Electron Domains

Electron Domains

The VSEPR (Valence Shell Electron Pair Repulsion) Theory states that molecules will attain whatever shape keeps the valence electrons of the central atom as far apart from one another as possible.

• Unshared pairs of electrons on the central atom determine the shape.
• Electron pairs REPEL each other.

• Electron domain: The space occupied by valence electrons in a molecule, either a bonded pair(s) or a lone pair. Electron domains affect the overall shape of a molecule.
• Electron domain theory: The idea that every electron domain in a molecule is as far as possible from every other electron domain in that molecule.
  • 4 bonding pairs, 0 lone pairs- tetrahedral shape (109.5 degrees)
  • 3 bonding pairs, 1 lone pair- trigonal pyramidal (105 degrees)
  • 2 bonding pairs, 2 lone pairs- bent
  • 2 bonding pairs (double bonds), 0 lone pairs- linear (180 degrees)

    • Lone pairs occupy more space than bonding electron pairs.

    • Double bonds occupy more space than single bonds.