Science

3. The negative ions in two compounds switch places, forming two new compounds.
7. The starting substances in a chemical reaction.
9. A chemical reaction that releases thermal energy.
11. One element replaces another element in a compound.
14. A description of a reaction using element symbols and chemical formulas.
16. A substance that slows, or even stops, a chemical reaction.

1. The total mass of the reactants before a chemical reaction is the same as the total mass of the products after the reaction.
2. The substances produced by the chemical reaction.
4. A substance that increases reaction rate by lowering the activation energy of a reaction.
5. The minimum amount of energy needed to start a chemical reaction.
6. A process in which atoms of one or more substances rearrange to form one or more new substances.
8. A chemical reaction in which a substance combines with oxygen and releases energy.
10. A number placed in front of an element symbol or chemical formula in an equation.
11. A type of chemical reaction in which two or more substances combine and form one compound.
12. Chemical reaction that absorbs thermal energy.
13. One compound breaks down and forms two or more substances.
15. A catalyst that speeds up chemical reactions in living cells.