Molecular orbital theory notes

Jul 25, 2022, 16:45 IST

Basic concepts of molecular orbital theory 

One of the most important theories developed regarding the wave-particle duality is the MOT.. Electrons can be considered as particles and waves also. Based on this, it can be concluded that electrons behaving as waves can interact with each other and the process is called interference.

As in waves, two types of interferences are possible: (1) constructive and (2) Destructive.

In molecules the atomic orbitals of all the atoms are assumed to interfere with each other in the form of waves and depending on the nature of interferences, two molecular orbitals result. The one which results from constructive interference is called bonding molecular orbital and the one which results from destructive interference is called anti-bonding molecular orbital. Obviously anti-bonding MO is of higher energy than bonding MO.

In denoting MO's,  sigma indicates head-on overlap of orbitals, pi represents side-ways overlap of orbitals.

represents anti-bonding orbital and its absence represents bonding MO. In simple homonuclear diatomic molecules the order of filling MO's based on increasing energy

Example of molecular orbital theory