Chemistry. Chemicals of the natural environment C5

Covalent Bonding, Ionic Bonding, Metallic Bonding...

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  • Created by: Amy
  • Created on: 24-06-11 09:13

Covalent Bonding

COVALENT BONDING

  • 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

IONIC BONDING

  • 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

Biosphere

  • 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.

Lithosphere

  • 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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