Chemical Changes in Matter

2. a number placed in front of a a chemical formula in an equation
4. change any change that alters the form or appearance of a substance but that does not make the substance into another substance
5. property a characteristic of a substance that can be observed without changing the substance into another substance
9. the study of matter and how matter changes
12. system matter can enter from or escape to the surroundings
13. anything that has mass and takes up space
14. when the reaction is complete, this is the new substances
16. system matter is not allowed to enter or leave
18. a material that increases the rate of a reaction by lowering the activation energy
19. breaks down compounds into simpler products
21. when two or more elements or compounds combine to make a more complex substance
22. reaction a reaction in which energy is absorbed
24. reaction a change in matter that produces one or more new substances
25. a rapid reaction between oxygen and a substance called fuel

1. of mass during a chemical reaction, matter is not created or destroyed
2. the amount of a substance in a given volume
3. when one element replaces another in a compound or when two elements in different compounds trade places
6. the substances you have at the beginning
7. energy the minimum amount of energy needed to start a chemical reaction
8. a solid that forms from solution during a chemical reaction
10. the cells in your body that contain biological catalysts
11. a material that releases energy when it burns
15. a material used to decrease the rate of reaction
17. reaction a reaction that releases energy in the form of heat
20. equation a short, easy way to show a chemical reaction, using symbols instead of words
23. property a characteristic of a substance that describes its ability to change into other substances