Chapter 5 Vocab

3. Energy the minimum amount of energy needed to start a chemical reaction.
4. a number placed in front of an element symbol or chemical formula in an equation.
6. of Conservation of Mass states that the total mass of the reactants before a chemical reaction is the same as the total mass of the products after the reaction.
8. a chemical reaction that releases thermal energy.
9. Equation- a description of a reaction using element symbols and chemical formulas.
12. a substance that increases reaction rate by lowering the activation energy of a reaction.
13. a type of chemical reaction in which two or more substances combine and form one compound.
15. the substances produced by the chemical reaction.
16. a substance that slows, or even stops, a chemical reaction.

1. the negative ions in two compounds switch places, forming two new compounds.
2. one element replaces another element in a compound.
5. chemical reactions that absorb thermal energy.
7. Reaction- a process in which atoms of one or more substances rearrange to form one or more new substances.
9. a chemical reaction in which a substance combines with oxygen and releases energy.
10. the starting substances in a chemical reaction.
11. a catalyst that speeds up chemical reactions in living cells.
14. one compound breaks down and forms two or more substances.