Chapter Menu Lesson 1:Chemical Properties and ChangesChemical Properties and Changes Lesson 2:Chemical EquationsChemical Equations Lesson 3:Energy and Chemical ChangeEnergy and Chemical Change Click on a hyperlink to view the corresponding lesson.

chemical property chemical change dissolving 8.1 Chemical Properties and Changes

Ability to Change In a chemical change, the properties that give a substance its identity change. 8.1 Chemical Properties and Changes Properties of matter help identify objects. Properties are either physical or chemical. What properties do elements have?

Ability to Change (cont.) A chemical property is the ability or inability of a substance to combine with or change into one or more new substances. 8.1 Chemical Properties and Changes

Chemical Properties Examples of chemical properties include burning or rusting. Some substances do not react. 8.1 Chemical Properties and Changes

Physical Properties Physical properties can be observed without changing the substance. 8.1 Chemical Properties and Changes

Chemical and Physical Changes Chemical changes change one substance into another substance. Usually chemical changes cannot be easily reversed. 8.1 Chemical Properties and Changes Property Changes

Forming New Substances All chemical changes produce substances that are different from the starting substances. –A compound is decomposed into its elements. –Two elements join to form a compound. 8.1 Chemical Properties and Changes

Physical Changes A physical change is a change in which the properties of a substance change but the identity of the substance remains the same. Dissolving is a process in which substances mix evenly with one another. 8.1 Chemical Properties and Changes

Lesson 1 Review Which is a chemical change? Aboiling Bburning Cdissolving Dmelting 8.1 Chemical Properties and Changes 1.A 2.B 3.C 4.D

Lesson 1 Review Which is NOT a chemical change? Asodium metal and chlorine gas react to form salt Bsalt dissolving in water Cpaper burning Diron rusting 8.1 Chemical Properties and Changes 1.A 2.B 3.C 4.D

Lesson 1 Review Which is NOT a physical change? Amelting Bboiling Cdissolving Dburning 8.1 Chemical Properties and Changes 1.A 2.B 3.C 4.D

End of Lesson 1

law of conservation of mass reactants products diatomic molecule coefficient 8.2 Chemical Equations

Is matter conserved in chemical reactions? Chemical equations show that in chemical reactions, atoms rearrange, but no atoms are gained or lost. 8.2 Chemical Equations

Antoine Lavoisier Lavoisier invented a balance to make more precise measurements. He also determined that the mass before and after a chemical reaction was the same. 8.2 Chemical Equations

Conservation of Mass The law of conservation of mass states that the total mass before a chemical reaction is equal to the total mass after the reaction. 8.2 Chemical Equations

Writing a Chemical Equation Reactants are the starting materials in a chemical reaction and are placed on the left side. Products are the ending materials in a chemical reaction and are placed on the right side. 8.2 Chemical Equations

Word Equations “Tin + oxygen → tin oxide” reads as “tin plus oxygen produces tin oxide.” Word equations can be long and do not show that mass is conserved. 8.2 Chemical Equations

Elements, Compounds, and Molecules Instead of writing long word equations, scientists use symbols and formulas. –Symbols represent atoms. –Formulas represent molecules. –Molecules may be elements or compounds. 8.2 Chemical Equations

Elements, Compounds, and Molecules (cont.) Some elements are diatomic, that is, they contain two atoms. 8.2 Chemical Equations Molecules may also contain two different elements, such as hydrogen and oxygen in a water molecule.

Elements, Compounds, and Molecules (cont.) 8.2 Chemical Equations

Chemical Equations Use the symbols and formulas instead of words. 8.2 Chemical Equations

Balancing a Chemical Equation Atoms are neither gained nor lost in a reaction, so both sides of the equation must have the same number of atoms. 8.2 Chemical Equations

Counting Atoms A subscript tells how many atoms of an element are in one molecule. 8.2 Chemical Equations A coefficient tells how many atoms, molecules, or formula units are in a reaction.

8.2 Chemical Equations Comparison of Coefficients and Subscripts

Writing Balanced Equations Step 1Determine the correct symbols and formulas for reactants and products. Step 2Write reactant symbols and formulas to the left of an arrow and product symbols and formulas to the right. Step 3Count the number of each kind of atom on both sides. Step 4Use coefficients to make the number of each kind of atom the same on both sides of the arrow. Step 5Check to see that each kind of atom balances. 8.2 Chemical Equations

Equations for Common Chemical Reactions Reaction of methane: CH 4 + O 2 → CO 2 + H 2 O balance hydrogen CH 4 + O 2 → CO 2 + 2H 2 O balance oxygen CH 4 + 2O 2 → CO 2 + 2H 2 O 8.2 Chemical Equations

Equations for Common Chemical Reactions (cont.) Baking soda and vinegar: NaHCO 3 + HC 2 H 3 O 2 → CO 2 + H 2 O + NaC 2 H 3 O Chemical Equations

Using Parentheses with Formulas When counting atoms inside parentheses, the subscript multiplies all atoms inside. Ca + H 2 O → Ca(OH) 2 + H 2 Ca + 2H 2 O → Ca(OH) 2 + H Chemical Equations

Lesson 2 Review Which is a diatomic molecule? AO2AO2 BH2OBH2O CCH 4 DNDN 8.2 Chemical Equations 1.A 2.B 3.C 4.D

Lesson 2 Review What is potassium bromide (KBr)? Aan element Ba mixture Ca compound Da diatomic molecule 8.2 Chemical Equations 1.A 2.B 3.C 4.D

Lesson 2 Review In the following equation, which is a reactant? Ca +2H 2 O → Ca(OH) 2 + H 2 AH2AH2 B(OH) 2 CCa Dnone of the above 8.2 Chemical Equations 1.A 2.B 3.C 4.D

End of Lesson 2

8.3Energy and Chemical Change law of conservation of energy exothermic process endothermic process

Energy and Chemical Reactions In chemical reactions, energy is either absorbed or released. In chemical reactions, atoms rearrange. Rearrangement involves some form of energy, usually thermal energy. 8.3 Energy and Chemical Change

Light From Chemical Reactions Some reactions give off light with almost no thermal energy. Cold light occurs at room temperature. 8.3 Energy and Chemical Change

Conservation of Energy Energy is stored in reacting molecules. The law of conservation of energy states that energy cannot be created or destroyed, simply changed from one form to another. 8.3 Energy and Chemical Change

Chemical Bonds Molecules have chemical energy stored in their bonds. Energy is stored in the food that you eat and transferred to your cells. 8.3 Energy and Chemical Change

Net Release of Energy When atoms rearrange, bonds are broken and new bonds form. –Breaking bonds requires energy. –Forming bonds releases energy. 8.3 Energy and Chemical Change

Net Release of Energy (cont.) An exothermic process releases energy. The products in an exothermic reaction have less energy than the reactants. 8.3 Energy and Chemical Change

Net Release of Energy (cont.) An endothermic process absorbs energy. The products in an endothermic reaction have a higher energy than the reactants. 8.3 Energy and Chemical Change

Lesson 3 Review Products have a higher energy level than the reactants in an endothermic reaction. AFalse BTrue 8.3 Energy and Chemical Change 1.A 2.B

Lesson 3 Review ____ bonds ____ energy. ABreaking; releases BBreaking; requires CForming; requires DIonic; release 8.3 Energy and Chemical Change 1.A 2.B 3.C 4.D

Lesson 3 Review The law of ____ states that energy is neither created nor destroyed in a chemical reaction. Aconservation of mass Bdefinite proportions Cconservation of matter Dconservation of energy 8.3 Energy and Chemical Change 1.A 2.B 3.C 4.D

End of Lesson 3

Chapter Resources Menu Click on a hyperlink to view the corresponding feature. Chapter Assessment California Standards Practice Image Bank Science Online Interactive Table Virtual Lab BrainPOP

Which is a chemical change? Acopper turning green from exposure to air Bdrying clothes Cice melting Dnone of the above Chapter Assessment 1 1.A 2.B 3.C 4.D

Which is a chemical property? Aboils at 100°C Bhas a volume of 500 ml Cdoes not rust Dhas a luster Chapter Assessment 2 1.A 2.B 3.C 4.D

Which does NOT describe an exothermic reaction? AThere is a net release of energy. BThe reactants have a higher energy than the products. CThe reactants are lower in energy than the products. DThe products are less stable than the reactants. Chapter Assessment 3 1.A 2.B 3.C 4.D

What is the coefficient of H 2 O? Ca + 2H 2 O → Ca(OH) 2 + H 2 A1A1 B0B0 C4C4 D2D2 Chapter Assessment 4 1.A 2.B 3.C 4.D

How many (OH) molecules are in the products? Ca + 2H 2 O → Ca(OH) 2 + H 2 A1A1 B2B2 C3C3 D4D4 Chapter Assessment 5 1.A 2.B 3.C 4.D

In a chemical reaction, which law states the products have the same mass as the reactants? ALaw of Conservation of Water BLaw of Conservation of Energy CLaw of Conservation of Mass DLaw of Conservation of Particles CA Standards Practice 1 SCI 5.b 1.A 2.B 3.C 4.D

Energy is ____ in exothermic reactions. Aabsorbed Bcreated Creleased Dstored CA Standards Practice 2 SCI 5.c 1.A 2.B 3.C 4.D

If an equation is balanced, the number of atoms in the products is ____ the number of atoms in the reactants. Agreater than Bless than Cequal to Dnone of the above CA Standards Practice 3 SCI 3.b 1.A 2.B 3.C 4.D

Which of the following is a physical change? Ahydrogen burning Biron rusting Ccopper turning green when exposed to air Dnone of the above CA Standards Practice 4 SCI X.X 1.A 2.B 3.C 4.D

Symbols represent ____ and ____ represent molecules. Aelements; formulas Bformulas; equations Cmolecules; formulas Delements; equations CA Standards Practice 5 SCI 3.f 1.A 2.B 3.C 4.D

Image Bank

Interactive Table Comparison of Coefficients and Subscripts

End of Resources