| Term | Definition |
| matter | anything that has mass and takes up space |
| mass | describes the amount of matter in an object |
| weight | a measure of the gravitational force on an object |
| volume | the amount of space an object occupies |
| density | a measure of the amount of mass in a given volume |
| physical property | a characteristic of a substance that can be observed and measured without changing the identity of the substance |
| chemical property | a substance's ability to change into a new substance with different properties |
| physical change | a change that affects one or more physical properties of a substance |
| chemical change | one or more substances change into entirely new substances with different properties |
| atoms | the smallest unit of an element that maintains the properties of that element |
| element | made up of one or more of the same kind of atom chemically combined |
| compound | made up of different kinds of atoms chemically combined |
| mixture | contains a variety of elements and compounds that are not chemically combined with each other |
| pure substance | a substance that has definite physical and chemical properties such as appearance, melting point, and reactivity |
| heterogeneous | a mixture that does not have a uniform composition |
| homogeneous | a mixture in which substances are evenly spread throughout |
| solid | substance that has definite volume and shape |
| liquid | has a definite volume but not a definite shape |
| gas | does not have a definite volume or shape |
| freezing | the change in state in which a liquid becomes a solid |
| melting | change of state from a solid to a liquid |
| evaporation | particles gain enough energy that they escape from the surface of the liquid and become a gas |
| boiling | a rapid change from a liquid to a gas |
| condensation | change of state from a gas to a liquid |
| sublimation | the change from a solid state directly into a gas |
| deposition | the change in state from a gas directly to a solid |
