1. LESSON 6: CHEMICAL REACTIONS
UNIT 2 lesson 6
Matter and its properties

2. Reading Guide: Lesson 6 Unit 2
Essential Question: How does matter change chemically?
Vocabulary:
Chemical bonds
Chemical reactions
Reactants
Products
Chemical equation
The law of conservation of mass.

3. What happens during a chemical change?
A chemical reaction can be described as new bonds that are formed among the reactants
In a chemical change the substances react causing the reactants to change their chemical identity.
The chemical bonds, which are the forces that hold atoms together, are broken and a new substance has formed.

4. What happens during a chemical reaction?
Energy and Bond breaking:
When particles collide with enough energy, the bonds between the atoms can break. The atoms separate and rearrange forming new bonds.
The substances that react are called reactants. They are part of the chemical change prior to the reaction.
The substances that form as a result of the reaction are called products.

5. What are chemical equations?
Scientists write a chemical reaction in a shorthand form called a chemical equation.
It tells what are the reactants, the products, and the proportions of each substance that is present in the reaction.
Hydrogen + Oxygen water
Reactants are on the left of arrow; products are on the right of arrow.

6. What is the conservation of mass?
A chemical reaction does not create new matter. Instead it forms new bonds among existing atoms .
According to the law of conservation of mass, matter cannot be created or destroyed.
The mass of the products must be the same as the mass of the reactants in the chemical equations.
Atoms are never lost or created in a chemical reaction. They bond to form new substances with other atoms.