Chemical reactions

2. is the minimum amount of energy needed to start a chemical reaction
5. the cells in your body contain thousands of biological catalysts called that help these reactions occur at body temperature
7. increases the reaction rate by lowering the activation energy needed
8. a material used to decrease the rate of chemical reaction is an
9. is a solid that forms from liquids during a chemical reaction
11. matter can enter from or leave
13. matter does not enter or leave
14. a change in matter that produces one or more new substances or a chemical reaction
16. more energy is required to break the bonds of the reactants then is released by the formation of the products
18. this principle states that during a chemical reaction matter is not created or destroyed.
19. a reaction occurs when compounds break down into simpler products.
20. is a number placed in front of a chemical formula in an equation

1. the energy released as the products form is greater than the energy required to break the bonds of the reactants
3. substances that undergo the chemical changes are called.
4. is the amount of a substance in a given volume
6. is any change that alters the from or appearance of a substance but does not change it into another substance.
10. if two elements in different compounds trade places the reaction is called
12. in chemistry when two or more elements or compounds combine to make a more complex substance the reaction is classified as.
15. is a way to show a chemical reaction using symbols instead of words.
17. the new substances that form are the.