Bonding pairs to electronegative substituents occupy less space than those to more electropositive substituents. 2- SO 2 SF 4 Electron density contour plot of SF 4 . Electrostatic potential map for SF 4 . Note the axial F atoms are more electron rich than the equatorial ones. The formation of the valence state costs 406 kJ. The C valence state suggests that the angles will be 90 o instead of the observed 109.5 o .
Different hybridizations allow different geometries.
Trends in Bond Energies Main Group Elements Bond energies tend to decrease as one descends a group. F 2 is very reactive. There is better orbital overlap for p -bonding for 1 st row elements. Compare N 4 vs P 4 . Thus there is better orbital overlap.