1. Lesson: Mixtures & Compounds

2. Mixture: A mixture is made of two or more substances mingled together but not chemically combined.
Air is a mixture
Sea water is a mixture

3. Air contains:
nitrogen
oxygen
carbon dioxide

4. Sea-water contains: water salt
The Dead Sea has a high concentration of salt.

5. Compound:
A compound is formed when two or more elements chemically combined. e.g. water, CO2
Carbon dioxide gas is a compound formed when one atom of carbon is combined chemically with two atoms of oxygen (CO2).
oxygen
carbon

6. A compound is formed when two or more elements combine chemically
oxygen
Water is a compound formed when one atom of oxygen is combined chemically with two atoms of hydrogen (H2O).
hydrogen

7. Examples of compounds Water (H2O) Carbon dioxide (CO2)
Magnesium oxide (MgO)
Iron sulfide (FeS)
How many atoms are in each molecule of the above compounds?

8. Differences between mixtures and compounds
Made of 2 or more substances
Is a single substance
Properties are the same as the properties of the substances mixed together
Properties are different to the elements involved
Generally easy to separate
Difficult to separate

9. A compound is a completely new substance with its own properties.
Water (H2O) is a liquid that can put out fires.
Yet, the elements that make it are very different.
Hydrogen (H2) is an explosive gas.
oxygen
Oxygen (O2) is gas needed for burning.
hydrogen

10. A compound is a completely new substance with its own properties.
Carbon dioxide (CO2) is a colourless gas used to put out fires.
oxygen
Carbon (C) is a black solid.
Oxygen (O2) is needed for burning.
carbon

11. A compound is a completely new substance with its own properties.
Magnesium oxide (MgO) is a dull
white solid.
Magnesium (Mg) is a soft shiny metal.
Oxygen (O2) is needed for burning.

12. A compound is a completely new substance with its own properties.
Iron (Fe) is a metal
that is attracted to magnets.
Sulfur (S) is a bright yellow solid.
Iron sulfide (FeS) is a grey solid
that is not attracted to magnets.

13. Review Questions 1. Is air a mixture or a compound?
2. What elements is carbon dioxide made from?
3. Name one difference between a compound and a mixture.
4. Hydrogen is explosive and oxygen is needed for burning. What compound can both of these elements make?

14. Question to think about!
How could you check if a substance was an element or a compound?
oxygen
hydrogen