Chapter 5

5. , The minimum amount of energy needed to start a chemical reaction.
7. , Amount of substance in a given volume.
9. , The energy that releases heat.
11. , The energy that absorbs heat.
13. , An alter in appearance of a substance
15. , When two or more elements or compounds combine to make a more complex substance.
17. , When compounds breaks down into simpler products.
19. equation , A way to show a chemical reaction using symbols
20. , Matter doesn't enter or leave.

1. , A solid that forms from liquids during a chemical reaction.
2. , A material that is used to decrease the rate of a chemical reaction.
3. , During a chemical reaction, matter in neither created nor destroyed.
4. , substances that undergo the chemical change
6. , Tiny cells in our bodies that are reactants helping occur at body temperature.
8. , Increases the reaction rate by lowering activation energy.
10. , a number placed in front of a chemical formula in an equation.
12. , matter can enter or escape to the surroundings
14. , A change in matter that produces 1 or more new substances
16. , When one element replaces another element in a compound.
18. , The new substance formed after a chemical change.