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
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
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.
Chemicals of Lithosphere
The three most abundant elements in the lithosphere are...
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
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
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