1. The living and non-living components of the Earth contain mixtures
The Chemical Earth (8.2.1)
The living and non-living components of the Earth contain mixtures

2. Elements, Compounds and Mixtures
Elements are pure substances made up of only one type of atom.
Compounds are pure substances made up of two or more atoms, chemically combined in a fixed ratio.
Mixtures are impure substances made up of two or more substances, physically combined in no fixed ratio.

3. Elements At present there are 112 known elements. 88 are metals.
18 are non metals.
There are 6 semi metals or metalloids.
92 are naturally occurring the remainder are man made
Isotopes are elements with different atomic masses.

4. Compounds
Compounds are made up of two or more elements chemically combined in a fixed ratio.
Ionic compounds are made of elements that “give away” or “take in” electrons forming electrically charged particles called ions.
Covalent compounds are made up of elements that “Share electrons”.
Compounds have a chemical formula which does not vary.

5. Mixtures
Mixtures are impure substances because they have no exact component parts, ie. They have no chemical formula.
Mixtures can be “easily” separated
Salt separated by evaporation of sea water.

6. The SPHERES of the Earth
Hydrosphere – All of the water on earth makes up the hydrosphere. Most of the water on earth is a mixture of: Compounds such as salt. Gases such as oxygen. Living matter such as plants and animals. Particulate matter such as silt, clay, etc.

7. Biosphere – All life on earth makes up the biosphere
Biosphere – All life on earth makes up the biosphere. As in the hydrosphere, the biosphere is a gigantic mixture of life: Plants Animals Viruses Fungi

8. Lithosphere – makes up the crust of the earth
Lithosphere – makes up the crust of the earth. Many mixtures must be separated to get needed materials from the earth. Metals Fresh water Sulfur
Artesian water
Sulfur mining

9. Atmosphere – The atmosphere is a mixture of many gases, and solids:
Oxygen
Nitrogen
Helium
Dust

10. Separating mixtures
Mixtures are Physically combined combinations of particles. This means that separations will involve methods using the physical characteristics of the substances and relatively low energy input.
Filtering/decanting – particle size
Evaporation/distillation – boiling points
Density – centrifugation/decanting

11. Homogeneous mixture - any combination of substances that has uniform composition and properties; a mixture that is uniform throughout.
Ex. Salt water, 2-stroke petrol
Heterogeneous mixtures – any combination of substances that does not have uniform composition and properties; a mixture of physically distinct substances with different properties.
Ex. Soil and water, dust in air

12. Methods of separation
Filtration – for heterogeneous mixtures. Uses particle size and a media to separate solids from liquids or gases.

13. Two common methods of filtration
Two common methods of filtration. One used in the kitchen to separate peas, etc. from water, the other to separate shell grit of different sizes.

14. Laboratory distillation apparatus
Evaporation/distillation – used to separate liquid mixtures, gaseous mixtures or liquids from dissolved solids. With liquid mixtures, low boiling point liquids evaporate first leaving higher boiling point liquids behind. For solutions of solids and liquids, the liquid evaporates leaving the solid behind.
Distillation of air

15. Chromatography – a method of separation where a homogeneous mixture such as ink is passed along a stationery media such as paper using a solvent. The paper causes colours to “stick” causing a separation.

16. Gravimetric Analysis
This is a way of determining how much of a material is in a mixture.
It involves the mass of the original material, an ore for example, and the final mass of the mineral desired.
Ex. If one kilo of the ore of iron, hematite, contains 300g of pure iron oxide and 700g of waste, the ore is 30% pure iron oxide.
See Practical – Separation techniques with this unit.

17. compounds
Compounds are chemically combined arrangements of atoms in a fixed ratio. To separate the particles of a compound requires large amounts of energy, in many cases, to overcome the bonding strength of atoms in the compound.
Basic Oxygen Steelmaking (BOS)
Requires huge energy input to produce “pure” iron.

18. Questions Write the formulas for: Magnesium oxide Aluminium chloride
Potassium sulfate
Categorize the following as element, compound or mixture and justify your choice. (you may need to research each)
Water, sea water, copper pipe, oxygen, milk, smoke, petrol.
How does chromatography work?
Explain why are compounds harder to separate than mixtures.