# What is the molecular electron configuration of #"F"_2#?

##### 1 Answer

#(sigma_(2s))^2 (sigma_(2s)^"*")^2 (sigma_(2p_z))^2 (pi_(2p_x))^2 (pi_(2p_y))^2 (pi_(2p_x)^"*")^2 (pi_(2p_y)^"*")^2#

Recall that there are orbital mixing effects for homonuclear diatomic molecules that decrease from left to right until

Notice how the

#sigma_(g)(2p)# , or the#sigma_(2p_z)# molecular orbital, dips down below the#pi# molecular orbital energies after#"N"_2# .

Since

In general, the molecular orbital energies follow these rules:

- The
*relative*atomic orbital energy differences approximate the*relative*#sigma//sigma# orbital energy differences.

So,

#sigma_(2s)# molecular orbitals are significantlylowerin energy than#sigma_(2p_z)# molecular orbitals because the corresponding#2s# atomic orbitals are significantly lower in energy than the#2p# 's.

#sigma# molecular orbitals are**singly**-degenerate, and#pi# molecular orbitals are**doubly**-degenerate.#sigma# molecular orbitals, in principle, get more stabilized upon overlap than#pi# molecular orbitals do.

For example, an

and an

So, the **full MO diagram** is:

Thus, the valence electron configuration is:

#color(blue)((sigma_(2s))^2 (sigma_(2s)^"*")^2 (sigma_(2p_z))^2 (pi_(2p_x))^2 (pi_(2p_y))^2 (pi_(2p_x)^"*")^2 (pi_(2p_y)^"*")^2)#