Unit B Matter and Chemical Change PowerPoint (PDF)

Science 9 Chemistry Concept Map  BELL RINGER #1 1. What are the properties of materials? 2. What happens to materials during chemical change? 3. What evidence do we have of chemical change? 4. What ideas, theories or models help us explain evidence of chemical change? General Outcom...

Science 9 Chemistry Concept Map  BELL RINGER #1 1. What are the properties of materials? 2. What happens to materials during chemical change? 3. What evidence do we have of chemical change? 4. What ideas, theories or models help us explain evidence of chemical change? General Outcome 1 Students will investigate materials, and describe them in terms of their physical and chemical properties Specific Outcomes ⦿ investigate and describe properties of materials ⦿ describe and apply different ways of classifying materials based on their composition and properties, including: − distinguishing between pure substances, solutions and mechanical mixtures − distinguishing between metals and nonmetals − identifying and applying other methods of classification ⦿ identify conditions under which properties of a material are changed, and critically evaluate if a new substance has been produced  1.1 – SAFETY IN THE SCIENCE CLASS Figure 1.1 – pg 93 – What’s wrong with this picture? Title a new lined sheet of paper “30 Reasons Why The Teacher Should Be Fired”. Work with a partner for 15 minutes. ⦿ Safety Rap SAFETY HAZARD SYMBOLS ⦿ All hazardous materials have a label showing a hazard symbol ⦿ The color and shape of the symbol indicates how hazardous a substance is ⦿ The picture inside the shape indicates the type of hazard Hazardous Household Product Symbols  WHMIS SYMBOLS ⦿ Workplace Hazardous Materials Information System ⦿ Another system of easy-to-see warning symbols on hazardous materials ⦿ These symbols were designed to help protect people who use materials that might be harmful at work ACTIVITY: ⦿ WHMIS Kahoot ⦿ Complete the WHMIS foldable and glue into your Journal ⦿ Lab Safety Assignment  NEED EXTRA HELP? MAKE SYMBOL FLASHCARDS ⦿ If you need help learning the WHMIS symbols: ⚫ Create 18 flashcards – include 3 symbol shapes, 7 safety hazard symbols and 8 WHMIS symbols (refer to pg 94 – 95) ⚫ You will need the handout and the rectangles cut into 18 pieces ⚫ On one side, draw and color the symbol. On the other side, name the symbol AND name a product that would have this symbol on it (Hint – you may want to check your cleaning supplies at home) ⦿ Please read Sec 1.1 in your text starting on page 92-96! Achievement Test Prep Achievement Test Prep  1.2 – ORGANIZING MATTER ⦿ Matter exists in three states: solid, liquid, or gas ⦿ Matter can undergo a change in state when energy is used or released ⚫ Red arrows = use energy ⚫ Blue arrows = release energy  PROPERTIES ⦿ Properties are characteristics that can be used to describe a substance Physical Chemical Color Reaction with Acids Lustre (shininess) Ability to Burn Melting Point (solid -> liquid) Reaction with Water Boiling Point (liquid -> gas) Behavior in Air Hardness (resist being scratched) Reaction to Heat Malleability (metal rolled into sheets) Ductility (solid stretched into wire) Crystal Shape (salt is cube shaped) Solubility (ability to dissolve) Density (mass in a given volume) Conductivity (conduct electricity/heat)  PHYSICAL PROPERTIES ⦿ Describe how a substance looks ⚫ color, lustre, melting point, boiling point, hardness, malleability, ductility, crystal shape, solubility, density and conductivity  ACHIEVEMENT TEST PREP Which of the following statements describes the conductivity of elements 3 and 4? A. Both elements are good insulators. B. Both elements are good conductors. C. Element 3 is a good conductor and element 4 is a good insulator. D. Element 3 is a good insulator and element 4 is a good conductor.  PHYSICAL CHANGE ⦿ When a substance undergoes a physical change (like melting), its appearance or state may be altered, but its composition stays the same ⦿ Chocolate Ice Cream:  CHEMICAL PROPERTIES ⦿ Describe how a substance interacts with other substances ⚫ reaction with acids, ability to burn, reaction with water, behaviour in air and reaction to heat ⦿ Only observable when the chemical change occurs  CHEMICAL CHANGE ⦿ A chemical change always results in the formation of a different substance, which has its own unique (different) physical properties (precipitate) ⦿ Chemical Changes Cannot be reversed Optional Videos: Video (8:58 –What are Chemical Properties?) Video (5:42 – Physical Properties and Chemical Properties) ACHIEVEMENT TEST PREP ACHIEVEMENT TEST PREP ACHIEVEMENT TEST PREP Which of the following events is an example of a chemical change? A. Liquid nitrogen evaporates. B. A candle burns. C. Water boils. D. Ice melts. PURE SUBSTANCE OR MIXTURE?  PURE SUBSTANCES ⦿ Pure substances are made up of only one kind of matter and have their own unique set of physical properties ⚫ Element: material that cannot be broken down into any simpler substance (hydrogen, oxygen, carbon) ⚫ Compound: when two or more elements combine chemically (H2O, CO2)  MIXTURES ⦿ Mixtures are a combination of pure substances that DO NOT combine chemically ⚫ Mechanical Mixture (heterogeneous): different substances that make up the mixture are visible (soil, frozen mixed vegetables) ⚫ Solution (homogeneous): different substances that make up the mixture are not visible; one substance is dissolved in another (sugar in coffee, acetic acid in water)  MIXTURES ⦿ Mixtures are a combination of pure substances that DO NOT combine chemically ⚫ Suspension: cloudy mixture in which tiny particles of one substance are held within another; particles can be separated out when poured through filter paper (tomato juice) ⚫ Colloid: cloudy mixture, but particles cannot be easily separated out (milk, ketchup) ACHIEVEMENT TEST PREP Which of the following substances is a solution? A. Acid rain B. Table salt C. Helium gas D. Baking soda PHYSICAL & CHEMICAL CHANGE Virtual Lab ⦿ http://www.learnalberta.ca/content/secsu/html/ matter_and_chemical_change/ChemicalAndPh ysicalChange/index.html 1.3 – OBSERVING CHANGES IN MATTER ⦿ Matter can change from one form to another, or create new materials ⦿ A physical change occurs when a material changes state ⦿ A chemical change occurs when two or more substances react and create a new substance EVIDENCE OF CHEMICAL CHANGE Change in Change in Color Odor Formation Release or of a Solid Absorption (precipitate) of Heat or Gas CONTROLLING CHANGES IN MATTER TO MEET HUMAN NEEDS ⦿ Freeze-drying allows food to be processed by removing the water (by freezing and sublimation) and then packaged to be ready to eat just by adding hot water ⦿ Biologists, to study plant cells and tissue, also use the freeze-drying method ⦿ It has also benefited scientists who need to restore ancient relics or documents that have been damaged by water  FROM CORN TO NAIL POLISH REMOVER AND PLASTIC WRAP ⦿ Scientists are able to change other common materials into useful products ⦿ Corn - makes soda pop bottles, removes paint or nail polish and fuels some cars ⦿ These refined products are more environmentally friendly Bell Ringer #3 ⦿ What are three signs a chemical reaction has occurred? ⦿ What is the MAIN difference between a physical change and a chemical change? ⦿ What is a precipitate? Bell Ringer #4 General Outcome 3 Students will describe ideas used in interpreting the chemical nature of matter, both in the past and present, and identify example evidence that has contributed to the development of these ideas Specific Outcomes ⦿ demonstrate understanding of the origins of the periodic table, and relate patterns in the physical and chemical properties of elements to their positions in the periodic table—focusing on the first 18 elements ⦿ distinguish between observation and theory, and provide examples of how models and theoretical ideas are used in explaining observations ⦿ use the periodic table to identify the number of protons, electrons and other information about each atom; and describe, in general terms, the relationship between the structure of atoms in each group and the properties of elements in that group  2.1 - 2.2 Own Notes Assignment You will read pages 112 - 125 and create notes for these topics. Options: - Doodle Notes - Fill in Jigsaw Notes  2.3 – THE PERIODIC TABLE TODAY ⦿ Dmitri Mendeleev’s periodic table included the 63 known elements of his time ⦿ Elements are listed in order of their atomic mass ⦿ Since then, many more elements have been discovered. Today, about 112 elements are known ⦿ The Elements Song – PLAY THIS  MENDELEEV’S PREDICTIONS: ⦿ Ga – gallium – discovered in 1875 – matched almost exactly his prediction of the properties of an element that would fit that position ⦿ Fr – francium – discovered in 1939 by Marguerite Perey – also matched his predictions exactly  UNDERSTANDING THE PERIODIC TABLE ⦿ Made up of boxes of rows and columns ⦿ Each horizontal row is called a period (#1 – 7) ⦿ Each vertical column forms a group or family (#1 – 18) – elements in the same family have similar chemical properties ⦿ Each box in the periodic table contains several pieces of useful information USEFUL INFORMATION ⦿ Element Symbol and Name ⚫ The large letter(s) in each box show the symbol for the element (ie: O, oxygen) ⚫ Some symbols may be different than the modern name of the element ⚫ The Latin name is used to derive the symbol (ie: modern name – silver, symbol – Ag, Latin name – argentums) USEFUL INFORMATION ⦿ Other names for Elements ⚫ Not all elements are named for Latin words ⚫ Some elements are named after the location in which they were first discovered (ie: californium) ⚫ Other elements are named after scientists who made important contributions to their field of study (ie: einsteinium) USEFUL INFORMATION ⦿ Atomic Number ⚫ The number above the element’s symbol on the left is the atomic number = how many protons are in the nucleus of one atom of that element ⚫ Oxygen atom’s atomic number is 8, therefore it has 8 protons ⚫ Because atoms are neutral, the number of protons equals the number of electrons, so the atomic number also tells you how many electrons are in an atom of a particular element. USEFUL INFORMATION ⦿ Atomic Mass ⚫ The number below the element’s name is the atomic mass ⚫ The atomic mass tells you the total mass of all the protons and neutrons in an atom (electrons are so tiny that they have little effect on the total mass of an atom) ⚫ Atomic Mass is measured by atomic mass unit (amu) ⚫ The atomic mass of oxygen is 16.0 USEFUL INFORMATION ⦿ Calculating Neutrons ⚫ Atomic Mass – Atomic Number = Neutrons ⚫ For example: ○ Oxygen atomic mass = 16.0 ○ Oxygen atomic number = 8 ○ # of neutrons = 16.0 – 8 = 8 ○ # of protons = 8 ○ # of electrons = 8 ⦿ Using the Periodic Table – pg 129  KEY Element Element Name Atomic Atomic # of p+ # of e- # of n0 Symbol Mass Number V Vanadium 50.94 23 23 23 51-23= 28 Ni Nickel 58.69 28 28 28 59-28=31 P Phosphorous 30.97 15 15 15 31-15=16 Br Bromine 79.90 35 35 35 80-35=45 Be Beryllium 9.01 4 4 4 9-4=5 Ar Argon 39.95 18 18 18 40-18=22 Mg Magnesium 24.31 12 12 12 24-12=12 U Uranium 238.03 92 92 92 238-92=146 Si Silicon 28.09 14 14 14 28-14=14 Cr Chromium 52.00 24 24 24 52-24=28 Cl Chlorine 35.45 17 17 17 35-17=18 Ca Calcium 40.08 20 20 20 40-20=20 Ti Titanium 47.87 22 22 22 48-22=26 Valence Electrons ⦿ Valence electrons – The number of electrons in the outer energy level Drawing Bohr Models Hand out Bohr Model Diagram worksheet PATTERNS OF INFORMATION ⦿ By noticing where elements appear in the periodic table, you can tell something about their general nature (refer to pg 126 – 127) ⦿ Metals are shiny, malleable, ductile and conduct electricity - green ⦿ Non-metals are solid, liquid or gas, dull, brittle, don’t conduct electricity (aka insulators) – orange ⦿ Metalloids have both metallic and non-metallic properties - purple  PATTERNS OF INFORMATION ⦿ Groups ⚫ The 18 columns contain groups or families of elements with similar chemical properties ⚫ The exception – Group 1 is divided into two parts – hydrogen and the alkali metals  PATTERNS OF INFORMATION ⦿ Periods ⚫ The rows in the periodic table, called periods, are numbered 1 to 7 ⚫ The elements within the periods gradually change from metal to non-metal ⚫ The most reactive metals are on the left ⚫ As you move right, the metals generally become less reactive The periodic table is organized into rows and columns. Each horizontal line (or row) is called a period. Represents electron arrangement. 1 2 3 4 5 6 7 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. 1 18 GROUP 1 – ALKALI METALS Sodium - They are soft, shiny and silver in colour - They are the most reactive elements - Francium is the most reactive metal Fr  Magnesium GROUP 2 – ALKALINE EARTH METALS - They are shiny and silver in colour, but not soft - They are the second most reactive group - Called “Alkaline" earth metals because they form "alkaline" solutions (OH) when they react with water, so they have a pH greater than seven and are basic.  Fluorine 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 F GROUP 18 – (INERT) NOBEL GASES - These elements are very unreactive The Staircase separates the metals from the non-metals NON-METALS METALS  Summary of PATTERNS OF INFORMATION ⦿ Other Interesting Patterns ⚫ Group 1 elements (except hydrogen) are called alkali metals – these are the most reactive metals (react when exposed to water and air) ⚫ Group 2 elements are called alkaline-earth metals – these are not as reactive as the alkali metals (react when exposed to water and air) PATTERNS OF INFORMATION ⚫ Group 17 elements are called halogens – these are the most reactive non-metals ⚫ Group 18 elements are called noble gases – these are the most stable and unreactive elements ⚫ www.chemicool.com Colour Periodic Table Activity  ACHIEVEMENT TEST PREP Which of the following statements about helium, neon, and argon is true? A. They have the same number of protons. B. They have the same number of neutrons. C. They are solids at a temperature of 25 °C. D. They react with other substances in a similar way. General Outcome 3 Students will describe ideas used in interpreting the chemical nature of matter, both in the past and present, and identify example evidence that has contributed to the development of these ideas Specific Outcomes ⦿ distinguish between ionic and molecular compounds, and describe the properties of some common examples of each General Outcome 4 Students will apply simplified chemical nomenclature in describing elements, compounds and chemical reactions Specific Outcomes ⦿ read and interpret chemical formulas for compounds of two elements, and give the IUPAC (International Union of Pure and Applied Chemistry) name and common name of these compounds ⦿ identify examples of combining ratios/number of atoms per molecule found in some common materials, and use information on ion charges to predict combining ratios in ionic compounds of two elements ⦿ assemble or draw simple models of molecular and ionic compounds Bell Ringer #5 State the number of protons, neutrons and electrons in the following atoms: ⦿ 1) C ⦿ 2) Mg ⦿ 3) P 3.1 – NAMING COMPOUNDS ⦿ Each element has a chemical name ⦿ The combination of elements to form compounds has a chemical name and a chemical formula ⦿ The chemical formula identifies which elements and how many of each are in the compound Aluminum Oxide Al2O3 2 Aluminum; 3 Oxygen  COMBINING ELEMENTS TO MAKE COMPOUNDS ⦿ Ie: ethanol (C2H5OH) has 2 carbon atoms, 6 hydrogen atoms and 1 oxygen atom  COMBINING ELEMENTS TO MAKE COMPOUNDS ⦿ Table salt ⚫ Chemical name: sodium chloride ⚫ Chemical formula: NaCl ⚫ Elements: 1 sodium atom, 1 chlorine atom ⦿ Baking Soda ⚫ Chemical name: sodium bicarbonate ⚫ Chemical formula: NaHCO3 ⚫ Elements: 1 sodium atom, 1 hydrogen atom, 1 carbon atom, 3 oxygen atoms  COMBINING ELEMENTS TO MAKE COMPOUNDS ⦿ Glucose ⚫ Chemical name: glucose ⚫ Chemical formula: C6H12O6 ⚫ Elements: 6 carbon atoms, 12 hydrogen atoms, 6 oxygen atoms NAMING CHEMICAL COMPOUNDS ⦿ A standardized chemical naming system, or nomenclature, is used ⦿ The IUPAC (International Union of Pure and Applied Chemistry) is responsible for determining the appropriate name for each compound ⦿ The metal name is always first  INTERPRETING CHEMICAL NAMES AND FORMULAS FROM COMPOUNDS ⦿ If you know the formula for a compound you can determine its chemical name – if you know its name, you can determine its formula ⦿ Write the chemical formula as determined by the name of the compound. (If a poly atomic ion is part of the formula, keep the poly-atomic ion intact)  INTERPRETING CHEMICAL NAMES AND FORMULAS FROM COMPOUNDS ⦿ Aluminum oxide ⚫ 2 - Al ⚫ 3-O ⚫ Al2O3 ⦿ Calcium nitrite ⚫ 1 - Ca ⚫ 2 - NO2 Polyatomic Ion ⚫ Ca(NO2)2 ⦿ Sodium Chloride ⚫ 1 - Na ⚫ 1 – Cl ⚫ NaCl  INTERPRETING CHEMICAL NAMES AND FORMULAS FROM COMPOUNDS ⦿ If the compound contains a metal, it is ionic ⦿ If the compound does not contain a metal, it is molecular  INDICATING THE PHYSICAL STATE OF A COMPOUND ⦿ Another common notation added to chemical compounds indicates the state of the chemical at room temperature ⚫ NaCl(s) = solid ⚫ H2O(l) = liquid ⚫ CH4(g) = gas ⦿ For substances dissolved in water ⚫ NaCl(aq) = aqueous solutions ACHIEVEMENT TEST PREP Which of the following rows identifies both the elements and number of atoms that are present in one molecule of C6H12O6?  3.2 – IONIC COMPOUNDS ⦿ Sodium Chloride (table salt) – NaCl – is an ionic compound ⦿ Ionic compounds are pure substances formed as a result of the attraction between particles of opposite charges, called ions. ⦿ Formation of NaCl  IONIC COMPOUNDS ⦿ When the ionic compound is dissolved in water, the metal (Na) and non-metal (Cl2) form an aqueous solution of ions ⦿ An ion is an atom or group of atoms that has become electrically charged through a loss or gain of electrons  IONIC COMPOUNDS ⦿ A superscript (+) or a (–) are used to indicate the charge - Na+ and Cl- ⦿ Some ions can also form when certain atoms of elements combine: called polyatomic ions (poly meaning “many”) ⦿ Polyatomic ions are a group of atoms acting as one ⚫ Carbonate = CO32- ⚫ Sulfate = SO42- PROPERTIES OF IONIC COMPOUNDS High Melting Point Good Electrical Conductivity Distinctive Crystal Shape Solid at Room Temperature NAMING IONIC COMPOUNDS ⦿ 1. The chemical name of the metal or positive ion goes first, followed by the name of the non-metal or negative ion. ⦿ 2. The name of the non-metal negative ion changes its ending to ide. ⚫ One exception – Where negative ions are polyatomic ions, the name remains unchanged. Metal Non-Me Metal Non-Me tal-ide tal-ide NAMING IONIC COMPOUNDS ⦿ Elements with more than one ion charge use a roman numeral in its chemical name to clearly show which ion is being used. CuSO4 (Copper II Sulfate) Ionic Bonding Simulation https://simbucket.com/chemthinkserver/ch emthink/index.html?ib  EXAMPLES ⦿ Na+ and Cl- ⚫ Name the metal first ○ Sodium ⚫ Name the non-metal second and change it’s ending to –ide ○ Chloride ⚫ ***Drop and swap the charges for chemical formula*** + - ○ Sodium chloride = NaCl Na Cl  EXAMPLES ⦿ Ca2+ and Cl- ⚫ Name the metal first ○ Calcium ⚫ Name the non-metal second ○ Chloride ⚫ ***Drop and swap the charges for chemical formula*** ○ Calcium chloride = CaCl2 2+ - Ca Cl  EXAMPLES ⦿ Fe3+ and O2- ⚫ Name the metal first ○ Iron ⚫ Name the non-metal second ○ Oxide ⚫ Use a roman numeral to indicate which iron was used ⚫ ***Drop and swap the charges for chemical formula*** 3+ 2- ○ Iron (III) oxide = Fe2O3 Fe O ION CHARGES AND THE PERIODIC TABLE Patterns Ion Charge Alkali Metals +1 Halogens -1 Generally elements in a group all have the same ion charge (most consistent at either end of the table) Bell Ringer #6 ⦿ What are the properties of ionic compounds? ⦿ Write the chemical name and formula of the following combinations: ⚫ Magnesium and Phosphorus ⚫ Iron (II) and Fluorine ⚫ Potassium and Bromine 3.3 – MOLECULAR COMPOUNDS ⦿ When non-metals combine, they produce a pure substance called a molecule, or molecular compound ⦿ They can be solids, liquids, or gases at room temperature ⚫ sugar = C12H22O11(s) ⚫ water = H20(l) ⚫ hydrogen = H2(g) PROPERTIES OF MOLECULAR COMPOUNDS Low Melting Point Low Boiling Point Good Insulators Poor Conductors Distinct Crystal Shape WRITING FORMULAS FOR MOLECULAR COMPOUNDS ⦿ Rules: ⚫ 1. The first element in the compound uses the element name (just like the ionic compounds do) ⚫ 2. The second element has a suffix – ide – (like the ionic compounds)  WRITING FORMULAS FOR MOLECULAR COMPOUNDS ⚫ 3. When there is more than 1 atom in the formula, a prefix is used which tells how many atoms there are: Number of Atoms Prefix 1 mono 2 di 3 tri 4 tetra 5 penta 6 hexa 7 hepta  WRITING FORMULAS FOR MOLECULAR COMPOUNDS ⚫ 4. Exception to #3 above – when the first element has only 1 atom the prefix mono is not used. ⚫ Examples: ○ CO2 carbon dioxide ○ CCl4 carbon tetrachloride  EXAMPLES ⦿ Using the above rules, molecular compounds are named using this format: ⚫ Prefix + First Element ⚫ Prefix + Second Element (with ‘ide’ ending) ○ CO2 carbon dioxide ○ N2O dinitrogen monoxide ○ N2O3 dinitrogen trioxide ○ NF3 nitrogen trifluoride ○ CCl4 carbon tetrachloride ○ PF5 phosphorus pentafluoride ACHIEVEMENT TEST PREP When two i elements are combined, ii compound is formed. The statement above is completed by the information in row ACHIEVEMENT TEST PREP ⦿ What is the chemical name of a molecular substance that is composed of one carbon atom and four chlorine atoms? ⚫ A. Carbon tetrachlorine ⚫ B. Carbon tetrachloride ⚫ C. Carbon chlorine ⚫ D. Carbon chloride  GIZMO ⦿ Ionic and Molecular Compounds General Outcome 4 Students will apply simplified chemical nomenclature in describing elements, compounds and chemical reactions Specific Outcomes ⦿ describe familiar chemical reactions, and represent these reactions by using word equations and chemical formulas and by constructing models of reactants and products General Outcome 2 Students will describe and interpret patterns in chemical reactions Specific Outcomes ⦿ identify and evaluate dangers of caustic materials and potentially explosive reactions ⦿ observe and describe evidence of chemical change in reactions between familiar materials, by: − describing combustion, corrosion and other reactions involving oxygen − observing and inferring evidence of chemical reactions between familiar household materials ⦿ distinguish between materials that react readily and those that do not ⦿ observe and describe patterns of chemical change, by: − observing heat generated or absorbed in chemical reactions, and identifying examples of exothermic and endothermic reactions − identifying conditions that affect rates of reactions ⦿ identifying evidence for conservation of mass in chemical reactions, and demonstrating and describing techniques by which that evidence is gathered 4.1 – CHEMICAL REACTIONS ⦿ A chemical reaction takes place when two or more substances combine to form new substances ⦿ Launching a space shuttle involves almost 1 500 000 L of liquid hydrogen and 545 000 L of liquid oxygen combining to form water… enough energy is released to put the shuttle into orbit around Earth  CHEMICAL REACTIONS ⦿ The materials at the start of a reaction are called reactants ⦿ The new materials produced by the reaction are called the products reactant reactant product product (yields)  IDENTIFY PRODUCTS & REACTANTS ⦿ Campfire ⚫ Reactants ○ Wood ○ Oxygen ⚫ Products ○ CO2 ○ Water ○ Energy Released (heat) Wood + Oxygen 🡪 CO2 + Water + Energy Released (yields) ⦿ Do “Give it a Try” on page 158 ⦿“Give it a Try” on page 158 Reaction 1 - Reactants: Products: Word Equation: _________________________________________________________________ Reaction 2 – Reactants: Products: Word Equation: _________________________________________________________________ Reaction 3 – Reactants: Products: Word Equation: ________________________________________________________________ EVIDENCE OF CHEMICAL CHANGE Color Formation Change of an Odor Formation Release or of a Solid Absorption or Gas of Heat  EXOTHERMIC & ENDOTHERMIC REACTIONS ⦿ Exothermic Reaction – A chemical reaction that releases heat ⚫ For example – a fireplace (heat is given off) ‘Exit’ ⦿ Endothermic Reaction – A chemical reaction that absorbs heat ⚫ For example – cold packs (heat is absorbed) Global News – Science Teacher Demos ⦿ https://globalnews.ca/video/3970069/co ol-science-how-do-cold-packs-work  CHEMICAL CHANGES INVOLVING OXYGEN Combustion Corrosion Cellular Respiration  COMBUSTION ⦿ A chemical reaction that occurs when oxygen reacts with a substance to form a new substance and give off energy ⦿ In burning, wood reacts with oxygen to give off heat and light and produce carbon dioxide and water  CORROSION ⦿ The slow chemical change that occurs when oxygen in the air reacts with a metal ⦿ A common example of corrosion is rusting ⦿ Rusting occurs when iron reacts with oxygen to form iron oxide  CELLULAR RESPIRATION ⦿ A chemical reaction that takes place in the cells in your body ⦿ Food (glucose) reacts with oxygen to produce energy, water, and carbon dioxide Achievement Test Prep 4.2 – CONSERVATION OF MASS IN CHEMICAL REACTIONS ⦿ The Law of Conservation of Mass: matter is not created or destroyed in a chemical reaction ⦿ In a closed system (no additional material is allowed to enter or leave) the total mass of the products is always the same as the total mass of the reactants  CONSERVATION OF MASS IN CHEMICAL REACTIONS ⦿ In an open system (gas or energy is released into the surroundings) the total mass of the products is sometimes less than the total mass of the reactants ⦿ For example: Adding 10g of Alka-Seltzer to 100g of water results in a mass of 106g, because 4g of carbon dioxide gas was given off Watch Videos 1 and 2 1 - Alka-Seltzer to water experiment 2 - Law explained Video 1 Video 2 Achievement Test Prep 4.3 Factors Affecting the Rate of a Chemical Reaction ⦿ The four factors that can affect the rate of a chemical reaction are: ⚫ The presence of a catalyst ⚫ The concentration of the reactants ⚫ The temperature of the reactants ⚫ The surface area of the reactants Catalysts ⦿ Catalysts – substances that help a reaction proceed faster ⦿ The most common catalyst found in our bodies are enzymes. ⦿ Enzymes help break down food in our bodies at a faster rate Concentration ⦿ The greater the concentration of the reactants, the faster the reaction. ⦿ The increased concentration of the reactants means that there are more atoms of each reactant available to react. Temperature ⦿ The more heat added to the reactants, the faster the reaction. ⦿ The added heat causes the atoms of each reactant to move faster, which increases the chances of them colliding with each other. Surface Area ⦿ The greater the surface area of the reactants, the more area is available for reaction. ⦿ Breaking a substance into smaller pieces would increase the surface area causing the reaction to proceed faster.