1. Mixtures
&
Compounds

2. What is a Compound?
A compound is a substance consisting of two or more elements chemically combined together.

3. Some Examples of Compounds (Textbook pg 78) Their constituent elements
sodium chloride
Water
Copper(II) Sulphate
Carbon Dioxide
Sodium + Chlorine
Hydrogen + Oxygen
Copper + Sulphur
+ Oxygen
Carbon + Oxygen
Their constituent elements

4. Characteristics of Compounds
(Textbook pg 81-83)
A compound has properties that are different from the properties of its constituent elements.

5. Characteristics of Compounds
When a compound is formed, there is usually an exchange of energy (in the form of heat energy or light energy or both) with the surroundings.

6. Characteristics of Compounds
A compound can only be broken down into simpler substances by chemical methods, such as decomposition by heat energy, exposure to light or passing an electric current through it.)

7. Characteristics of Compounds
The different elements in a compound always join together in a fixed proportion by mass.
For example, 1 g of hydrogen combines with only 8 g of oxygen to form 9 g of water.

8. Explain why water is a compound?
Test Yourself
Explain why water is a compound?

9. What is a Mixture?
A mixture consists of two or more substances not chemically combined together.

10. Some Examples of Mixtures
air
soil
blood
sea water
aerated water

11. Characteristics of Mixtures
A mixture has the properties of its components.

12. Characteristics of Mixtures
When a mixture is produced, little or no energy in the form of heat energy or light energy is given out or taken in.

13. Characteristics of Mixtures
A mixture can be separated into its components by physical means such as using a magnet, evaporation, filtration and distillation.

14. Characteristics of Mixtures
The components in a mixture can be mixed in any proportion by mass.

15. Explain why air is a mixture?
Test Yourself
Explain why air is a mixture?

16. Difference between Elements, Compounds and Mixtures
Made up of only one kind of atom
Different elements in a compound combine in a fixed proportion by mass.
The components in a mixture are not mixed in any fixed proportion.

17. Elements Compounds Mixtures
An element is the simplest pure substances
A chemical change takes place when a compound is formed.
No chemical reaction occurs. There is little or no light or heat taken in or given out.
Elements have properties similar to those of their atoms.
A compound has properties which are different from the properties of its constituent elements.
A mixture has the properties of the substances of which it is made.

18. Elements Compounds Mixtures
Elements cannot be broken down.
A compound can only be broken down, by chemical methods, for example. Heating (decomposition) or by passing electricity through it.
A mixture can be separated easily by physical methods, for example, filtration, distillation, evaporation.

19. Word Equations are commonly used for representing chemical reactions.
e.g.
1. iron + sulphur
iron sulphide
2. magnesium + oxygen
magnesium oxide

20. Word Equations are commonly used for representing chemical reactions.
3. oxygen hydrogen
water
4. iron + hydrochloric acid
hydrogen + iron chloride