8.4 Polar Bonds and Molecules

• Dipole moment


  The measure of the polarity of a bond
• Covalent bonds can be polar or non-polar
• Bonding pairs of electrons


  Pulled by the nuclei of the atoms that share those e-
• Electronegativity


  An atom's ability to attract electrons
• 1. Cl dipole moment


  Indicates that Cl is more negative than H
• Polar covalent bonds

  Electrons are shared unequally
• Polar bond

  When atoms pull the e- unequally
• Non-polar covalent bonds

  Electrons are shared equally among the atoms
• Electronegativity ranges from 0.0-4.0
• Electronegativity values

  • H=2.1
  • Cl=3.2
• Dipole moment points

  Towards the element with higher electronegativity
• Non-polar bond


  When atoms pull the e- equally
• 1. Cl has a dipole moment
• WATER IS VERY POLAR
• Polar molecule


  Molecule with an overall charge
• Carbon dioxide is a non-polar molecule despite its 2 polar bonds
• Polar molecule

  One end of the molecule is slightly negative and the other end is slightly positive
• Polar molecules


  Show stronger intermolecular forces than non-polar molecules
• Symmetrical


  Balanced in shape
• Bond polarities do not cancel each other out in water
• Water is a polar molecule
• Dipole


  Charge poles
• Linear shape


  Shape of a molecule where the atoms/groups of atoms are arranged in a straight line
• Intermolecular forces

  Forces between molecules
• Water has 2 polar bonds but it is not linear
• Polar molecules

  • Water
  • Ammonia
  • Hydrogen fluoride
• Non-polar molecule


  Molecule with no overall charge
• To determine if a molecule is polar, check for symmetry. If the molecule is symmetrical, it will NOT be polar
• A molecule is polar IF it has polar bonds OR if it has any unshared pairs on the central atom
• Periodic table elements

  • H
  • J
  • Be
  • Mg
  • Ca
  • Ce
  • Th
  • C
  • Pa
  • U
  • Np
  • Pu
  • Am
  • Cm
  • Bk
  • and gyepinde
  • B
  • Al
  • Si
  • P
  • Cr
  • Mn
  • Fe
  • Co
  • Ni
  • Cu
  • Zn
  • Ga
  • Ge
  • As
  • Se
  • Br
  • In
  • Sn
  • Sb
  • Te
  • Xe
  • Mo
  • Tc
  • Ru
  • Rh
  • Pd
  • Ag
  • Cd
  • Hf
  • Ba
  • La
  • W
  • Re
  • Os
  • Pt
  • Au
  • Hg
  • At
  • Rn
  • Tl
  • Pb
  • Po
  • Bi
  • Ra
  • Ac
  • Rf
  • Db
  • Sg
  • Bh
  • Hs
  • Mt
  • Ds
  • Rg
  • Cn
  • Uut
  • Uuq
  • Uup
  • Uus
  • Uuo
• A polar bond is a covalent bond between two atoms where one atom has a greater electronegativity than the other
• Polar


  A molecule that has an uneven distribution of charge
• If the molecule is not completely symmetrical, it will be polar IF it has polar bonds
• A polar bond has a partial negative charge on the more electronegative atom and a partial positive charge on the less electronegative atom
• SNAP

  Symmetrical = Non-polar

  Asymmetrical = Polar