GMS: 8th Grade Science
Unit 13:
 Chemical
Formulas/
Equations
 Law of
Conservation
of Mass
Unit Big Idea (Chemical Reactions which can be shown using chemical equations
produce new substances; but mass is never created or destroyed during these
reactions, the atoms are simply rearranged – Law of Conservation of Mass.)
9.1: Recognize that all matter is made of atoms.
9.2: Identify the common outcome of all chemical changes
9.3: Classify common substances as elements or compounds based on their symbols
or formulas.
9.8: Interpret the results of an investigation to determine whether a physical or
chemical change has occurred.
9.10: Identify the reactants and products of a chemical reaction
9.11: Recognize that in a chemical reaction the mass of the reactants is equal to the
mass of the products (Law of Conservation of Mass)
Students will know:
 Vocabulary to include: 1. chemical reaction, 2. precipitate, 3. diatomic
molecule, 4. chemical formula, 5. subscript, 6. chemical equation, 7.
coefficient, 8. reactant, 9. product, 10. law of conservation of mass, 11.
exothermic reaction, 12. endothermic reaction, 13. law of conservation of
energy, 14. activation energy, 15. inhibitor, 16. catalyst
 Clues that chemical reactions could be occurring
 How to count atoms
 Reactants are materials you start with in chemical reactions
 Products are the substances produced in chemical reactions
 How to balance chemical equations
 Mass cannot be created or destroyed.
 Difference between exothermic and endothermic reactions.
 Factors that change the speed of a chemical reaction
Students will understand that:
 The Law of Conservation of Mass does not allow mass to be created or
destroyed. The amount of mass here on Earth is what has always been here
and will always remain. Mass does, however, undergo chemical changes,
allowing it to change into new substances-- the atoms simply rearrange
themselves when this happens.
 The following analogy: a letter: word: sentence:: chemical symbol: chemical
formula: chemical equation
o A letter in English is like a chemical symbol (element).
o It takes letters to make words. It takes chemical symbols to make
formulas (compounds).
o It takes letters and words to make sentences. It takes chemical
symbols and chemical formulas to make chemical equations.
Students will be able to:
 Count the number of atoms in a chemical formula in order to balance chemical
equations. (Law of Conservation of Mass indicates that the number of atoms
in the reactants must equal the number of atoms of the products.)
 Prove that the mass of the reactants equals the mass of the products through
a lab using baking soda and citric acid. (Law of Conservation of Mass)
 Perform simple experiments to demonstrate two of the four factors
(temperature and surface area) that speed up/slow down chemical reactions.
GMS: 8th Grade Science
Unit 13:
 Chemical
Formulas/
Equations
 Law of
Conservation
of Mass
Unit Big Idea (Chemical Reactions which can be shown using chemical equations
produce new substances; but mass is never created or destroyed during these
reactions, the atoms are simply rearranged – Law of Conservation of Mass.)
9.1: Recognize that all matter is made of atoms.
9.2: Identify the common outcome of all chemical changes
9.3: Classify common substances as elements or compounds based on their symbols
or formulas.
9.8: Interpret the results of an investigation to determine whether a physical or
chemical change has occurred.
9.10: Identify the reactants and products of a chemical reaction
9.11: Recognize that in a chemical reaction the mass of the reactants is equal to the
mass of the products (Law of Conservation of Mass)
Students will know:
 Vocabulary to include: 1. chemical reaction, 2. precipitate, 3. diatomic
molecule, 4. chemical formula, 5. subscript, 6. chemical equation, 7.
coefficient, 8. reactant, 9. product, 10. law of conservation of mass, 11.
exothermic reaction, 12. endothermic reaction, 13. law of conservation of
energy, 14. activation energy, 15. inhibitor, 16. catalyst
 Clues that chemical reactions could be occurring
 How to count atoms
 Reactants are materials you start with in chemical reactions
 Products are the substances produced in chemical reactions
 How to balance chemical equations
 Mass cannot be created or destroyed.
 Difference between exothermic and endothermic reactions.
 Factors that change the speed of a chemical reaction
Students will understand that:
 The Law of Conservation of Mass does not allow mass to be created or
destroyed. The amount of mass here on Earth is what has always been here
and will always remain. Mass does, however, undergo chemical changes,
allowing it to change into new substances-- the atoms simply rearrange
themselves when this happens.
 The following analogy: a letter: word: sentence:: chemical symbol: chemical
formula: chemical equation
o A letter in English is like a chemical symbol (element).
o It takes letters to make words. It takes chemical symbols to make
formulas (compounds).
o It takes letters and words to make sentences. It takes chemical
symbols and chemical formulas to make chemical equations.
Students will be able to:
 Count the number of atoms in a chemical formula in order to balance chemical
equations. (Law of Conservation of Mass indicates that the number of atoms
in the reactants must equal the number of atoms of the products.)
 Prove that the mass of the reactants equals the mass of the products through
a lab using baking soda and citric acid. (Law of Conservation of Mass)
 Perform simple experiments to demonstrate two of the four factors
(temperature and surface area) that speed up/slow down chemical reactions.