A. Explain how molecular orbitals are formed?

B. Give the consequence from molecular orbital theory?

C. Use bond order to determine the possibility of bond formation in the following molecule:

A. Li2 B. Be2 C. He2 D. O2

Answers

A. Molecular orbitals are formed by combination of atomic orbital that have similar energy.

In molecular orbital atomic orbital of the first atom which have similar energy with ii atomic orbital combine together to form molecular orbital. For example 1s of the first atom can only combine with 1s of the second atom to form molecular orbital i.e 1s orbital is formed by combination of 1sa of the atom with 1sb of the second atom to give 1s molecular orbital

B. The consequence from molecular orbital theory are as follow:

1. Prediction whether a molecule exists or not : from the molecular orbital theory we can used bond order to calculate if diatomic molecule exist or not. On the calculation if the number of bond order is greater than zero then the molecule will exist but if the number of bond order calculated is lower than 0 then the molecular orbital will not exist.

for example helium bond order of 0.5 as such helium exist as an atom but the molecule is zero.

1. paramagnet property of oxygen molecule : successful prediction of electronic configuration of oxygen is one of the significant contribution molecular orbital theory made. The results from the experiments revealed that oxygen is paramagnetic and the two unpaired electron of oxygen have the same spin.