Chapter 4 Vocab

10. When two or more elements or compounds combine to make a more complex substance.
11. When one element replaces another element in a compound, or if two elements in different compounds trade places.
12. The biological catalysts in your body that help some chemical reactions occur at body temperature.
13. Something that increases the reaction rate by lowering the activation energy needed.
14. A change in matter that produces one or more new substances.
16. A way to show a chemical reaction, using symbols instead of words.
17. A reaction that occurs when compounds break down into simpler products.
18. A solid that forms from liquids during a chemical reaction.
20. The principle that states that during a chemical reaction matter is not created nor destroyed.

1. A number placed in front of a chemical formula in an equation.
2. The minimum amount of energy needed to start a chemical reaction.
3. A material used to decrease the rate of a chemical reaction.
4. When the energy released as the products form is greater than the energy required to break the bonds of the reactants.
5. Substance that undergo chemical changes.
6. The amount of a substance in a given volume.
7. Any change that alters the form or appearance of a substance but does not change it into another substance.
8. When more energy is required to break the bonds of the reactants than is released by the formation of the products.
9. When matter can enter from or escape to the surroundings.
15. The new substances that form in a chemical reaction.
19. Somewhere that matter does not enter or leave.