Question

Which of the following best describe the diagram of a molecular orbital?

A.A bonding \[\pi \] orbital
B.A non-bonding orbital
C.An antibonding \[\sigma \] orbital
D.An antibonding \[\pi \] orbitals

Answer 1

Hint:For this we must know the concept bonding of orbitals and shapes of orbitals. P orbital’s forms \[\pi \] bonds along sidewise interaction and in opposite phase constructive interference occurs.

Complete step by step answer:
There are different shapes of different orbitals. s orbital has spherical shapes and p orbital has two lobes and is termed as dumbbell shape and d orbital has double dumbbell shape and so on.
In the given figure we have been given two p orbital bonds to each other. As we can see each orbital has two lobes. They are overlapping with each other and show the formation of covalent bonds.
The formation of bonds in a chemical compound or bond also depends on in which phase the orbitals are combining. The plus and minus signs on the lobe does not indicate the charge but represents the phase. The physical significance of phase comes in existence when the orbital interacts. If the two orbits combine in the same phase then the electron density increases and constructive interference occurs. But if the orbitals combine in different phases than the net electron density decreases and destructive interference occurs. When constructive interference occurs the bonding molecular orbitals are formed and when they do destructive interference then antibonding molecular orbital forms.
Also p orbital can form either sigma bond or pi bond. If it interacts linearly i.e. only one lobe interaction is there then sigma bond forms and when sideways or lateral interaction occurs i.e. both the lobes interact then pi bond forms.
Since from the above diagram we can see that both the lobes are interacting, it means a \[\pi \] bond must have been formed. And since a positive lobe of one p orbital interacts with a negative lobe of another p orbital, an antibonding orbital must have been formed.

Hence option D is correct.

Note:
According to MOT, molecular orbital theory, whenever two orbital of nearly same energy mixes then two new orbital forms one with the lower energy which is called BMO, bonding molecular orbital and one with higher energy termed as ABMO, antibonding molecular orbital. This concept is completely opposite of hybridization in which orbitals of different energy mixes to produce orbitals of nearly the same energy.