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Ch. 2 Holt
Matter
| Term | Definition |
|---|---|
| chemistry | the scientific study of the composition, structure, and properties of matter and the changes that matter undergoes. |
| matter | anything that has mass and takes up space. |
| element | a substance that cannot be separated or broken down into simpler substances by chemical means. |
| atom | the smallest unit of an element that maintains the properties of that element. |
| compound | a substance made of two or more different elements that are chemically combined. |
| molecule | the smallest unit of a substance that keeps all of the physical and chemical properties of that substance. |
| chemical formula | a combination of chemical symbols and numbers to represent a substance ` |
| pure substance | a sample of matter, either a single element or a single compound that has definite chemical and physical properties |
| mixture | a combination of two or more substances that are not chemically combined |
| melting point | the temperature and pressure at which a solid becomes a liquid. |
| boiling point | the temperature at which a liquid becomes a gas |
| density | the ratio of the mass of a substance to the volume of a substance |
| re activity | the ability of a substance to combine chemically with another substance |
| flammability | the ability to react in the presence of oxygen and burn when exposed to a flame |
| physical change | a change of matter from one form to another without a change in chemical properties |
| chemical change | a change that occurs when a substance changes composition by forming one or more new substances |