Question

1. Describe below (briefly) a) the motivation for hybridization in valence bond theory and b) why valence bond theory cannot predict magnetism. In your answer, make sure to include a description of how molecular orbital theory addresses magnetism.

Answer 1

(I) Hybridization is the idea that atomic orbitals fuse to form newly hybridized orbitals.

It means , it is defined as the concept of mixing two atomic orbitals with same energy

level to give a degenerate new type of orbitals.

The hybridization is necessary in valence bond theory , this is due to the reason that

valence bond theory explains the chemical bonding beween two atoms according to

this the bonding is caused by overlap of half filled atomic orbital , the two atoms share each other's

unpaired electron to form filled orbital to form hybrid orbital and bond

(II) Valence bond theory cannot predict magnetism.

Paramagnetism is a form of magnetism whereby certain materials are attracted by an

an externally applied magnetic field. Valence bond theory does not do a good job at

predicting whether a molecule is paramagnetic or diamagnetic since it is not attracted by an external magnetic field

Where as MO Theory predict wheather the molecule is paramagnetic or diamagnetic , if electrons are paired the molecule is diamagnetic , if electron are unpaired the molecule is paramagnetic.