Science Vocab chapter 4

3. the new substances that form.
5. occurs when compounds break down into simpler products.
6. increases the reaction rate by lowering the activation energy needed.
8. matter does not enter or leave
11. a solid that forms from liquids during a chemical reaction.
14. substances that undergo the chemical changes.
16. matter can enter from or escape to the surroundings.
17. more energy is required to break the bonds of the reactants than is released by the formation of the products.
19. any change that alters the form or appearance of a substance but does not change it into another substance.
20. A material used to decrease the rate of a chemical reaction is an...

1. states that during a chemical reaction matter is not created or destroyed.
2. a number placed in front of a chemical formula in an equation.
4. A change in matter that produces one or more new substances.
7. the minimum amount of energy needed to start a chemical reaction.
9. the energy released as the products form is greater than the energy required to break the bonds of the reactants.
10. in chemistry when two or more elements or compounds combine to make a more complex substance, the reaction is classified as...
12. the cells in your body contain thousands of biological catalysts called...
13. a way to show a chemical reaction, using symbols instead of words.
15. the amount of a substance in a given volume.
18. when one element replaces another element in a compound, or if two elements in different compounds trade places, the reaction is a replacement.