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4. a pure substance that is formed when two or more different elements combine; can usually be separated into component elements by chemical reaction
8. an element or compound (related words: chemist, chemistry)
10. two or more atoms joined together (related word: molecular)
11. a combination of substances that can be physically separated from one ano
13. the transfer of thermal energy
14. a measure of the average kinetic energy of the atoms in a system, used to express thermal energy in degrees
17. the amount of matter in an object

1. the amount of space that an object occupies, measured in liters or centimeters cubed
2. a weak type of chemical link between a negatively charged atom and a hydrogen atom that is bonded to another negatively charged atom
3. the substances that are formed during a chemical reaction; in a chemical reaction the arrows point toward the product
5. property a characteristic that can be observed (intensive), such as texture, color, odor, melting point, boiling point, density, or measured (extensive) such as mass, length, volume, that is used to describe matter and can be observed or measured without changing its composition
6. change a change in matter that does not affect its chemical composition
7. the smallest unit of an element that has the properties of that element (related word: atomic)
9. a chemical change; a process that changes substances into new substances (related word: chemical change)
11. material that has mass and takes up some amount of space
12. change a chemical reaction; a process that changes substances into new substances (related word: chemical reaction)
15. a pure substance that cannot be broken down into simpler substances by chemical reactions
16. the ability to do work or cause change; the ability to move an object some distance