- Pure molecular compunds do not conduct, electricity because their molecules are not charged.
- Atoms in molecular substances are joined by covalent bonds.
- Covalent bonding... from electrostatic attraction between the nuclei of the atoms and the electrons shared between them.
- Low melting and boiling point
- Ions held together by attraction between opposite charges
- Giant 3 dimensional structure
- Very strong
- High melting and boiling points
- Conduct when dissolved or molten
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Biosphere and Lithosphere
- Carbohydrates, proteins and DNA are molecules
- Living things mainly made up from the elements, C, H, N and O.
- Chemicals can move between the spheres as part of cycles.
- Elements make up molecules vital for living... Carbohydrates, proteins, fats and DNA.
- Earths outer layer is made from mainly silicon, oxygen and aluminium.
- Silicon dioxide is hard, has a high melting point, is insoluble in water and doesn't conduct electricity.
- Silicon dioxide GIANT structure.
- Atoms held together by strong covalent bonding.
- Some minerals make valuable gem stones because of their rarity and hardness.
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Extraction of metal
- Ores are rocks that contain minerals from which metals can be extracted.
- When a metal loses oxygen it is reduced.
- When carbon gains oxygen it is oxidised.
- Electrolysis - Decomposition of electrolytes with electricity
- Electrolytes conduct electricity but decompose.
- Electrolytes include molten ionic compounds
- Metals form at the negative elctrode (cathode)
- Non-metals form at the positice electrode (anode)
- The properaties of metals affect how they're used... Strength, malleability , melting point and conductivity.
- CYCLE. Mining -> Landfill -> Energy costs
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