C4 - Ionic and covalent bonding

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  • Created by: Naomi
  • Created on: 23-01-13 17:42
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  • Ionic and covalent bonding
    • Why do atoms form bonds?
      • Atoms with an outer shell of eight electrons have a stable electronic structure
      • Atoms want to have a full outer shell and be stable
        • Atoms can be made stable by:
          • Transferring electrons (ionic bonding)
          • Sharing electrons (covalent bonding)
    • Ionic bonding
      • Ionic bonding happens between a metal and a non metal
        • Metal atoms lose electrons to get a stable electronic structure
          • If an atom loses electrons, a positive ion is formed. This is because there are more protons than electrons
        • Non-metal atoms gain electrons to get a stable electronic structure
          • If atoms gain electrons a negative ion is formed. This is because there are more electrons than protons
        • During ionic bonding the metal atom becomes a positive ion and the non-metal becomes a negative ion
          • The positive and negative ions then attract one another
      • They form giont ionic lattices and are always solid
        • Positive ions have a strong electrostatic attraction to the negative ions
      • They have high melting points as there are strong attractions between positive and negative ions
      • They cannot conduct electricity when solid because the ions cannot move, so there are no free elecrons
      • They conduct electricity when molton or in a solution because the ions are free to move
    • Covalent bonding
      • Non metals can share electron pairs between atoms, this is known as covalent bonding
      • They leave no free electrons so the substance cannot conduct water
    • Some ions (charged particles) are made from several atoms joined together. They will still form ionic compounds
      • Carbonate: CO
      • Sulphate: SO
      • Nitrate: NO
      • Ammonium: NH
      • Hydroxide: OH
      • When you use these ions put them in brackets if you need more than one of them


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