[user11]

Hi, I have 2 questions and would really appreciate some help:

1) according to valence bond theory, do lone pairs always hybridize? So if an atom makes one bond and has 2 lone pairs would it then have 3 sp^2 orbitals?

2) why would dioxygen be predicted as diamagnetic according to Lewis theory? Is it because he would say that dioxygen contains 3 sp2 orbitals (one bond and 2 lone pairs for oxygen) so when the two o2 atoms bond all orbitals would be filled?

[user11]

Anyone?

[mjc123]

1. You can say so if you like. Hybridisation is a mathematical formalism, not a physical reality. VSEPR would say that electron pairs assume the geometry they do to minimise repulsion, without attributing it to hybridisation.
2. VB theory considers bonds in terms of sharing pairs of electrons. There is no reason within VB theory why an even-electron molecule such as O₂ should have unpaired electrons - it would have two electron-pair bonds and 2 lone pairs per O (isoelectronic with C₂H₄). The prediction of paramagnetism in O₂ constitutes a victory for MO theory in this case.