Matter and Chemical Changes Unit B Matter and Chemical Changes

Safety in the Science Class 1.1 Safety in the Science Class

Lab Safety Safety is the highest priority in the classroom Slide 1 of 7 Safety is the highest priority in the classroom Safety procedures must be followed in the lab(they are on the next few slides) When in the lab, follow all rules! Identify dangers and immediately let your teacher know about them J. Hiscock – Science 9

Safety Procedures Slide 2 of 7 Wear safety glasses or goggles near chemicals or open flames Never pour liquids from a position above your head! J. Hiscock – Science 9

Safety Procedures Slide 3 of 7 Position all equipment safely away from the table edge Do not ever bring food or drink into the lab! J. Hiscock – Science 9

Safety Procedures Clean up all spills immediately! Slide 4 of 7 Clean up all spills immediately! Label all containers or glassware! J. Hiscock – Science 9

Safety Procedures Always be careful around an open flame! Slide 5 of 7 J. Hiscock – Science 9

orange diamond “warning” yellow triangle “caution” Safety Hazard Symbols Slide 6 of 7 During experiments, you will see special symbols Safety hazard symbols tell us: type of hazard (p. 94): flammable toxic explosive corrosive degree of the hazard (p. 94): red octagon “danger” orange diamond “warning” yellow triangle “caution” J. Hiscock – Science 9

WHMIS Symbols Last Slide The Workplace Hazardous Materials Information System uses round symbols to indicate hazards The main WHMIS symbols (p. 95) are: compressed gas corrosive flammable and combustible oxidizing material poisonous and infectious material causing immediate and serious toxic effects poisonous and infectious causing other toxic effects dangerously reactive material biohazardous infectious material J. Hiscock – Science 9

1.2 Organizing Matter Read pg. 97-103

Matter All matter has mass and occupies volume Slide 1 of 7 All matter has mass and occupies volume Matter exists in one of three states: solid, liquid or gas Chemistry is the study of two things: properties of matter changes in matter Two types of changes: physical or chemical J. Hiscock – Science 9

Physical Change Slide 2 of 7 Physical change occurs when a substance changes appearance, but keeps the same composition Changes of state are examples of physical change Change from solid to liquid is melting Change from liquid to gas is evaporation (e.g. boiling water) Change from gas to liquid is condensation (e.g. water on a cold window) J. Hiscock – Science 9

Change of State Change from liquid to solid is freezing (e.g. snow) Slide 3 of 7 Change from liquid to solid is freezing (e.g. snow) Change of solid to gas is sublimation (e.g. comet) Change of gas to solid is deposition (e.g. frost) Also acceptable is sublimation as change of gas to solid J. Hiscock – Science 9

Chemical Change Slide 4 of 7 Chemical change occurs a substance reacts to form one or more new substances J. Hiscock – Science 9

Physical Properties Slide 5 of 7 Properties are the characteristics used to describe a substance Physical properties describe the physical appearance and composition of a substance Physical properties: melting point, boiling point, hardness, malleability, ductility, crystal shape, solubility, density and conductivity See green table p. 99 for explanation of these J. Hiscock – Science 9

Chemical Properties Slide 6 of 7 A chemical property describes how a substance interacts with other substances See purple table p. 102 to see examples of chemical properties J. Hiscock – Science 9

Classification Matter Pure Substances Mixtures Elements Compounds Last Slide Matter Pure Substances Mixtures Elements Compounds Mechanical Mixtures Solutions Suspensions Colloids Can see different particles Can not see different particles Cloudy – can separate Cloudy – cannot separate J. Hiscock – Science 9

1.3 Observing Changes in Matter Read pg. 105-109

Changes in Matter Slide 1 of 5 A physical change of matter is usually more obvious than chemical change e.g. paper tearing, ice melting A chemical change results in the formation of new substances e.g. potassium reacting with water J. Hiscock – Science 9

Chemical Change? Change in colour e.g. bleaching of clothes Slide 2 of 5 Change in colour e.g. bleaching of clothes J. Hiscock – Science 9

Chemical Change? change in odour e.g. cow emissions e.g. burning smell Slide 3 of 5 change in odour e.g. cow emissions e.g. burning smell J. Hiscock – Science 9

Chemical Change? release or consumption of energy Slide 4 of 5 formation of gas bubbles or solid precipitate e.g. lead iodide solid release or consumption of energy e.g. potassium in water J. Hiscock – Science 9

Chemical or Physical? Last Slide Sometimes it is not clear if there is a chemical change or a physical one e.g. boiling of liquid vs. formation of bubbles Chemical analysis may be needed to determine which type of change J. Hiscock – Science 9

Evolving Theories of Matter Read pg. 112-120 Evolving Theories of Matter 2.1

The Stone Age Over 10,000 years ago, man was in the Stone Age Slide 1 of 12 Over 10,000 years ago, man was in the Stone Age Metals were discovered only after 8000 B.C. Fire was originally used for cooking and heating Fire was also used to make ceramics Fire eventually was used to melt down metals and metallurgy came to be J. Hiscock – Science 9

The First Chemists Slide 2 of 12 “Chemistry” came from khemeia: Greek for “juice of a plant” Between 6000 and 1000 B.C., early chemists produced valuable metals such gold and copper Gold is valuable because it does not tarnish; it is ductile and malleable Heated copper is stronger and more flexible Hittites started the Iron Age by extracting iron from rocks and melting it into pots and swords J. Hiscock – Science 9

Democritus Slide 3 of 12 Greek philosopher Democritus believed that matter could be broken down into indivisible bits called atomos: “atoms” Democritus believed that different atoms made different materials He also believed that combining different atoms made new materials J. Hiscock – Science 9

Alchemists Slide 4 of 12 The first modern chemists were the alchemists, who tried to make gold out of other metals Not scientists, but they performed the first experiments Common glassware like beakers and filters were invented by alchemists Alchemists invented plaster of Paris, and wrote the first chemistry textbook J. Hiscock – Science 9

Discovery of Metals Gold – 6000 B.C. Copper – 4200 B.C. Slide 5 of 12 Gold – 6000 B.C. Copper – 4200 B.C. Silver – 4000 B.C. Lead – 3500 B.C. Tin – 1750 B.C. Iron – 1500 B.C. Mercury – 750 B.C. J. Hiscock – Science 9

Chemistry as Science Slide 6 of 12 Boyle (~1660) believes the purpose of chemistry is to determine what all materials are made of J. Hiscock – Science 9

Chemistry as Science Slide 7 of 12 Lavoisier (~1780) comes up with a system of naming chemicals: “father of modern chemistry” J. Hiscock – Science 9

Chemistry as Science Slide 8 of 12 Dalton (1808) suggests all matter is made of elements He also suggests that each element is composed of particles called “atoms” Atom is the smallest unit of an element of matter J. Hiscock – Science 9

Chemistry as Science Slide 9 of 12 J.J. Thomson (1897) discovered electrons, negatively charged particles of the atom He presents the “raisin bun” or “plum pudding” model of atom: positive sphere with electrons embedded in it J. Hiscock – Science 9

Chemistry as Science Slide 10 of 12 Nagaoka (1904) proposes “solar system” model: large positive nucleus with electrons orbiting around it Rutherford (1908) offers support for the “solar system” model using his gold foil experiment J. Hiscock – Science 9

Chemistry as Science Slide 11 of 12 Bohr (1922) presents the electron shell model (Nobel Prize) Electron shells are specific circular orbits that electrons follow around atomic nuclei J. Hiscock – Science 9

The Modern Atom Last Slide Chadwick discovers that the nucleus of an atom contains protons and neutrons (after 1922) Nucleus is the positively charge center of an atom, containing protons and neutrons Protons are the positively charged particles in the atomic nucleus Neutrons are the neutrally charged particles in the atomic nucleus Quantum chemistry describes “electron clouds” J. Hiscock – Science 9

Organizing the Elements 2.2 Organizing the Elements Read pg. 122 - 125

Symbols of Elements There were many attempts to classify elements Slide 1 of 4 There were many attempts to classify elements The Greeks used celestial bodies as symbols: Dalton came up with his own system: J. Hiscock – Science 9

A Beginning Slide 2 of 4 By comparing known elements to carbon, their approximate atomic masses could be figured out! Atomic mass is the mass of one atom of an element John Newlands figured out a pattern when elements were compared by atomic mass No one believed him! Until... J. Hiscock – Science 9

Mendeleev Slide 3 of 4 Mendeleev wrote the names and properties of 63 elements on cards He arranged and rearranged the cards Goal #1: find a pattern! Goal #2: predict future elements! J. Hiscock – Science 9

Mendeleev’s Table Behold, the Mendeleevian Periodic Table: Last Slide Behold, the Mendeleevian Periodic Table: Confusing, but it predicted elements correctly! J. Hiscock – Science 9

2.3 The Periodic Table Today Read pg. 126-134

Mendeleev’s Table Today? Slide 1 of 9 J. Hiscock – Science 9

Metals Modern Periodic Table Non-metals Metalloids Metal and Non-metal Slide 2 of 9 Metal and Non-metal Non-metals Metalloids Metals J. Hiscock – Science 9

Modern Periodic Table Atomic Number Ionic Charge Element Symbol Slide 3 of 9 Atomic Number Ionic Charge Element Symbol Element Name Atomic Mass J. Hiscock – Science 9

Names vs. Symbols Slide 4 of 9 The elements have names that come from: Greek, Latin, geographic location, planets, minerals, famous scientists, etc. Modern symbols made of 1-2 letters BUT...Element symbols don’t always relate directly to element names e.g. Sb corresponds to Antimony J. Hiscock – Science 9

Atomic Number vs. Mass Slide 5 of 9 Atomic number - number of protons (p+) in an atom e.g. chlorine (Cl) has 17 protons Atoms are neutral (not charged), so atomic number also equals the number of electrons (e-) Atomic mass = (mass of p+) + (mass of no) J. Hiscock – Science 9

Mass Number Mass number = (# of p+) + (# of no) Slide 6 of 9 Mass number = (# of p+) + (# of no) To calculate the mass number of an element, round the atomic mass to the nearest whole number e.g. bromine (Br) has an atomic mass of 79.90 g/mol, so its mass number = 80 J. Hiscock – Science 9

Number of Neutrons To calculate the number of neutrons in an element: Slide 7 of 9 To calculate the number of neutrons in an element: = (Mass number) – (Atomic number) e.g. neon (Ne): atomic number = 10, & atomic mass = 20.18 mass number = 20 # neutrons = 20 – 10 = 10 no J. Hiscock – Science 9

Summary of subatomic particles p+ = atomic number e- = atomic number no = mass number – atomic number Ex: Identify the number of subatomic particles of lithium: J. Hiscock – Science 9

Periods/Orbits Horizontal rows are called periods or orbits Slide 8 of 9 Horizontal rows are called periods or orbits Moving from left to right increases atomic number and atomic mass There are 7 periods in total J. Hiscock – Science 9

Groups/Families Vertical columns are called groups or families Last Slide Vertical columns are called groups or families Total of 18 families of elements Families of elements usually have similar properties e.g. noble gases in group 18 are generally non-reactive (inert) J. Hiscock – Science 9

3.1 Naming Compounds Read pg. 138-142

Compounds Metals are elements that exist as single atoms Slide 1 of 7 Metals are elements that exist as single atoms e.g. Cu, Hg, Na Non-metals are elements that can exist as single atoms or as molecules Compounds are molecules made of more than one atom bonded together Compounds can be made of different elements or the same element e.g. S8, CO2, P4, MgCl2 J. Hiscock – Science 9

Chemical Formulas Chemical formulas tell us two things: Slide 2 of 7 Chemical formulas tell us two things: What elements are in a compound How many atoms there are of each element We determine these two things by: The chemical symbols present A subscript next to each symbol The subscript tells us how many atoms there are of a given element J. Hiscock – Science 9

Chemical Formulas Slide 3 of 7 Subscript of “2” after “H” means there are 2 atoms of hydrogen. No subscript after “O” means there is 1 atom of oxygen. J. Hiscock – Science 9

Chemical Formulas Slide 4 of 7 Subscript of “2” after “H” tells us there are two atoms of hydrogen. Subscript of “2” after “O” tells us there are two atoms of oxygen. J. Hiscock – Science 9

Physical States Slide 5 of 7 Sometimes a state of matter is written next to the molecule: (s) means a substance is in the solid state (l) means a substance is in the liquid state (g) means a substance is in the gas/vapour state (aq) means a compound is dissolved in water J. Hiscock – Science 9

Ionic Vs. Molecular Compounds are classified in two ways: Ionic Slide 6 out of 7 Compounds are classified in two ways: Ionic Molecular Ionic compounds: the elements that combine are: a metal and a non-metal Molecular compounds: the elements that combine are ALL non-metals J. Hiscock – Science 9

Ionic Vs. Molecular Identify each compound as ionic or molecular: Last Slide Identify each compound as ionic or molecular: NaCl - CO2 - PdF3 - O2 - SO4 - Li3N - RuP - J. Hiscock – Science 9

3.2 Ionic Compounds Read pg. 144-149

Ions Why do compounds form? Elements want to fill their outer electron shell so they take away or give electrons to each other. Ex. F Li J. Hiscock – Science 9

Ions Metals form compounds by donating electrons to non-metals Slide 1 of 9 Metals form compounds by donating electrons to non-metals Transfer of electrons from metal results in: positively (+) charged metal ions negatively (-) charged non-metal ions An ion is the charged form of an atom Ionic charge is called the “combining capacity” of a metal or a non-metal J. Hiscock – Science 9

Ionic Charge Slide 2 of 9 J. Hiscock – Science 9

Ionic Charge Slide 3 of 9 Ionic charge written as superscript in upper right hand corner of a symbol (e.g. Oxygen ion is O2-) Some metals have more than one possible ionic charge (e.g Copper ions could be Cu2+, Cu+) An ionic bond is the attraction between the (+) charge of one ion, and the (-) charge of another ion J. Hiscock – Science 9

Ionic Charge Slide 4 of 9 J. Hiscock – Science 9

Ionic Charge Practice – for each element list the ionic charge(s): Slide 5 of 11 Practice – for each element list the ionic charge(s): - Ag - Pb - Au - Ca - N - F - Fe - W - Cu - V - O - Br - Li - Hg - P - S J. Hiscock – Science 9

Naming Rules sodium sodium chlorine “chlorine” Becomes “chloride” Slide 5 of 9 sodium Ex: NaCl Write the chemical name of the (+) metal ion first. 2) Write the chemical name of the (-) non-metal ion second. 3) Change the ending of the (-) non-metal ion from its ending to “-ide”. sodium chlorine “chlorine” Becomes “chloride” to give sodium chloride J. Hiscock – Science 9

Naming Rules Mg2+ Mg2+Cl- Write the (+) metal ion’s symbol first. Slide 6 of 9 Ex. Magnesium chloride Mg2+ Write the (+) metal ion’s symbol first. 2) Write the (-) non-metal ion’s symbol second. Mg2+Cl- J. Hiscock – Science 9

Naming Rules Mg2+Cl- becomes Mg2+Cl-Cl- Slide 7 of 9 3) Balance the ion charges so that the (+) charge cancels out the (-) charge in the compound. The compound should have overall charge of “0”. Mg2+Cl- becomes Mg2+Cl-Cl- J. Hiscock – Science 9

That’s it! You have written a formula! Naming Rules Slide 8 of 9 Count the number of atoms of each element in the formula. Put the number of atoms of each element in a subscript next to the element. A subscript of “1” is invisible. Remove all (+) and (-) charges. Mg2+Cl-Cl- becomes MgCl2 That’s it! You have written a formula! J. Hiscock – Science 9

Naming Rules Some metals have more than one possible ionic charge. Slide 8 of 9 Some metals have more than one possible ionic charge. SPECIAL NAMING RULE: If the compound contains a metal with more than one possible ionic charge, we write the ionic charge in Roman numerals, beside the metal’s name. Examples: iron (II) oxide iron (III) oxide J. Hiscock – Science 9

Examples CaCl2 Cobalt (I) oxide Aluminum oxide Last Slide J. Hiscock – Science 9

Molecular Compounds 3.3 Read pg. 150-153

Covalent Bonds Slide 1 of 5 A covalent bond is the sharing of electrons between atoms A molecular compound forms when two non-metals join together Ionic compounds have higher melting points and boiling points than molecular compounds Molecular compounds that contain hydrogen have common names (e.g. water, ammonia) J. Hiscock – Science 9

Naming Rules The first element in the compound uses its element name. Slide 2 of 5 The first element in the compound uses its element name. e.g. name for N2O3 starts with nitrogen The second element in the compound uses its element name with an “–ide” ending e.g. name for N2O3 ends with oxide J. Hiscock – Science 9

e.g. name for N2O3 is dinitrogen trioxide Naming Rules Slide 3 of 5 When there is more than one atom for an element in the formula, a prefix is used. e.g. name for N2O3 is dinitrogen trioxide 1 atom mono- 6 atoms hexa- 2 atoms di- 7 atoms hepta- 3 atoms tri- 8 atoms octa- 4 atoms tetra- 9 atoms nona- 5 atoms penta- 10 atoms deca- Prefixes J. Hiscock – Science 9

e.g. name for OCl2 is oxygen dichloride Naming Rules Slide 4 of 5 If the first element has only one atom, there is no prefix for it (BUT...the second element always gets a prefix!) e.g. name for OCl2 is oxygen dichloride J. Hiscock – Science 9

Molecular Formulas Last Slide Using the four big rules, the name of your molecular compound should look like this: Prefix + first element Prefix + second element (-ide) To make a formula from a chemical name: turn the element names into symbols turn the prefixes into subscript numbers e.g. dinitrogen monoxide is N2O J. Hiscock – Science 9

4.1 Chemical Reactions Read pg. 156-161

New Substances Slide 1 of 5 A chemical reaction occurs when two substances react to produce a new substance or substances J. Hiscock – Science 9

Chemical Equations Slide 2 of 5 A chemical equation helps us to understand a chemical reaction: reactant A + reactant B  product A + product B Reactants are substances that are used up Products are substances that are produced during reaction Ex. HCl + NaOH  H2O + NaCl (Reactants) (Products) J. Hiscock – Science 9

Exothermic Reactions Slide 3 of 5 When a chemical reaction releases energy, it is considered to be exothermic Exothermic reactions can emit light, heat, sound, electricity, or even motion In this type of reaction, the products require less energy to form than the reactants do e.g. sodium in water J. Hiscock – Science 9

Endothermic Reactions Slide 4 of 5 When a chemical reaction absorbs energy, it is considered to be endothermic Endothermic reactions may require heat or even electricity In this type of reaction, it takes more energy to form the products than the reactants e.g. recharging a battery J. Hiscock – Science 9

Reactions with Oxygen Last Slide Combustion is when oxygen reacts with a substance to produce a new substance and energy e.g. gasoline + oxygen  carbon dioxide + water Corrosion is a chemical change in which oxygen in the air gradually reacts with a metal e.g. iron + oxygen  iron(III) oxide Cellular respiration is the reaction of organic molecules with oxygen, and occurs only in cells e.g. glucose + oxygen  carbon dioxide + water J. Hiscock – Science 9

IMPORTANT!!! Some elements - when they are ALONE ONLY - like to partner up: Fluorine = F2 Nitrogen = N2 Chlorine = Cl2 Oxygen = O2 Bromine = Br2 Phosphorus = P4 Iodine = I2 Sulfur = S8 Astatine = A2 J. Hiscock – Science 9

IMPORTANT! When writing a chemical formula we also have to include the states: (g) is gas (l) is liquid (s) is solid You can tell the state of elements by looking at the front on the periodic table Write compounds as solid (unless otherwise indicated) Ex: Na(s) + F2(g)  NaF(s) J. Hiscock – Science 9

Examples: Magnesium reacts with oxygen to form magnesium oxide Salt decomposes to form sodium and chlorine J. Hiscock – Science 9

Definitions Write the following for NaCl: Element symbols = Na and Cl Element names = sodium and chlorine Chemical formula = NaCl Chemical name = sodium chloride J. Hiscock – Science 9

Conservation of Mass in Chemical Reactions 4.2 Conservation of Mass in Chemical Reactions Read pg. 163-165

Lavoisier’s Experiment Slide 1 of 5 Lavoisier tried burning sulphur with phosphorous He measured the mass of reactants before reaction He also measured the mass of the products after reaction The mass of the reactants was equal to the products!! J. Hiscock – Science 9

No Mass is Lost! Slide 2 of 5 The products of a chemical reaction usually look different than the reactants Something may “disappear” during a chemical reaction The atoms that went in are still the atoms that came out…they’re just rearranged J. Hiscock – Science 9

Conservation of Mass Slide 3 of 5 Law of Conservation of Mass: the total mass of the products always equals the total mass of the reactants in any chemical reaction!!! In other words: same atoms with a different arrangement! J. Hiscock – Science 9

Open and Closed Systems Slide 4 of 5 In an open system, reactants or products are not contained and may escape out, or interact with the air e.g. rusty car In a closed system, reactants and products are trapped and the reaction can occur without interacting with air e.g. lunar rover J. Hiscock – Science 9

Balanced Equations Last Slide We have to balance atoms going into a reaction with the atom coming out To satisfy conservation of mass, we write a balanced chemical equation: e.g. CH4 + O2  CO2 + H2O becomes CH4 + 2O2  CO2 + 2H2O J. Hiscock – Science 9

4.3 Factors Affecting the Rate of a Chemical Reaction Read pg. 166-169

Reaction Rate Reaction rate is how fast a chemical reaction occurs Slide 1 of 3 Reaction rate is how fast a chemical reaction occurs Four different factors could affect the rate of reaction: Presence of a catalyst Concentration of reactants Temperature of system Surface Area of reactants J. Hiscock – Science 9

Catalysts and Enzymes Slide 2 of 3 Activation energy is the energy barrier that has to be crossed for a reaction to occur A catalyst is any substance that lowers or shrinks the energy barrier for a chemical reaction e.g. NaI catalyzes the decomposition of H2O2 An enzyme is a biological catalyst e.g. enzymes in saliva help digest food J. Hiscock – Science 9

The Other Factors Last Slide A higher concentration of reactants means there are more particles around to bump into each other and react A higher temperature causes reactants to bump into each other and react more often A higher surface area means more reactant particles are exposed, and able to react with other reactant particles J. Hiscock – Science 9