Matter & Chemical Change - Unit A PDF

Matter & Chemical Change Unit A Safety Symbols Two different systems of safety symbols have been developed to warn users of potential hazards HSHS WHMIS What does the acronym stand Household Safety Hazard Workp...

Matter & Chemical Change Unit A Safety Symbols Two different systems of safety symbols have been developed to warn users of potential hazards HSHS WHMIS What does the acronym stand Household Safety Hazard Workplace Hazardous Materials for? Symbols Information System Where is it used? For household products (the In labs & industry (people with average consumer) some understanding of chemistry) Number of symbols 3 10 Colour coded? Yes, three shapes and colours No, all symbols are in diamonds are used to indicate degree of and are printed in red, except hazard one HSHS: Household Safety Hazard Symbols Each hazard symbol displays the degree of hazard by the shape and color of the border CAUTION WARNING DANGER Yellow inverted triangle Orange diamond Red octagon LOWEST HAZARD HIGHEST HAZARD The symbol inside describes the type of hazard. Example – A skull (poison) inside a red octagon requires only 1g of poison to kill a 200lb man. A skull in an orange diamond requires 5g to kill the same man. A skull in a yellow triangle requires 30g. WHMIS: Workplace Hazardous Materials Information System Note: WHMIS was recently updated, so your textbook is NOT current. WHMIS - purpose To ensure that all work places across Canada that work with hazardous chemicals have a standardized way for handling and labeling toxic chemicals. Provides: ○ hazard identification ○ product classification ways of safely storing and organizing chemicals ○ labeling methods & material safety data sheets ○ standardized worker training and education  MSDS: Material Safety Data Sheets MSDS sheets are provided by the manufacturer & identify the chemical & physical hazards associated with each substance including: melting boiling points toxicity health effects first aid spill and clean up procedures.  The Scientific Method Models are supported by the scientific method which test hypotheses by making predictions about the outcome of an experiment is performed. The results then provide support or VERY refutation of the hypothesis. SIMPLIFIED! https://www.youtube.com/watch?v=i8wi0QnYN6s  Types of Knowledge Empirical knowledge: observable knowledge (operational) Theoretical knowledge: explains or describes scientific observations, not observable (conceptual) We use interpretation as an indirect form Ice Island? of knowledge that builds on a concept to further describe or explain an observation. Classifying Knowledge Qualitative observation: ○ describes QUALITIES of matter or changes in matter ○ changes in color, state, odor Example: Mg (magnesium) is an odorless, silver-gray solid that burns with bright white light. Classifying Knowledge Quantitative observations: ○ Involves a QUANTITY of matter that can be measured ○ Mass ○ Volume ○ Number of moles Example A 5 cm strip of Mg ribbon burned for 3 s leaving 2 mm of ribbon in the tongs.  Quantitative VS. Qualitative https://www.youtube.com/watch?v=-S2EiPD4-W0  CHEMISTRY The study of substances, their structures, their properties, and the changes that can occur to them Physical properties Describe the physical appearance and composition of a substance. Property Description boiling point temperature of boiling (or condensing) melting point temperature of melting (or freezing) malleability can be flattened into sheets without crumbling ductility can be stretched into wires without breaking colour colour (or colourless) state solid, liquid, or gas at room temperature solubility ability to dissolve (usually in water) crystal formation formation of crystals, appearance of crystals conductivity ability to conduct heat or electricity magnetism magnetic attraction between objects Physical Change A change in size, shape, or state. It still retains all other physical properties. Ex. Melting ice  Chemical Properties Describe the reactivity of a substance. Property Description ability to burn combustion (causing flame, heat and light) flash point temperature needed to ignite a flame behaviour in air tendency to break down, react, 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 red and blue blue 🡪 red - acid litmus red 🡪 blue - base no colour change - neutral Chemical Change A change from one substance to another substance. Ca O S2 Ca S O2 NOTE: in both physical and chemical changes there is Conservation of Mass.  MATTER = Anything that has mass and occupies space. A chemist is most interested in the structure and properties of matter and the changes that occur in matter. EXAMPLES: 1. Digestion – biochemistry 2. Oil or Gas 🡪 plastics – petrochemical engineering 3. Corrosion – chemical engineer 4. Pollution - environmental biologistmatter Classification of Matter Pure Substances All particles of the same substance are the same (all particles have the same chemical and physical properties) 2 types of Pure substance ○ Element – all of these are found on the periodic table. (e.g., sulfur) ○ Compound – 2 or more chemically combined elements (e.g.,. NaCl, H2O) **Note the 2 different types of chemical bonding. Mixtures Combination of pure substances (not chemically combined) 4 types 1. Solutions – homogenous mixture (same parts) Looks similar throughout Soft drinks (sugar is dissolved) 2. Mechanical Mixture – (heterogeneous) ○ You can see all parts clearly ○ E.g.. soil *Note the different parts 3. Suspension – (heterogeneous) ○ The parts are in different states ○ E.g., Mud – soil (solid) & water (liquid) 4. Colloid -(heterogeneous) ○ Similar to suspension but not easy to separate. ○ Colloids look a lot like solutions. If you filter both (solution and colloid) a solution will pass through but a colloid will leave behind chunks if one of the phases was a solid. E.g., Milk, paint, ink…  OBSERVING CHANGES IN MATTER Physical Changes When a substance changes from one state to another Physical changes are reversible Chemical Changes Chemical changes occur when two or more substances react and form a new substance The new substances have different properties than the original substances CHEMICAL REACTIONS - There are two parts to a chemical reaction; 1. Reactants (Left side) – the materials present at the start of a reaction 2. Products (Right side) – the new materials produced by the reaction Direction of Reaction EVIDENCE OF REACTION - When chemical reactions occur, a new substance forms and evidence of the reaction may include one or more of the following: - A colour change - The formation of an odour - The formation of a solid or a gas (bubbles) - The release or absorption of heat  Food Chemistry Various physical & chemical techniques have been used to enhance and preserve our food. The most common way food goes bad (spoils) is when bad bacteria occur in too large a number. METHODS FOR PRESERVING FOOD Heating and Freezing Heating (cooking)- temporarily sterilizes food (kills the bacteria) Freezing (storage) – halts the growth of bacteria Salting (beef jerky) Salt removes water, by osmosis, from the food and the bacteria in it. This changes the taste of the food but kills the bacteria. METHODS FOR PRESERVING FOOD Fermentation – This process uses beneficial bacteria (lactobacilli) to create a natural preservative (lactic acid). Sauerkraut was made because it lasted long and had vitamin C to fight off Scurvy. Alcoholic beverages are also made this way. METHODS FOR PRESERVING FOOD Smoking – smoking your meat or fish introduces antioxidants that help control the number of bacteria.  Chemistry Through the Ages Metallurgy → science of producing and using metals ○ Gold ○ Copper ○ Bronze ○ Iron Knew the HOW but not the WHY or WHAT Aristotle → attempted to answer “What is matter?” Alchemy → turning cheap metals into gold ○ Experimenting with matter ○ Led to discovery of mercury, acids, improved lab equipment  Model of the Atom Key Features Why the model was rejected/ modified Dalton’s Billiard Ball Model Thomson’s Plum Pudding Model Rutherford’s Saturn Model  Model of the Atom Key Features Why the model was rejected/ modified Bohr Model Current Model: Quantum Mechanical Model RECAP: Model of an Atom https://www.youtube.com/watch?v=xazQRcSCRaY TedEd: The 2,400-year search for the atom Timeline Assignment: due Friday (midnight) via Google Classroom. You should be able to complete up to p. 6 of your workbook.  The Periodic Table https://www.youtube.com/watch?v=rz4Dd1I_fX0 ORGANIZATION Elements are arranged by increasing atomic number. ATOMIC NUMBER = NUMBER of PROTONS! EXAMPLE: C = 6 protons U = 92 protons The Elements There are about 90 naturally occurring elements, and another 25 synthetic elements. Based on their properties… elements can be divided into 3 classes Metals Non- Metals Metalloids Elements are arranged based on similar properties. LEFT and RIGHT of the “staircase line”. LEFT of the line have properties of METALS. RIGHT of the line have properties of NONMETALS. (Normally opposite of metals!) Along the staircase line are METALLOIDS Organization The periodic table is organized into rows and columns. Each horizontal line (or row) is called a period. Represents electron arrangement. Organization Each vertical column forms a group (or family) of elements numbered 1 to 18. The chemical families are groups of elements that have similar chemical and physical properties. Arrangement Organized by atomic number (# of protons) and chemical properties These have similar physical and chemical properties. You must know the following 4: Alkali metals (group 1) Halogens (group 17) second –soft, shiny & reactive (vigorous last with water). –Reactive non- metals –Have one extra electron –Missing one electron (valence electron) Noble Gases (group 18) last Alkaline-earth Metals (group 2) –Non reactive –Shiny and reactive but not soft –Full outer shell or energy –Have 2 extra electrons level The 4 Groups you need to know: GROUP 1 – ALKALI METALS They are soft, shiny and silver in colour They are the most reactive elements Francium is the most reactive metal https://www.youtube.com/watch?v=jx0eQbBDeG8 GROUP 2 – ALKALINE EARTH METALS Shiny and silver in colour, but not soft Second most reactive group Called “Alkaline" earth metals because they form "alkaline“ (Basic, OH-) solutions when they react with water, GROUP 17 – HALOGENS These elements are poisonous and react readily Colored non-metallic elements, colour gets deeper as you move down the group Fluorine is the most reactive non-metal GROUP 18 – (INERT) NOBEL GASES These elements are very unreactive Periodic Table Colouring activity Textbook pages are incorrect, the correct pages are: 30-31 Atomic Theory An atom is the smallest part of an element that still has the properties of that element. A Closer Look at your Table: Proton/Neutron/Electron Numbers The Atom has the same # of protons and electrons. Atomic Number = number of protons and electrons. Number of Neutrons = Atomic Mass – Atomic number  Mass number is protons + neutrons. (n = m.n. – p) Differs from Atomic Mass by a miniscule amount. Number of protons and distribution of electrons give atoms their distinctive chemical and physical properties Particle Symbol Charge Mass Location Proton p+ 1+ 1.7x10-24g Nucleus (atomic number) Neutron n0 0 1.7x10-24g Nucleus Electron e- 1- 9.1x10-28g Surrounding nucleus (in orbitals or energy levels)  Energy Levels of Electrons Valence electrons – the electrons in the outermost energy level Orbits or Energy * Maximum number of Levels electrons held by each Energy levels energy level can be empty, partly filled or completely filled! Bohr Diagrams Bohr Diagrams Bohr Diagrams Bohr Diagrams Bohr Diagrams Bohr Diagrams Bohr Diagrams - Try Yourself https://www.youtube.com/watch?v=wy83UlGQpWw Noble Gases Noble gases have full energy levels… these atoms are happy and stable! What about all the other elements? Other elements however, do not, so they will form IONS (charged particles). Valence Electrons ATOM IONS -e in outer energy level Cation = + charge Anion = - charge  Formation of Ions Recall: An atom of any element is neutral, so the number of protons equals the number of electrons. An ion is a an atom (or a group of atoms) that has a positive or negative electric charge. The formation of an ion is called ionization, and is the result of an atom either gaining or losing electrons. Cations are positively charged ions. - They are formed when a metal atom loses valence electrons (electrons in the outermost energy level). - As a result, the ion has MORE protons than electrons Anions are negatively charged ions. - They are formed when a non-metal atom accepts electrons into its outer energy level. - As a result, the ion has MORE electrons than protons.  Example: Fluorine The fluorine atom is neutral but unstable. Its outer energy level is now full and, therefore, The fluorine atom will is stable. gain an electron. Although stable, the Fluorine atom is charged (it has gained one extra electron) and is referred to as an Ion.  * Remember the Example: Oxygen electron numbers for each energy level (2,8,8,18)  * Remember the Example: Lithium electron numbers for each energy level (2,8,8,18) Example: Calcium Review: Ionization The number of p never changes but, … in a reaction, an atom will become more (+) or more (-) depending on whether it gains or loses e-’s. ATOMS ARE NEUTRAL! …but unstable IONS ARE CHARGED!! … but stable The Octet Rule - The octet rule says that atoms bond in such a way as to have eight electrons in their valence energy levels. - Atoms tend to be stable with full outer energy levels. https://www.youtube.com/watch?v=4OKy782ePKM - Atoms gain or lose electrons so that they have the same number of electrons as the nearest noble gas. - This explains why some atoms will react with each other and form compounds and others will not. Example: Li = 1 valence e- F=7 valence e- Mg = 2 valence e- IONS are the solution! Metals and non-metals can find a mutual solution to their electrons problem! Multivalent Elements Some metal atoms, form stable ions with more than one charge. Example: copper atoms will lose EITHER one or two electrons. These elements are called multivalent, and the first charge given on the periodic table is the most common. The Atomic Mass Unit Mass of atom too small to use a unit like grams (g). Instead, we use atomic mass unit (amu). An atom of carbon-12 was assigned an exact mass of 12.00 amu. The Atomic Mass Unit Then the relative masses of all other atoms is determined by comparing each to the mass of an atom of carbon-12. Example: an atom twice as heavy has a mass of 24.00 amu = twice as heavey ~ Mg 6.00 amu = half as heavey ~ Li NITROGEN has: – 7 protons – 7 neutrons therefore its mass number is equal to 14 amu … but the atomic mass on the periodic table is 14.01 amu. WHY? Isotopes: –elements that have the same atomic number but a different mass number!  Isotopes Isotopes are different types of atoms of the same element. Can’t change # protons as that changes the element Can’t change the # of e- as that turns it into an ion Only thing left is the # of neutrons. Isotope and Element difference = weight Atomic mass = protons + neutrons BUT … the number of neutrons does not have to be constant. # of Neutrons for any given atom can vary! EXAMPLE: “H” can have 1, 2, or 3 neutrons. “F” can have 9, 10, or 11 neutrons Uses for isotopes The isotopes of hydrogen deuterium (2 neutrons) and (tritium = 3 neutrons) is used for nuclear power generation and nuclear weapons production https://www.youtube.com/watch?v=h7vyKDcSTaE&t=221s Isotope Notation  Example: There are 3 naturally occurring isotopes of carbon: ***The bottom number is sometimes not written because you can determine the atomic number from the symbol. Atomic mass of an element on the periodic table is called the atomic molar mass. Value is calculated as the average mass of all of the isotopes of an element, taking the percent abundance into account. Example: Isotopes of hydrogen: Review: Isotopes Isotopes are atoms from the same element that contain different numbers of neutrons. Ex. This means that Bromine usually has 45 neutrons , however it can sometimes exist as an isotope with 44 neutrons The atomic symbol is sometimes shown with the mass number and the atomic number. Using this format, the isotopes for bromine are: Build An Atom - Simulator https://phet.colorado.edu/sims/html/build-an-atom/latest/build-an-atom_en.html Use this simulator to explore the relationships between atoms, ions, isotopes and the various subatomic particles (protons, neutrons, electrons) for different elements. Review Bohr models and how to use them to represent atoms, ions, and isotopes. Challenge yourself to play the “games”. Good way to check your own knowledge! WORKBOOK PROGRESS This is the end of Part 1. You should be able to complete your first Chemistry workbook.