electronegativity and polarity

• Pauling electronegativity value

  A value assigned as a measure of the relative attraction of a bonded atom for the pair of electrons in a covalent bond.
• Polar molecule

  A molecule with an overall dipole, having taken into account any dipoles across bonds and the shape of the molecule.
• Polar covalent bond

  A bond with a permanent dipole, having positive and negative partial charges on the bonded atoms.
• Non-polar

  With no charge separation across a bond or in a molecule
• Electronegativity

  A measure of the attraction of a bonded atom for the pair of electrons in a covalent bond
• across the periodic table

  • nuclear charge increases
  • atomic radius decreases
  • electronegativity increases
• electronegativity increases up and across the periodic table
• fluorine is the most electronegative atom and has a Pauling value of 4.0
• electronegativity values can be used to estimate the type of bonding:

  • covalent = 0
  • polar covalent = 0 to 1.8
  • ionic = greater than 1.8