C5 module

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Earths resources

Atmosphere = layer of gas surrounding the earth

Hydrosphere = mostly made up of water and dissolved compounds

Biosphere = made up of all the living things on earth

Lithosphere = rigid outer layer of the earth made up of the crust and mantle

Chemical cycles = movement of chemicals between different spheres

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Chemicals in Atmosphere

Chemicals that make up the atmosphere are gases at 20 degrees because they have low boiling points.

Gases have weak forces of attraction between molecules so only need small amounts of energy to break forces.

Covalent bonds = strong electrostatic attraction between positive nuclei and shared pair of negative electrons

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Chemicals in Hydrosphere

Ionic compounds = ions are electrostatically attracted to each other to form a 3-D giant crystal lattice with high melting and boiling points. Conduct electricity when dissolved in water.

Salts = dissolved ionic compounds

Polar molecule = water molecule is bent because shared electrons are nearer the oxygen aton than the hydrogen atoms. So atoms have small charges

Water molecule attracted to crystal lattice = ion breaks away = ion moves freely through water.

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Chemicals of Lithosphere

The three most abundant elements in the lithosphere are...

- oxygen

- silicon

- aluminium

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Chemicals of the Biosphere

Contains three groups of molecules....

- carbohydrates = contain carbon, oxygen and hydrogen

- proteins = polymers made from amino acid momomets joined together

- DNA = large, complex molecules

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Extracting useful materials and Electrolysis

Ores = rock containing varying amounts of minerals from which metals can be extracted

Metals less reactive than carbon = extracted by heating with carbon

Metal reduced = lost oxygen Carbon oxidised = gained oxygen

Electrolysis = breaking down of an electroyte using an electric current. Used to extract reactive metals from their ores

Positive ions = negative eletrode Negative ions = positive electrode

When ions get to oppositely charged electrodes they are discharged

Half equations = written to describe what is happening at each of the electodes during electrolysis

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Properties of Metals


- are strong

- are malleable

- high melting points

- conduct electricity

Metal crystal = positively charged metal ions held closely together by "sea" of eletcrons

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