Question

this section describes what happens to chemical bonds during chemical reactions. it also explains how energy changes affect chemical reactions and describes the importance of enzymes.
chemical reactions

1. what is a chemical reaction?
2. complete the table about chemicals in a chemical reaction.

chemicals in a chemical reaction

chemicals	definition
products

1. chemical reactions always involve changes in chemical

energy in reactions

1. what is released or absorbed whenever chemical bonds form or are broken?
2. what do chemical reactions that absorb energy need to occur?
3. chemists call the energy needed to get a reaction started the
4. complete the graph of an energy - releasing reaction by adding labels to show the energy of the reactants, the energy of the products, and the activation energy.

energy - releasing reaction
| energy |
|--|
| course of reaction |

Explanation:

Step1: Define chemical reaction

A chemical reaction is a process that changes one set of chemicals into another set of chemicals.

Step2: Define reactants and products

Reactants are the starting substances in a chemical reaction. Products are the substances produced by a chemical reaction.

Step3: Identify change in chemical reactions

Chemical reactions always involve changes in chemical bonds.

Step4: Determine energy change in bond - formation/breakage

Energy is released or absorbed whenever chemical bonds form or are broken.

Step5: Find requirement for endothermic reactions

Chemical reactions that absorb energy need a source of energy to occur.

Step6: Name energy to start a reaction

Chemists call the energy needed to get a reaction started the activation energy.

Step7: Label energy - releasing reaction graph

On the graph: The horizontal line at the lower - left represents the energy of the reactants. The horizontal line at the lower - right represents the energy of the products. The vertical distance from the energy of the reactants to the peak of the curve is the activation energy.

Answer:

1. A process that changes one set of chemicals into another set of chemicals.
2. Reactants: Starting substances in a chemical reaction. Products: Substances produced by a chemical reaction.
3. Bonds
4. Energy
5. A source of energy
6. Activation energy
7. Label the lower - left horizontal line as "Energy of reactants", the lower - right horizontal line as "Energy of products", and the vertical distance from the energy of the reactants to the peak of the curve as "Activation energy".