| A | B |
|---|
| reactants | substances that exist before a chemical change or reaction occurs |
| products | substances formed during the chemical change or reaction |
| chemical equation | represents the reactants and products of a chemical change or reaction |
| word equation | describes chemical change using the names of reactants and products |
| coefficients | numbers in front of formulas in chemical equations indicate relative number of molecules or formula units in reaction |
| balanced equation | number of atoms of each element as a reactant equals the number of atoms of that element as a product |
| energy of endothermic reactions | energy term is written on reactant side of equation |
| energy of exothermic reactions | energy term is written on product side of equation |
| phase | form of matter (solid, liquid, or gas) |
| solid phase | represented by (s) after substance formula |
| liquid phase | represented by (l) after substance formula |
| gaseous phase | represented by (g) after substance formula |
| aqueous solution | represented by (aq) after substance formula |
| tincture | represented by (al) after substance formula |
| direct combination (synthesis) reaction | A + B AB; compound or element + compound or element compound |
| decomposition (analysis) reaction | AB A + B; compound two or more elements or compounds |
| single replacement reaction | A + BC B + AC; element + compound element + compound |
| double replacement (exchange of ions) reaction | AB + CD AD + CB |
| catalyst | substance that speeds up a reaction without itself being permanently altered |
| precipitate | solid substance formed by a physical or chemical change in a liquid or gas |
| ionic equations | show what happens to ions that take part in a chemical reaction |
