| A | B |
|---|
| matter | anything that occupies space and has mass |
| chemistry | study of properties of matter & how matter changes |
| physical property | characteristic that can be observed without changing a substance into a new substance |
| chemical property | characteristic that describes how a pure substance changes into a different substance |
| physical change | change that does not change the substance's identity |
| chemical reaction | process in which substances undergo chemical changes and produce new substances |
| precipitate | solid that forms from a solution during a chemical reaction |
| endothermic reaction | reaction that absorbs energy in the form of heat; product gets colder |
| exothermic reaction | reaction that releases energy in the form of heat; product gets hotter |
| chemical equation | short way to show a chemical reaction using symbols & formulas |
| reactant | enters into a chemical reaction; comes before the arrow in an equation |
| product | formed as a result of a chemical reaction; comes after the arrow in an equation |
| conservation of mass | law that states that matter is not created or destroyed in a chemical reaction; why equations must be balanced |
| coefficient | number in front of a symbol or formula that indicates how many molecules or atoms of each reactant or product are involved |
| synthesis | reaction in which two or more substances combine to form a more complex substance |
| decomposition | chemical reaction that breaks down compounds into simpler products |
| replacement | reaction in which one element replaces another in a compound or when two elements in different compounds trade places |
| activation energy | minimum amount of energy needed to get a chemical reaction started |
| concentration | amount of one material in a certain volume of another material |
| catalyst | material that increases the rate of a reaction by lowering the activation energy |
| enzyme | biological catalyst that lowers the activation energy of reactions in cells |
| inhibitor | decreases the rate of a chemical reaction |
| combustion | rapid reaction between oxygen and fuel that results in a fire |
| fuel | releases energy when it burns |
| open system | a system in which matter can enter from or escape to the surroundings |
| closed system | a system in which no matter is allowed to enter or leave |
