) How many valence electrons does a neutral atom of lithium have? Fluorine? 2) Explain why the noble gases, such as helium & neon, are unreactive. 3) Explain why alkali metals, such as sodium & potassium, are extremely reactive. 4) Predict the charge and write the symbol for ions of the atoms H , Li, Be, B, N, O, F, Na, Mg, Al, P, S, Cl Electron Dot / Lewis Diagrams Electron dot diagrams, or “Lewis diagrams”, may be used to show the number of valence electrons an atom possesses. Elements with unpaired electrons are much more likely to react with other elements. Lewis Diagram Rules: 1) There are 4 valence orbitals (like quadrants on a compass) 2) An orbital may contain 0, 1, or 2 electrons. 3) Electrons must occupy any empty valence orbitals before forming a pair. (remember drawing your Bohr diagrams?) 4) A maximum of 2 (1st period) or 8 electrons (2nd or 3rd period) can occupy orbitals in the valence level. (we won’t draw Lewis diagrams for atoms larger than Ar in Science 10) E Dot Diagram Example: Nitrogen ATOM & ION ❏ Start by placing the first electron at the 12:00 position, and then move clockwise, placing each subsequent dot at the next position (3:00, 6:00, and 9:00). (Or use the points of a compass) ❏ Once you return to the 12:00 position, you will have to begin to double-up. ❏ Note that you cannot have more than two electrons at each position, because the valence shell can contain a maximum of eight electrons. ❏ For the ion, follow the 3 steps, then place square brackets around your diagram and indicate the overall charge just up and right of the RH bracket Practice Draw an electron dot diagram for an atom AND an ion of… 1) Beryllium 2) Sulphur 3) Argon 4) Lithium 5) Fluorine 6) Nitrogen Naming Ions Once an atom has lost or gained electrons, it is called an ‘ion’. This changes both the charge of the atom (positive/negative) and sometimes the name of the particle. Non-metals will drop the last part of their name and add ‘-ide’ to the end Ex. Chlorine that has gained 1 electron has a 1- charge, and is called chloride. Written as Cl1- or Cl- Metals will keep their same name, but will be written with the charge as well Ex. A magnesium atom that has lost two electrons is called a magnesium ion. Written as Mg2+ Energy and Dot Diagrams for Chlorine Atom and Chloride Ion 7e- sdgd 8e- 8e- 8e- 2e- 2e- Cl Cl- 17p+ 17p+ Practice Draw an electron dot / Lewis diagram and name the following atoms and ions 1. Mg2+ 2. H 3. Cl- 4. He 5. Al3+ 6. O2- 1.6: Forming Compounds 1.6 Forming Compounds Quick Terminology Recap: COMPOUND- more than 1 type of atom ATOM- tiny electrons orbiting bonded together a nucleus of protons, neutrons, (of equal mass) WHat is a Chemical Formula? A specific format to indicate the chemical proportions of atoms that make up a particular compound or molecule H2O(l) Writing States AQUEOUS Name Formula Number of Diff. Number of Atoms State Elements Carbon Dioxide CO2 (g) Nitrogen dioxide NO2 (l) Salt NaCl (aq) Sugar C6H12O6 (s) Toothpaste NaF (s) Types of Compounds All compounds are one of 2 types: IONIC MOLECULAR IONIC Compounds Contain one metal and one non-metal element. (this gets a bit more complicated later…) Valence electrons are transferred completely Good conductors of electricity. Solid at room temperature. High melting points. Crystalline shape / Crystal Lattice Often highly water soluble Molecular Compounds Introducing… Diatomic and Polyatomic Molecular Elements Contain two or more non-metals Electrons are shared, not transferred Poor conductors of electricity Soft (usually) Lower melting/boiling points (usually) Varying solubility (depends on polarity) End of Topic 1!! Jane removed these next slides… PRactice 1. Draw the full Bohr diagram (also referred to as energy level diagram) for an atom of nitrogen 2. Draw the full Bohr diagram for an atom of carbon. 3. Draw a simplified Bohr diagram for an atom of potassium. 4. Draw a simplified Bohr diagram for an atom of phosphorus. Topic 2: Naming and Identifying Compounds Quick Recap: Molecular and Ionic Compounds Electron distribution Example Forms between... electrons are IONIC metal & transferred from non-metal metal to non-metal (can also involve polyatomic ions) MOLECULAR electrons are two non-metals shared between atoms Recap Cont’D.: Atoms and Compounds How many atoms are in the following compounds? N2 S8 Al(OH)3 Zn(NO3)2 Diatomic Molecules - The ‘Hockey Stick’ Diatomic = 2 (di) atoms Certain elements will always bond together in pairs, so both atoms have full valence shells and are far more stable. There are 7 key elements that are found almost exclusively in a diatomic state – all seven of these elements exist in a gaseous state. (H2, N2, O2, F2, Cl2, Br2, I2) The other 2 common polyatomic molecules are P4 and S8 When writing reactions, these elements must ALWAYS be written as a polyatomic molecule 2.1 Naming Ionic Compounds 2.1 Naming Ionic Compounds An ionic compound is made of two ions with opposing charges. This could be a metal ion (cation +) and a non-metal (anion -) or a polyatomic cation or anion with another ion of opposite charge. When added together, positive and negative ions must equal a net charge of zero to form a true compound. Balancing Charges When forming compounds, ions will pair up with each other in certain ratios that we can determine using their ion charges. Example: Sodium ion (Na+) and chloride ion (Cl-) A sodium ion has a charge of +1, and a chloride ion has a charge of -1. When they pair up, these charges cancel out, so they form a pair in a 1:1 ratio: Na+ + Cl- → NaCl PRACTICE Lithium and chlorine Balancing ShortCut - Swap the Charges REMEMBER TO REDUCE TO THE LOWEST RATIO! Practice Find the ratio needed to bond the following elements: 1. Lithium and Fluorine 2. Potassium and Nitrogen 3. Magnesium and Oxygen 4. Aluminium and Chlorine WRiting and Naming Ionic Compounds There are 3 main rules when naming and writing formulas for binary ionic compounds (compounds made from only 2 elements): 1. The first element in the name and formula must be the metal. It keeps its normal element name. 2. The second element in the name and formula must be the non-metal. It is named as an ion (the ending is modified to end in -ide). 3. The chemical formula must be balanced with the simplest whole numbers in order to achieve a net charge of zero. Practice Write the names of each of these ionic compounds: 1. Ca3P2 2. CuF2 3. BeSe 4. AlCl3 Write the formulas of these ionic compounds: 1. Potassium phosphide 2. Sodium sulfide 3. Gallium oxide 4. Strontium nitride Ain’t No Such Thing as an Ionic MOlecule!! Note that ionic compounds form crystal lattices and their formulas do NOT represent molecules. Instead, the formulas represent the smallest repeating unit within the lattice. The individual units are known as Formula Units. 2.2 Writing and Naming MOlecular Compounds 2.2 WRiting and Naming Molecular Compounds Unlike ionic compounds, molecular compounds are not balanced based on their charges. Example: CO2 Why don't we use charges for molecular compounds? To name molecular compounds, a PREFIX is used to indicate how many of each element is present. CO2 = Carbon dioxide # of Atoms Prefix # of Atoms Prefix 1 Mono 6 Hexa 2 Di 7 Hepta 3 Tri 8 Octa 4 Tetra 9 Nona 5 Penta 10 Deca Note: The prefix MONO is only used on the second element, never the first. Example: CO = Carbon monoxide Writing Molecular Formulas If we are given the name of a molecular compound, it is easy to determine the chemical formula because the prefixes tell us how many of each atom is present. For example: carbon difluoride = 1 carbon, 2 fluorine = CF2 Practice Write the names of the following formulas: 1. N 2O 2. CCl4 3. P3Cl8 Write the formulas of the following compounds: 1. Dibromine tetrachloride 2. Hydrogen pentafluoride 3. Tribromine monophosphide 2.3 Special Ionic Compounds 2.3A Multivalent Ions Because some transition metals have more than 1 possible charge (referred to as “multivalent”), we must indicate which ion is present in the compound using Roman numerals after the name of the metal. Examples: Copper, Nickel, Cobalt, Iron, Manganese, etc. Only one charge can be used, and it must be the one that results in a balanced (neutral) compound. Example: FeCl3 = Iron (III) chloride PRACTICE FeI3 PbO2 Check the possible charges of the metallic element and FeCl3 determine which charge allows for a neutral compound. Ni2S3 CuF2 Mn3O4 2.3B - Polyatomic Ionic Compounds The elements in certain polyatomic ions will always stay together when forming compounds. These can be found in a table at the top of your periodic table. Writing and Naming Polyatomic Ionic Compounds Because the atoms in a polyatomic ion always stick together, we treat the overall ion as a single unit when balancing charges, and we do not change the name. General rules: 1. Balance the charges as normal, but keep the polyatomic ion together, and add brackets if more than one ion is required. 2. When naming, use the full name of the polyatomic ion. Example: Mg(NO3)2 = magnesium nitrate Practice Use the table in your periodic table to name the following: 1. Al2(SO3)3 2. Na2SO4 3. Ca3(PO4)2 4. KMnO4 Use the table in your periodic table to write formulas for the following: 1. Ammonium phosphate 2. Potassium hydroxide 3. Magnesium phosphate 4. Beryllium silicate Common Substances You Need to Know! You are expected to know the names and chemical formulae of the following substances: Table salt - NaCl - sodium chloride Water - H2O Glucose - C6H12O6 Ammonia - NH3 Methane - CH4 2.4 Acids and Bases Acids Are molecular compounds that combine with water to produce H+ ions and an anion. They form an aqueous solution with a pH lower than 7. Bases IONIC compounds that combine with water to produce OH- ions, forming a solution with a pH greater than 7. Properties of Acids vs. Bases ACIDS BASES Form H+ ions in solution (Arrhenius’ Form OH- ions in solution definition) (Arrhenius’ definition) pH 0-6.9 pH 7.1-14 good conductors of electricity good conductors of electricity sour taste bitter taste Commonly found in foods Commonly found in cleaners turn litmus paper red turn litmus paper blue Recall - What is an indicator? Indicator: Common Indicators: Litmus Phenolphtalein pH paper Turns pink in basic solutions! pH scale The relative acidity/basicity of a substance can be determined using the pH scale. pH stands for “power of hydrogen”. Every change on the pH scale is a change of TEN TIMES. A pH of 1 is 10 times more acidic than a pH of 2. A pH of 1 is 1000 times more acidic than a pH of 4. Neutralization If acids form H+ in solution, and bases form OH-, what happens when we combine an acid & a base? H+ (aq) + OH- (aq) → H2O (l) When we combine equal amounts of an acid and a base of the same strength, the result is the formation of water. This process is referred to as neutralization. Naming Acids and Bases Remember that an acid is deﬁned as a substance that produces hydrogen ions (H+) when combined with water and a base is a substance that produces hydroxide ions (OH-) when combined with water. This means that chemical formulas that begin with hydrogen very often represent acids and formulas that end in hydroxide very often represents bases. Example : Acid - HCl(aq) , H 2SO4(aq)| Base - NaOH(aq) , Mg(OH)2(aq) Acids Although acids are technically molecular compounds, their common names are obtained via rules based on the ionic naming conventions. There are 3 rules that apply based on the “ionic name.” When writing the formula of ANY acid, it must be followed by the state notation (aq). E.g. H2S(aq) → aqueous hydrogen sulfide → hydrosulfuric acid. E.g. H2SO4(aq)→ aqueous hydrogen sulfate → sulfuric acid. E.g. H2SO3(aq) →aqueous hydrogen sulfite → sulfurous acid. Acids are often named according to more than one system… Chemical Formula “Ionic” Name Classical Naming or IUPAC Naming “Common Name” H2SO4 (aq) Hydrogen sulfate Sulfuric acid aqueous hydrogen sulfate H3PO4 (aq) Hydrogen phosphate Phosphoric acid aqueous hydrogen phosphate HCl (aq) Hydrogen chloride Hydrochloric acid aqueous hydrogen chloride HNO3 (aq) Hydrogen nitrate Nitric acid aqueous hydrogen nitrate Practice Write the formula for the following acids: 1. Nitric acid 2. Iodic acid 3. Aqueous hydrogen nitrite 4. Hydroiodic acid Practice Cont. Write the IUPAC and common names for the following acids: 1. H3PO4(aq) 2. H3BO3(aq) 3. HIO2(aq) 4. H2CrO4(aq) Naming Bases Bases are simply named as a polyatomic ionic compound… Chemical Formula Name as an Ionic Compound NaOH (aq) Sodium hydroxide Ba(OH)2 (aq) Barium hydroxide Practice Write the formula for the following bases: 1. Ammonium hydroxide 2. Sodium hydroxide 3. Magnesium hydroxide Did you remember to 4. Potassium hydroxide indicate the state?? Practice Identify each of these substances as acidic or basic and write the name: 1. H2CO3(aq) 2. LiOH(aq) 3. HNO2(aq) 4. HF(aq) Topic 3: Chemical Reactions 3.1 Properties of Water 3.1 Properties of Water The properties of water don’t seem unusual to most people because we interact with it daily. Water is essential to life on Earth. We also need water to live as we would die without it in about two days. We are also made up of about 60-75% water, so without it, we wouldn’t exist. The unique properties of water are vital to all life on Earth. DEMO - Ice Cubes and Oil Cubes Predictions: What will happen to the solid butter and solid oil when we put it in the liquids? WAter is POlar Molecular Features A molecule of water has a Bent or V-Shape due to 2 lone pairs of electrons on the oxygen atom Oxygen has a greater ability to attract electrons (this is called electronegativity - more in C20!) ⧫Oxygen atom ends up with a slightly negative charge (δ–) ⧫Hydrogen atoms end up with a slightly positive charge (δ+) The V-Shape of water allows the oxygen to “stick out,” ⧫Together with the electronegativity difference, this makes water POLAR Attraction between Water Molecules Polar molecules are attracted to other polar molecules ○ The slightly negative O atoms are attracted to the slightly positive H atoms This attraction is called an intermolecular force (vs. intramolecular force - the covalent O-H bonds) and is quite strong. The strength of these intramolecular forces between the adjacent water molecules explains the unique and important properties of water Unique Properties of Water Property Resulting Phenomena Beading of water Some insects can walk on water Strong · Only substance on Earth to exist in (surface tension) high surface tension of water ke intermolecular all three states (s), (l), (g) molecules banded together forces due to · High Boiling Point & Melting Point polarity of (relative to similar mass molecules) molecule: · High surface tension Positive H atoms are attracted to · Very effective solvent (able to and align with dissolve most things) negative O atoms · Exhibits capillary action, cohesive, adhesive forces Capillary action - attractive adhesive forces to other different molecules lets water “climb” Unique Properties of Water Property Resulting Phenomena High Specific Huge impact on climate & Heat weather next to bodies of Capacity: water and globally Involves a High melting and boiling great deal of points energy for water to cool down or warm up Unique Properties of Water Property Resulting Phenomena Water solidifies Ice floats in liquid water into a crystal network – ice is Fish stay near the bottom of lakes in the winter, where water is warm less dense Bodies of water don’t freeze than liquid completely – water near water b/c bottom is kept warm polar molecules are pushed apart Ice floats in the ocean Water as a Solvent Vocabulary Recap Solvent: Any liquid with the ability to dissolve other substances Water is frequently used as the solvent in chemical solutions due to the properties we discussed. All solutions are referred to as having an aqueous state because of this. Solute: The substance that is dissolved in a solution Solution: A homogeneous mixture of two or more substances Water is an essential part of life In addition to transporting substances, water is essential for cellular activity in most living organisms. The adult human body is composed of ~70% water; many plants near 95% water Metabolic activities require the constant balance of water consumption, retention, and loss 3.2 Chemical Reactions 3.2 What is a Chemical Reaction? A chemical reaction occurs when one or more substances react to form products with different chemical properties. A chemical reaction is also known as chemical change. Every chemical reaction can be represented using a chemical equation: Example: Baking soda (sodium bicarbonate) reacts with vinegar (acetic acid) to produce sodium acetate, liquid water, and carbon dioxide gas REACTANTS PRODUCTS Evidence of Chemical Change ❏ Change in energy (i.e. temperature) ❏ Formation of a precipitate (solid) or gas (bubbles) ❏ Change in colour or odor ❏ Change in pH A change in state (solid to liquid for example) is not an indicator of chemical change Recall: a precipitate is an insoluble solid substance formed in a reaction that occurs in solution Predicting Solubility Solubility is the ability to dissolve a solute in a solvent. ○ Saturated: maximum concentration, nothing else will dissolve. ○ Unsaturated: further solute can be added General Solubilities in Water Solids ○ Higher solubility at higher temperatures. Gases ○ Higher solubility at lower temperatures. Liquids ○ Difficult to generalize. Elements ○ Low solubility in water. Predicting Solubility A solubility table can be used to predict whether two substances will react to form a precipitate or whether they will dissolve when combined. 1. Begin with an ionic compound 2. Locate one of the ions in the top row (usually the anion) 3. Looking down the corresponding column, locate the other ion (The ion could be identified in a grouping “all” or “most”) 4. Looking across the row identify if the second ion is in the “high solubility” row or the “low solubility” row “High Solubility” = No precipitate formed = Aqueous(aq) “Low Solubility” = Yes precipitate formed = Solid(s) Solubility Table EXAMPLE 1) A chemist mixes a solution of lead nitrate, Pb(NO3)2 and potassium iodide, KI. Does a precipitate form? If so, predict the precipitate. Pb(NO3)2 dissociates to form Pb2+ and NO3- KI dissociates to form K+ and I- Possible combinations of these ions include: Pb(NO3)2 KI KNO3 PbI2 According to the chart, Pb2+ would be insoluble if with I-. Therefore, a precipitate of PbI2(s) will form when these two solutions are mixed. KNO3 is soluble in water, so its state would be (aq) We can also use the solubility table to predict whether or not an ionic compound will be soluble in water... EXAMPLE 2) Will the compound Ba(OH)2 dissolve in water? Locate OH- on the solubility table Look down the column to locate Ba2+ Because Ba2+ has high solubility with OH-, Ba(OH)2 will be soluble in water → Ba(OH)2 (aq) Practice 3) Determine whether each of the following compounds will react to form a precipitate. If yes, write out the precipitate with the appropriate notation: a. NaOH + CaCl2 b. CuCl2 + Al2S3 4) Determine whether each of the following compounds will dissolve in water: a. Magnesium sulfide b. Zinc nitrate Energy Change - Exothermic Reactions All chemical reactions either release or absorb energy Reactions that release energy are referred to as exothermic. ○ E.g. cellular respiration, combustion ○ Temperature of surroundings increases Energy Change - Endothermic Reactions Reactions that absorb energy are referred to as endothermic. ○ E.g. photosynthesis, cold packs ○ Temperature of surroundings decreases Energy Change Law of Conservation of Energy The Law of Conservation of Energy states that energy cannot be created or destroyed, only transformed from one form to another. This means that in a chemical reaction, the total energy of the reactants must be equal to the total energy of the product Example: Hydrocarbon Combustion In a hydrocarbon combustion reaction, for example, some of the initial chemical energy stored in the bonds of the fuel (methane, CH4) is released as thermal energy However, energy is not “destroyed”; it is converted from one form to another through a chemical reaction - much of the remaining energy is stored in the bonds of the newly formed compounds. + HEAT!! Law of Conservation of Mass During a chemical reaction, the total mass of the reacting substances must also equal the total mass of the resulting substances This is called “Lavoisier's Law” This allows us to predict the mass of reactants required to produce a known quantity of products. PRACTICE Consider the following reaction: Na(s) + Cl2 (g) → NaCl(s) What mass of chlorine gas must react with 30g of sodium to produce 50g of sodium chloride? Law of Conservation of Mass Another implication of Lavoisier’s Law is that you must have the same number of each type of atom on each side of the equation, as matter cannot be created or destroyed. Balancing Chemical Equations Due to the law of conservation of mass, chemical equations must be balanced in order to be properly written. Writing Chemical Equations Chemical equations can be written in three different formats 1) Word Equation (names of products & reactants) solid sodium + chlorine gas → solid sodium chloride 2) Skeleton Equation (chemical formulas of products and reactants) Na(s) + Cl2(g) → NaCl (s) 3) Balanced Chemical Equation (Skeleton equation plus coefficients that follow the Law of Conservation of Mass) 2 Na(s) + 1 Cl2(g) → 2 NaCl (s) Balancing Chemical Equations Due to the law of conservation of mass, chemical equations must be Balanced in order to be properly written. E.g. Hydrogen gas combines with oxygen gas to form water vapour. 1. Word equation: hydrogen gas + oxygen gas → water vapour 2. Skeleton Equation: Write an equation by replacing the words with chemical formulas Be sure to have the correct formulas for all compounds and elements. Each reactant and product make up a “term” in the equation H2(g) + O2(g) → H2O(g) This does NOT follow the Law of Cons of Mass! Balancing Chemical Equations 3. Balanced chemical equations: The same number of atoms of each element must be present on each side of the chemical reaction **Note: The subscriptssubscripts cannot be changed in a chemical reaction! Numerical Coefficients: indicate how many of each chemical species must be present in order for the reaction to occur and are added before chemical formulas where necessary to balance the equation. Add coefficients one at a time! First … we need another oxygen molecule on the right side We must add the coefficient ___ before the H2O H2(g) + O2(g) → 2 H2O(g) Balancing Chemical Equations Second … we need 2 more hydrogen molecules on the left So we must add the coefficient 2 before the H2 2 H2 + O2 → 2 H 2O Now it is balanced! (Third: But check it!) 2 H2 + O2 → 2 H 2O Or 2 H2 + 1 O2 → 2 H 2O Recap: Balancing Chemical Equations 1. Skeleton equation - do you have the correct chemical formulas? 2. Balancing - Identify unbalanced atoms and polyatomic ions 3. Write coefficients to balance them o Begin with the more complex polyatomic ions o Work with only one atom or polyatomic ion at a time o Leave atoms that appear as elements until last o Use fractional coefficients if necessary o Clear any fractional coefficients at the end by multiplying the whole equation by the GCF 4. Check it - Make a table of the atoms for the reactants and products and check that equation is balanced Practice 1. _____ Na(s) + _____ Cl2 (g) → _____ NaCl(s) 2. _____ K(s) + _____ O2(g) → _____ K2O(s) 3. _____ CuO(s) → _____ Cu(s) + _____ O2(g) 4. _____ N2 (g) + _____ O2 (g) → _____ NO2 (g) 5. _____ BN(s) + _____ Cl2 (g) → _____ BCl3 (g) + _____ N2(g Practice A. _____ (NH4)3PO4(aq) + _____ CaBr2(aq) → ______ Ca3(PO4)2(s) + _____ NH4Br(aq) B. _____ Li(s) + _____ H2O (l) → _____ LiOH(s) + _____ H2(g) C. _____ HCl(aq) + ______ Ca(OH)2(aq) → ______ H2O(l) + ______ CaCl2(aq) D. _____ Cu(s) + _____ AgNO3(aq) → _____ Cu(NO3)2 (aq) + _____ Ag(s) E. ___ CH3COOH(aq) + ___ Ba(OH)2(aq) → ____ H2O(l) + ____ Ba(CH3COO)2(aq) Practice Use the following word equations to write & balance the correct formula equation (don’t forget the rules for naming ionic & molecular compounds!) 1. Nitrogen gas reacts with hydrogen gas to produce ammonia gas. 2. Solid potassium chlorate decomposes into oxygen gas and solid potassium chloride. 3. Solid aluminum oxide is decomposed into solid aluminum and oxygen gas. 4. Aqueous cobalt (III) nitrate reacts with solid zinc to produce aqueous zinc nitrate and solid cobalt. 3.3 Types of Chemical Reactions 3.3 Types of Chemical Reactions Classifying reactions makes it easier to predict the products of reactions and recognise new reactions. You already know how to classify reactions as endothermic or exothermic but there are other ways for reactions to be classified. We will study 5 general types of chemical reactions: 1. Formation (aka synthesis) 2. Decomposition 3. Single replacement 4. Double replacement 5. Hydrocarbon combustion Formation Reactions Two or more elements combine to form a new compound (either molecular or ionic) 2 Mg(s) + O2(g) -> 2MgO(s) Decomposition Reactions A compound is broken down into its individual elements: 2H2O(l) → 2H2(g) + O2(g) Example: Genie in a Bottle Maybe a better video? Or a real demo? Single & Double Replacement Reactions Single replacement: In a reaction between a compound and a lone element, one element in the compound is replaced by the lone element CuCl2 + Zn → ZnCl2 + Cu Double replacement: In a reaction between two compounds, one element in each compound is “swapped” with another element in the other compound HCl + NaOH → NaCl + H2O Hydrocarbon Combustion Reactions A complete hydrocarbon combustion reaction is the burning of a hydrocarbon or carbohydrate with oxygen to produce water vapour and carbon dioxide gas. Hydrocarbon Combustion Demonstration Products of Hydrocarbon Combustion PracticE Name the Reaction type, Write Missing Balanced or Word Equation 1. 2KBr(s) → 2K(s) + Br2(l) 2. 6K (s) + N2(g) → 2K3N(s) 3. Magnesium oxide → magnesium and oxygen 4. Methane and oxygen → carbon dioxide and water vapour Topic 1: Thermal Energy Topic 1: Energy and work 1.1 Energy and Technology What is Energy? What is Technology? Energy & Work Energy comes in different forms, and it is the ability to perform WORK. - What types of energy can you think of? Technology offers solutions to practical problems that arise from human needs, often by using or transforming energy. Major Human Technologies: The Steam Engine The Steam Engine is an example of technology that harnesses ENERGY to make WORK easier to do. The Steam Engine has historical importance, and is also an example of how technology evolves over time to better meet human needs. 1.2 Energy as the Ability to do Work Energy is simply the ability to do work. If an object has energy, then it can do work by transferring that energy to another object (ΔE = W). Work is the transfer of mechanical energy from one object to another. Since the transfer or change in energy is equivalent to the amount of work done on an object, both work and energy are measured in Joules (J) Types of Energy 1) Chemical energy 2) Electrical energy & magnetism 3) Nuclear & solar energy 4) Kinetic energy 5) Potential energy 6) Heat/Thermal energy Note that the amount of kinetic & potential energy possessed by an object is collectively referred to as its “mechanical” energy. 3 Conditions of Work There are 3 conditions that need to be met before we can say that work has been done. These are: 1. There must be movement ○ Ex. you can push as hard as you want on a brick wall, if the wall doesn’t move, even though force has been applied, no work has been done. 2. There must be a force ○ Ex. Coasting on a bicycle is not considered work because, even though there is movement, there is no force being applied to the pedals. 3. The force and the distance the object travels must be at least partially in the same direction ○ Ex. If you carry a bag parallel to the ground and walk forwards, this is not considered work because the force exerted on the bag for you to hold it off the ground is upwards/vertical, while it is moving with you in a forwards/horizontal direction. What is Force? Force is defined as a push or a pull on an object. An object has many forces acting upon it; the sum of these forces is referred to as net force. Objects at rest do not move because all forces acting on them are balanced. If forces become unbalanced (if one force is greater than another), then an object can gain motion. This balance is described by Newton’s First Law of Motion: An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. Inertia video of water balloon Newton’s first law explains why a space probe requires no engines to travel beyond the solar system. In deep space, there is no friction to slow things down, so the probe simply maintains its initial velocity. Using Energy to Calculate Work Energy = Work WORK can be measured quantitatively: Practice - Use the GRASP Method! 1. You exert a force of 25 N on your textbook while lifting it a height of 1.4 m to put it on a shelf. How much work did you do on your textbook? 2. If the steam from an engine does 102.5 J of work, propelling an object a distance of 26 m, what force was exerted on that object by the steam? 3. How much force is required to perform 18.0 J of work on a cart over a distance of 3.0 m? Solving Work Problems Graphically Demonstrating work graphically can help you to visualize problems in a different way. By plotting Position (distance) on the x-axis and Force on the y-axis we can calculate work by finding the area Example: This can be done for many shapes of graphs, including triangles and composite shapes. Remember: Area of a square = l x w Area of a triangle = ½ (b x h) Example: Practice What if the shape is non-uniform? For non-uniform shaped graphs, we can still estimate the amount of work done by calculating the work for a single unit, and then counting the approximate number of units Example: Practice 1.3 Work and Kinetic Energy As with the steam engine, much of human technology has been dependent on the transfer of thermal energy. - Thermal energy has been used historically even in the absence of “fancy” technology. - Cooking food over the fire (basic human necessity) - The Steam Engine was a technological solution that practically revolutionized human way of life by harnessing the power thermal energy transfer. - A Steam Engine is any machine that generates steam and converts the steam pressure into mechanical motion. What is Kinetic Energy? The degree of warmth of a substance is directly related to the kinetic energy of its individual molecules. - Heat is not an actual substance itself, it is the transfer of thermal kinetic energy from one molecule to another molecule of a substance. - More heat implies more kinetic energy because particles are colliding with each other more frequently. Thermal Kinetic Energy = Energy of Motion = Heat Heat vs Work HEAT is the mechanism of THERMAL ENERGY transfer which is directly related to the kinetic energy of particles in motion, and measured by TEMPERATURE. WORK is the mechanism of KINETIC/MECHANICAL ENERGY transfer which is measured according to FORCE and DISTANCE TRAVELLED. Calculating Kinetic Energy Any object in motion is said to have kinetic energy. The amount of kinetic energy an object has is dependent on its mass as well as the speed at which it is travelling You will need to be able to rearrange this formula and solve for the 3 variables! Practice 1. A car with a mass of 1500 kg is moving at a speed of 14 m/s. What is the kinetic energy of the car? 2. A hockey puck has a mass of 0.21 kg. If the hockey puck has 73 J of kinetic energy, how fast is it moving? 3. An object moves at a speed of 12 km/h. What is the object’s mass if it has 25 J of kinetic energy? 1.4 Potential Energy Potential energy is simply energy that has been stored in some way. There are four general types of potential energy: 1) Elastic potential energy 2) Chemical potential energy 3) Nuclear potential energy 4) Gravitational potential energy Calculating Gravitational Potential Energy The energy an object has when held at a position above the ground is referred to as its gravitational potential energy. Although the object may not be moving, it has the potential to gain kinetic energy due to the force of gravity pulling down on it. Thus, gravitational potential energy is inﬂuenced by both the force of gravity and the mass of a given object. Practice 1) A picture with a mass of 3.8 kg hangs on a wall 2.1 m above the ﬂoor. What is the gravitational potential energy of the picture relative to the ﬂoor? 2. While swinging on a playground swing, a child reaches a height of 2.8 m above the ground. If the child has 604 J of potential energy at her highest point, what is her mass? 3. An object with a mass of 5.2 kg sits on a table. If the object has a gravitational potential energy of 80.3 J, how tall must the table be? 1.5 Mechanical Energy Em = E k + E p As noted earlier, mechanical energy represents the combined amount of KINETIC and GRAVITATIONAL POTENTIAL ENERGY possessed by an object What happens to the kinetic energy of an object as its gravitational potential energy increases? What happens to the gravitational potential energy of an object as its kinetic energy increases? Example A 0.300 kg baseball is thrown in a straight line through the air. As it is released at a height of 2.50 m above the surface of the Earth, the ball has a speed of 20.0 m/s. What is the total mechanical energy of the baseball at this moment in time? 1.6 Law of Conservation of Energy Although the kinetic & gravitational potential energy possessed by an object may change depending on the situation, the total mechanical energy possessed by that object remains the same. (we ignore effects of friction, etc until higher level courses!) This “equilibrium” state of Ep and Ek is referred to as the Law of Conservation of Energy Ek ⇋ E p Note that the Law of Conservation of Energy is essentially an implication of the First Law of Thermodynamics (energy cannot be created or destroyed) Example 1) A 1.50 kg rock is dropped over the edge of a cliﬀ, 30.0 m above the surface of a lake. What is the speed of the rock just before it strikes the surface of the lake? 2. A 10.0 kg water balloon is dropped from a height of 12.0 m. Calculate the speed of the balloon just before it hits the ground. 3. A 30.0 kg child on a trampoline jumps vertically into the air at an initial speed of 1.60 ms. Calculate how high the child will rise. Jane Removed the slides after this one! Explore Activity - The Steam Engine Work with your group to share textbooks Refer to pages 142 - 147 of your Textbook. Objective: Explore to understand the historical development of the Steam Engine. Use the provided outline in your notes to record information about the Steam Engine from the textbook. Your notes should address the following scientists: Hero, Savery, Newcomen, Watt, and Parsons Topic 2: Energy of Motion 2.1 Motion Question - How do we know if something is in motion? MOTION IS RELATIVE - Inertial Frame of Reference (Perspective) Motion involves any change in position over a period of time. Types of Motion (examples, but not limited to): Linear Rotational Oscillatory Vibrational Communicating Motion There are 2 main quantities used to describe motion: Scalars = Quantities that describe magnitude (size Click on image for video or amount) but NOT DIRECTION I.e. distance; speed Vectors = Quantities that describe magnitude AND direction I.e. velocity; displacement Writing Scalars and Vectors Vectors include an arrow above the letter and scalars don’t. Ex. Velocity ( ) and speed ( v ) Vector Scalar 2.2 Distance and Displacement Distance (Scalar) Displacement (Vector) Describes the length of a Describes the straight-line path between two points or distance from one point to locations another AND direction Symbol = _________ Symbol = _______ ○ Change in “d” refers to ○ Displacement is the the change in location change in position of an object when it moves from one point to another. NOTE: Position Describes a specific point relative to a reference point which INCLUDES direction Example of Distance versus Displacement: Edmonton to Peace River Need to fix vector symbols Distance: Δd = 485 km ( on roads) Displacement: Δ⇀d = 365 km[N40°W] (as the crow flies) CALCULATING Distance & Displacement DISTANCE The DISTANCE travelled by something in motion is the SUM of the lengths of a path between two points or locations. - Simply put: ADD UP the lengths of distances travelled. - DIRECTION is not relevant when calculating distance because distance is a SCALAR quantity of motion. CALCULATING Distance & Displacement Displacement 1) Displacement in ONE DIMENSION involves motion along a straight line. 2) Describing Direction: a) Compass Directions: North (N), South (S), East (E) or West (W) b) Positive/Negative signs (+ / - ) i) In one-dimension, N-S and E-W can be forms of positive and negative descriptions. c) It is important to identify the REFERENCE POINT 3) Calculating Displacement = algebraically adding/subtracting the magnitudes of motion Calculating Displacement Δd = (dﬁnal - dinitial) Δd → displacement d initial → initial start position d ﬁnal → ﬁnal end position Units → metres (m) Expressing Directions of Vectors - Using a Compass A common method for determining direction of displacement is known as the Navigator Method. For the vector shown, north can be considered to be the beginning and is assigned an angle of 0° As you move clockwise, the angles increase. E.g. The direction of Vector A is 30° East of North BUT you could also start at East and call this Direction [60° N of E] ] Expressing Directions of Vectors - Cartesian Method Another method for determining direction of displacement is known as the Cartesian or Polar Coordinates Method. Horizontal and right is considered to be the beginning and is assigned an angle of 0° As you move CounterClockwise the angles increase. E.g. The direction of Vector A is [30°] The highest angle you will see is 360° Practice An airplane reports its ﬂight direction as [235°]. Which vector diagram correctly represents the plane’s direction? How would this direction be expressed using the Navigator Method? Caculation Example 1: Example 2: Example 3: Example 4: Jasmine walks from the back of the classroom to the front. The room has a length of 20 metres. a. What is the distance Jasmine walked? b. What is the displacement of Jasmine from start to ﬁnish? c. Now Jasmine walks half way back. What is her new total distance walked? d. What is her new total displacement? Example 5: Jacob travels to the shops 5 miles North from his home, then he travels to the post oﬃce 3 miles West from the shops. Afterwards he travels home. a. What is the total distance Jacob travelled? b. What is the total displacement of Jacob? Example 6 A person walks from position A all the way around and ends up back at position A. What is the person’s distance and displacement? 2.3 Speed and Velocity Speed (Scalar) Velocity (Vector) The distance travelled by an The DISPLACEMENT of an object object during a given time during a time interval DIVIDED by interval DIVIDED by the time the time interval. interval. Velocity is a vector, so it should No direction is needed as it is a include a DIRECTION scalar Calculating Speed PRACTICE: 1. A vehicle travels a distance of 120 km over a period of 1.5 h. Calculate the average speed of the vehicle. 2. A tsunami travels a distance of 4.0 x 106 m over a period of 36000.0 s. Calculate the average speed of the tsunami. 3. Convert the average speed of the tsunami determined in question #2 into km/h. 4. A plane ﬂies at an average speed of 694 m/s. Calculate how long it would take the plane to ﬂy around the world, a distance of approximately 4.00 x 107 m. 5. A train travels at an average speed of 6.9 m/s for a period of 160 s. Calculate distance travelled by the train. Calculating Velocity Example 1 A skier goes 148m [W] in 5.50s. What is the skier's velocity? Example 2 A cheetah runs at a velocity of 29 m/s [N]. If it runs for 8.4s, what is its displacement? Example - Speed vs Velocity Edmonton to Peace River Imagine that your family was driving from Edmonton to Peace River. It is a long trip so you stopped once for a meal and two other times for snacks. The entire trip took 7.5 h. The distance along the highway is 485 km and the displacement is 365 km[N40°W]. Speed vs Velocity Edmonton to Peace River Solve for speed and velocity: 2.4 Uniform Motion Any object that travels in a straight line at a constant speed is said to have uniform motion. What are some examples of uniform motion? Is it common for things to have uniform motion indefinitely? Plotting Speed on a Graph The average speed of an object can be graphed by plotting the distance it travels vs. the time required to travel said distance Note: The slope of the line represents the object’s speed! Practice #1 a. Examine the graph to the left. Which object is moving the fastest? How do you know? b. Calculate the average speed of objects A, B, and C. Practice #2 Describe the motion of the object at each of the following points. A= B= C= D= Graphing Velocity: Displacement-Time Graphs Average velocity can be plotted using a displacement (or position) - time graph. This looks very similar to a speed graph, but now direction can be taken into account. Uniform Motion - Velocity Time Graphs Velocity can also be plotted over time. If velocity remains constant, then there is uniform motion. This graph represents uniform motion. The object maintains the same velocity over the 15 second time period. 2.5 Non-Uniform Motion and Acceleration Acceleration is defined as any change in the velocity of an object during a time interval. This change could be an increase/decrease in the magnitude of the object’s velocity OR a change in the direction of the object Since acceleration is related to changes in velocity and velocity is a vector quantity, this means that acceleration is also a vector. Calculating Acceleration Practice:. A car merges onto the highway travelling at a velocity of 14 m/s [N]. After 5.5

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