bond polarity - measure of electron sharing

• overall dipole = sum of bond dipoles
  • dipoles have magnitude/direction
  • consider shape to find overall polarity
• nonpolar molecule - overall dipole moment of 0
  • bond dipoles cancel each other out
• polar molecule - nonzero overall dipole moment
  • when molecule not the same all around

valence-bond theory - explains covalent bonding

• orbitals overlap to form covalent bonds
• optimum distance between bonded nuclei
• bond length - distance where attractive forces (between electrons/nuclei) are balanced by repulsive forces (between electrons/electrons, nuclei/nuclei)

hybrid orbitals - new orbitals formed by a mix of other orbitals

• hybridization - process of mixing/changing atomic orbitals
• energy released by bond formation > energy needed to promote electrons to higher levels
• sp hybrid orbital - 1 electron from s subshell promoted to p subshell
  • able to form 2 bonds
  • forms linear arrangement
• sp2 hybrid orbital - 1 electron from s subshell promoted to p subshell
  • 1 electron in s subshell, 2 electrons in p subshell
  • forms trigonal planar arrangement
• sp3 hybrid orbital - 1 electron from s subhsell promoted to fill p subshell
  • forms tetrahedral arrangement
• hybridization w/ d orbitals - possible w/ atoms in 3 rd period and beyond
  • sp3d hybrid orbital - trigonal bipyramidal arrangement
  • sp3d2hybrid orbital - octahedron arrangement