1. Chemical Changes Word equations

2. Chemical reactions – What to look for
There may be a change of colour

3. Chemical reactions – What to look for
There may be a gas given off (bubbles)

4. Chemical reactions – What to look for
There may be an energy change (gets hotter or colder)

5. Chemical reactions – What to look for
New substances are formed, and the change is usually difficult to reverse

6. Learning for today
1) Know the meanings of the words reactant, product and word equation
2) Be able to write word equations for chemical reactions

7. Physical? OR
Chemical?

8. Physical or chemical – how can we tell?

9. Part 1 – Reactants and Products
If we made a cake we would start with the ingredients,
mix and cook them to give us a finished cake
The ingredients are the reactants, and the finished cake is the product.

10. Activity Task: 1) Copy the table
In a chemical reaction we start with one set of chemicals called the reactants, a reaction happens and we end up with another set, called the products.
Task:
1) Copy the table
2) Think of some examples from the last lesson, and from your book, of reactants and products
3) Fill in your table
Experiment
Reactants
Products
Baking a Cake

11. Eggs + flour + milk + butter Cake
Part 2 - Word Equations
To show what is happening during a chemical reaction we can write a word equation
Eggs + flour + milk + butter Cake

12. Eggs + flour + milk + butter Cake
Word Equations
For this reaction the word equation is
Eggs + flour + milk + butter Cake
Copy this down
We use word equations to show what is happening in a
chemical reaction. The reactants go on the left side and the
products on the right. We use an arrow not an equals sign (=).
The arrow means “reacts to form”

13. Your Turn… When methane is burned in oxygen it
produces a gas, carbon dioxide and water.
What are the reactants?
What the products?
What is the word equation?

14. Your Turn… When methane is burned in oxygen it
produces a gas, carbon dioxide and water.
What are the reactants?
What the products?
What is the word equation?
Methane + oxygen  carbon dioxide + water

15. Task Using the work card, work out what are the
reactants and products then complete the
word equations for the chemical reactions

16. How have you done?
1) Define and give examples of the words reactant and product and word equation
2) Give an example of a word equation for a chemical reaction that we did last lesson.