Chem Revise PDF

Lesson 1 Lab safety Lab safety rules 1. Never do an experiment without instructions/approval from the teacher. And read all instructions/directions before the start of an experiment. 2. Safety goggles must be worn at all times during experiments. 3. Liquid waste must not be disposed of in the containers provided and not down the sink. 4. Broken glass goes in the broken glass container. 5. Report all accidents to our teacher ASAP. 6. Use only the amount of materials instructed in the instructions. This is because a controlled amount of chemicals can help us reduce the chance of chemical reactions. 7. Never smell or taste chemicals since they may be poisonous. 8. There shouldn’t be horseplay in the lab area as someone could get seriously hurt. 9. Never put out a chemical fire with water since it will spread. We should smother it instead or use a fire extinguisher. 10. Never leave our lab area unattended while a lab is in progress. We should already have all our materials at our workstation before the beginning of the experiment. 11. Clean up all spills and equipment after each lab activity. Our equipment and lab area must be as clean as we found it or cleaner. Lesson 2 Observation and inferences Observation A good question is formed from observations. Observations are formed from using the five senses to gather information such as notes and record facts. 2 type of observations ○ Qualitative Observations which can be made without measurement and can be recorded without the need for numeric values. ○ Quantitative Observations which give data that can be put in terms of a quantity(numeric values) Inference Logical interpretation based upon prior knowledge and experience Based upon observations ⛤ Observation vs inference Observation ○ Based on five sense Sight Smell Touch Taste hearing Inference ○ Based on prior and new knowledge, facts, and opinions. Predictions ○ Guessing what will happen next based on observations. Lesson 3 Particles to solution Particle theory-Explanation of what matter is made of and how it behaves -The particle theory: 1. Matter is made up of tiny particles with space between them. a. Matter=Anything that has a mass and takes up space b. Matter exists in states(Solid, liquid, gas) i. Solids are very compact(Not much space to move around) ii. Liquid have more space but not too much as they still stick together but can move. iii. Gas can move freely in the air bouncing. 2. The particles of a substance move faster as its temperature increases(excited state) a. Increase in temperature happens when we add heat. i. Heat is energy b. When we add energy to particles they move more faster 3. Different substances are made up of different kinds of particles. 4. Particles are in constant random motion. a. The particles in a gas are in continuous, rapid, and random motion. b. The particles travel in straight line paths until collision. The particles then change direction. 5. Particles attract each other. a. Solid objects-High force of attraction b. Liquid objects-Medium force of attraction c. Gas-Low force of attraction Classification of matter Pure substances: Matters that cannot be separated at all by any physical means are PURE. In a pure group there is an element and compound. Elements are only one kind of atom-Such as oxygen and carbon Compounds have 2 or more types of atoms-such as water and salt Mixture substances: Matter that can be separated by physical means is called a mixture. In matter there are two groups, Homogeneous and Heterogeneous. Homogeneous are uniform meaning they become one such as salt water and the atmospheric air. Heterogeneous are clear different objects such as chocolate chip cookies(chocolate chip and cookies) or Pizza(pizza bread, toppings) Lesson 4 Physical and chemical properties Physical properties(Observed by our senses(qualitative) and/or measured by measurement(Quantitative/numbers) Describes the characteristics of a substance that can be observed or measured. ○ For example the the melting point of a substance(degrees/ celsius) Physical properties ○ Colour ○ Lustre(shininess) ○ Optical clarity ○ Brightness ○ Viscosity ○ Hardness ○ Malleability ○ Ductility ○ Electrical conductivity To be more specific ○ Quantitative Property that’s measured and had numeric value Temperature Height Mass ○ Qualitative A property that is not measured and does not have a numerical value Observations made by the 5 senses Colour Odour Taste Texture Sound Physical change A change in which the composition of the substance stays the same. No new substance is formed. Matter changes but no new matter is made. ○ Bending/Breaking/Cutting Material changes form but it isn’t new ○ Change of state Material changes into another state(Water-Ice) ○ Dissolving Sugar in water-sugar still in water Chemical properties(Observed by a chemical reaction with another substance(Describes the ability of a substance to change into a new substance(s)) Flammability ○ How easy something lights on fire Combustibility ○ Rusting-When a metal is exposed to air, it can rust. Chemical change Process where a chemical change occurs. A new substance(s) is formed. ○ Evidence that shows there is a chemical change Light or heat is produced New Odour is created A precipitate forms A formation of a new solid inside a liquid Gas or bubbles are produced An unexpected change in colour Lesson 5 Characteristics of physical properties A physical property that is unique to a substance can be used to identify the substance. Density -We can measure the volume of an object by mass. Density=mass/volume 3 characteristics of physical properties of PURE substances 1. Density a. The ratio of a substance’s mass to its volume Mass b. A measurement of the amount of matter something contains. Weight c. The measurement of the pull of gravity on an object. Volume d. How much space matter occupies e. The amount of space that an object takes up is the object’s volume. f. Standard units are mL and cm^3. Formula for calculating density and manipulating formula Density=Mass/Volume 2. Freezing/Melting point 3. Boiling point Unusual properties of water When lead goes from liquid to solid state it keeps shrinking and occupies less space as it is more dense. Solid water on the other hand takes up more space and is less dense. This causes solid water(ice) to float on liquid water. Water as a solid takes up more space due to the hexagonal structure of the hydrogen bonds. Water groups in 6 to form a hexagon. 1. Freezing point a. Temperature at which a substance turns from a liquid to a solid 2. Melting point a. Temperature at which a solid turns into a liquid. 3. Boiling point a. Temperature at which a substance turns from liquid to gas. Lesson 6 Periodic table of elements Group are vertical(UP AND DOWN) Periods are horizontal(left and right) Period 1’s are special elements Important definitions Elements A pure substance that cannot be broken into a simpler chemical substance by any physical or chemical means. Element symbol An abbreviation for a chemical element. Compound A pure substance composed of two or more different elements What is inside an element’s box What is an atom? The smallest unit of matter What matter is made of Atom is made up of protons, Neutrons and electrons The atomic structure consists of the nucleus in the center and electrons to surround the nucleus via orbiting. Metals vs non-metals Metals Are found on the left side of a periodic table Reveal a metallic sheen when freshly cut. Have metallic properties such as lustre, ductility, malleability. Non-metals Found on the upper right portion of the periodic table. Mostly gasses and dull powdery solids. Metalloids Have properties of both metals and nonmetals. Found at the boundary between metals and nonmetals Lesson 7 Atomic theories What are atoms? Atoms are the smallest form of matter. ○ Matter is anything that takes up space. Everything is made of atoms Atoms are known as the basic building blocks of matter. Theory Scientific theory –An expression of our best understanding of scientific phenomena based on scientific evidence or reasoning. –As technology advances we may need to adjust the theories. Key scientists that aided in the development of the model of the atom. Democritus(400 BC) ○ States: All matter can be divided into smaller and smaller pieces until we reach a single particle. ○ Stated: Atoms are of different sizes, in constant motion, and separated by empty spaces. Aristotle(384-322 BC) ○ Thought that all matter was made up of earth, water, air, and fire. ○ These substances have four specific qualities: dry, wet, cold, and hot. ○ This theory was accepted for almost 2000 years. John Dalton(1807) ○ Proposed that: All matter is made of small indivisible particles called atoms. All atoms of an element are identical Atoms are rearranged to form new substances in chemical reactions, but are never created or destroyed. ○ Dalton’s billiard ball model wasn’t able to explain negative and positive charges. Thomson(1897) ○ Experiment with a cathode ray tube. ○ Manipulated the stream of particles with positively and negatively charged objects Found that: Atoms contain negatively charged electrons. Since atoms were and are neutral, the rest of the atom must be a positively charged sphere. The electrons are distributed evenly throughout the atoms. ○ The cathode ray tube experiment was called the Plum Pudding model. Rutherford(1909) ○ Through his gold foil experiment, Rutherford proposed that: The center(Nucleus) is made up of positively charged particles(protons). The Nucleus makes up most of the mass but takes up little space(mostly empty space). Chadwick(1932) ○ Chadwick discovered a particle that could smash atoms but had no charge(Neutrons). ○ Chadwick proposed that: Nucleus is made up of protons and neutrons. A neutron has the same mass as a proton. Electrons circle rapidly around the nucleus. Neutral atoms have the same amount of electrons and protons. Neils Bohr ○ Passed light made from different gasses through a prism. ○ Light is given off when an electron moves to a lower orbit. ○ Therefore Nelis Bohr proposed that: Electrons orbit the nucleus at different levels(shells, orbits). When an electron gains energy it goes up an orbit and when it loses energy it goes down an orbit. Lesson 8 Periodic table explained Atomic number The number represents the number of protons in the nucleus of the element. Number of protons is equivalent to the number of electrons. Mass Number Mass Number=Number of protons+number of neutrons. Isotopes An atom with the same number of protons but a different number of neutrons. (Atoms with different atomic masses of the same element are isotopes of each other). 1. Lithium as an example a. LI-6 vs Li-7 i. Both isotopes are stable and exist in nature but Li-7 is more common, BUT there are small amounts of naturally occurring Lithium that have 3 protons and 3 neutrons. This is an isotope since Lithium normally has 4 neutrons not 3). Number of neutrons= Atomic mass – Atomic number The most outer layer of the shell is known as the VALENCE SHELL where the electrons on there are called VALENCE ELECTRONS. 1. Group 1 has 1 Valence electron 2. Group 2 has 2 valence electrons 3. Group 13 has 3 valence electrons 4. Group 14 have 4 valence electrons 5. Group 15 has 5 valence electrons 6. Group 16 has 6 valence electrons 7. Group 17 has 7 valence electrons 8. Group 8 has 8 valence electrons. In Shell Number 1 there are a maximum of 2 electrons and in shells 2, 3, and 4 there are 8 maximum electrons. When drawing a Bohr Rutherford diagram the first step is to write it in ↑ → ↓ ← this order. REMEMBER THE FIRST 20 ELEMENTS AND BE ABLE TO DRAW THEM. Lesson 9 Putting atoms together Molecules Two or more atoms of the same or different elements that are chemically joined together in a unit. FOR EXAMPLE: Our air is composed of 80% Nitrogen molecules, 20% oxygen molecules and small amounts of water molecules and carbon dioxide molecules. Molecule types Formed by sharing electrons Molecular elements and Molecular compounds Formed ionic bonds by giving electrons Ionic compounds Chemical bonding rules of electrons and atoms. Number 1. Electrons can move and jump from atom to atom. Metals give electrons to nonmetals. Number 2. Atoms want to have a full outer shell of electrons. Because having a full outer shell makes them more stable. Number 3. Electrons will move or be shared so that atoms will gain a full outer shell. Covalent and Ionic bonds. Covalent Bonds Non-metal+Non-metal ○ Share valence electrons so that they have full valence shells. Molecular elements are a molecule that consists of atoms of the same elements(Diatomic molecules) HOFBrINCI Hydrogen=H=H2 Oxygen=O=O2 Fluorine=F=F2 Bromine=Br=Br2 Iodine=I=I2 Nitrogen=N=N2 Chlorine=CI=CI2 Molecular compounds A molecule that consists of 2 or more different elements which are held by covalent bonds. Ionic Compounds A compound made up of positive and negative ions. Ionic bonds Metal+Non-metal ○ Metal gives its valence electrons to a non-metal so that they both have a full valence shell. Makes the metal positive and the non-metal negative. What are ions? Ions are a particle or element that has a negative or positive charge. We can tell the ions of an elements on the periodic table by looking at the top right corner of an element which tells us if the element has more than one or lesser ionic charges. Why do elements on the left side of the periodic table have plus and elements on the right side have a negative charge? An ion forms when an atom loses or gains one or more electrons. Net charge –If an atom LOSES an electron, it has one or more protons than electrons so it becomes more positive. –If an atom GAINS an electron, it has one more electron than protons, so it becomes more negative. Cations(Cat-IONS) Positively charged for example Na+. Same name as element for example Sodium Ion Anions(An-IONS) Negatively charged for example Br- Add Ide to the stem of the name for example oxygen becomes oxide ion. Lesson 10 How atoms combine THREE CHEMICAL BONDING RULES FOR ELECTRONS AND ATOMS 1. Electrons can move and jump from atom to atom. 2. Atoms want to have a full outer shell of electrons. 3. Electrons will move or be shared so that atoms will gain a full outer shell. Why do atoms combine? Atoms combine for the sole purpose of becoming more stable. Noble gases ○ Column 18(AKA group 8A) are the most stable They have the maximum amount of electron in their outer shell ○ Helium 2( period 1), All other 8(period 2 and 3) or 18 (period 4) Elements with incomplete outside shells combine with other elements to obtain the maximum number of electrons. Atoms can become more stable by gaining, losing, or sharing electrons Three types of combinations 1. Metals and metals a. Creates alloys b. Solid solution c. Not an actual compound 2. Metal and nonmetals a. Create ionic compounds with ionic bonds 3. Nonmetal and nonmetals a. Create molecular compounds b. Elements with covalent bonds. METALS AND METALS An alloy ○ Solid solution ○ Not a compound ○ A mixture of 2 hot liquid metals that solidify. ○ Help soft metal gain strength. metals + non-metals Ionic compounds are made up of oppositely charged ions(and polyatomic ions) Attracted to each other. Metals lose electrons and become CATIONS(positively charged) Non-metals gain Electrons and become ANIONS(Negatively charged) Non-Metals+Non-metals ○ Covalent bonds formed when 2 or more nonmetals share electrons. ○ This sharing of electrons give the atoms the “illusion” that they have a complete outer shell. Sharing electrons When it comes to sharing electrons with one or more elements to form full outer shells. The electron shared counts for both elements outer shell as elements can share multiple electrons.

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