5.1.2: Molecular Orbitals from p Orbitals

• There are three possible atomic orbitals in the 2p level where electrons can be found: px, py, and pz
• Orbital interactions are governed by symmetry
• When orbitals mix, one combination goes up in energy and one goes down in energy
• The s and p levels remain separate from each other
• The combination of one s orbital with another s orbital will rearrange to produce two new orbitals
• The bonding combination which the orbitals are in phase produces a new orbital with a longer wavelength and a lower energy than the original orbital
• The antibonding combination which the orbitals are out of phase produces a new orbital with a shorter wavelength and higher energy than the original orbital
• p orbitals are directional in that they lie along a particular axis
• in-phase combination results in constructive interference
• out-of-phase combination results in destructive interference
• p orbitals can approach each other side by side, above and below the bond axis between the two atoms
• parallel p orbitals can overlap to produce bonding and antibonding combinations which the resulting orbitals contain nodes along the bond axis (pi bond)
• in a main group diatomic species, one p orbital lying along the bond axis can engage in s bonding
• two p orbitals orthogonal to the bond axis can engage in p bonding
• higher-energy orbitals contain more nodes
• a p orbital is not symmetric with respect to the bond axis
• an s orbital is not affected when the atom at one end of the bond is rotated with respect to the other, the p orbital would have to stretch to maintain the connection