electonegativity and polarity

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  • Created by: jp3louis
  • Created on: 09-11-16 19:42
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  • Electronegativity and polarity
    • Polarity
      • Non- polar bonds
        • The bonded electron is shared equally between bonded atoms.
        • A bond is non-polar when the bonded atoms have similar electronegativity numbers.
        • A non-polar bond in H,O or Cl is called a pure covalent bond
        • An example of a pure covalent bond is hydrogen chloride. h has a 2.1 electronegativity whereas cl has 3.0.
      • The separation of charges is called a dipole. A dipole in a polar covalent bond doesn't change so its a permanent dipole
    • Electronegativity
      • Definition: The attraction of a bonded atom for a pair of electrons in a covalent bond.
      • The bonded pair of electrons is shared equally unless
        • The nuclear charges are different
        • Atoms are different sizes
        • Shared electrons may be closer to one nucli than  the other
      • How is it measured?
        • The pauling scale - across the table where the nuclear charge increases and the atomic radius decreases
      • Ionic or covalent?
        • If electronegativity is large, one bonded atom will have a much greater attraction for the shared pair.
        • Covalent = no difference (0) Polar covalent = 0 to 1.8 difference. Ionic is then anything more than 1.8
    • Quick points
      • Big differences in electronega' means the compound is most likely ionic
      • Polar - uneven distribution of charge.
        • When drawing the dipole arrows, the arrows will cancel eachother out(like H2O)
      • Non-polar - bonded e- pair is shared equally.
        • When drawing the dipole arrows, the arrows will not cancel eachother out. Like Co2

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