| Matter | is anything that has mass and takes up space. |
| 3 principal states of matter | solids, liquids, and gases. |
| Characteristic properties | for a give substance never changes, they can be used to identify unknown matter. |
| Boiling point | is the temperature at which a substance changes from a liquid to a gas. |
| Melting point | is the temperature at which a solid changes from a solid to a liquid. |
| Physical changes | alter the form of a substance, but not its identity. |
| Chemical changes | are when substances combine or break apart to form new substances. |
| Chemical activity | is a characteristic property of a substance that indicates its ability to undergo a specific chemical change. |
| Matter | can be classified into two general categories: mixture and pure substances. |
| Pure substances | is made of only one kind of matter and has definite properties. |
| Elements | are substances that cannot be broken down in to other substances by any physical or chemical means. |
| Compound | is a substance made of two or more elements that are chemically combined. |