Unit 4 Vocabulary

3. A substance that enters into a chemical reaction.
8. A pure substance that cannot be broken down into other substances by chemical or physical means.
12. A change in which one or more substances combine or break apart to form new substances.
14. The process by which molecules at the surface of a liquid absorbs enough energy to change to a gas.
15. The result of an inward pulling among the molecules of a liquid that brings the molecules on the surface closer together; causes the surface to act as if it has a think skin.
17. A number in front of a chemical formula in an equation that indicates how many molecules or atoms of each reactant and product are involved in a reaction.
18. Small, positively charged particles that are found in the nucleus of an atom.
20. A tiny, electrically charged particle that moves around the outside of the nucleus of an atom.

1. A change that alters the form or appearance of a material but does not make the material into another substance.
2. A small particle in the nucleus of the atom with no electrical charge.
4. A neutral group of two or more atoms held together by covalent bonds.
5. The force of attraction that holds two atoms together.
6. The basic particle from which all elements are made.
7. A short, easy way to show a chemical reaction, using symbols.
9. A substance formed as a result of a chemical reaction.
10. A reaction that releases energy , usually in the form of heat.
11. The change in state from a gas to a liquid.
13. A substance made of two or more elements chemically combined in a specific ratio or proportion.
16. The amount of heat required to raise the temperature of 1 kilogram of material by 1 Kelvin; which is equivalent to 1 degree Celsius.
19. The part of a solution that is usually present in the largest amount and dissolves the solute.