NEETChemistryChemical Bonding and Molecular Structure
Assuming KK represents the closed inner shells (1s)^2 ^ * (1s)^2 , which of the following valence molecular orbital configurations corresponds to a species that does not exist?
Options
- AKK (2s)^2 ^ * (2s)^2
- BKK (2s)^2 ^ * (2s)^2 (2p_x)^2 = (2p_y)^2
- CKK (2s)^2 ^ * (2s)^2 (2p_x)^1 = (2p_y)^1
- DKK (2s)^2
Correct answer
A. KK (2s)^2 ^ * (2s)^2
Step-by-step solution
The existence of a molecule is determined by its bond order. A species does not exist if its bond order is zero or negative. Bond order = 1 2 (N_b - N_a) . The inner shell KK has N_b = 2 and N_a = 2 , so its net contribution to the bond order is zero. Let us calculate the bond order for each given configuration: 1) KK (2s)^2 ^ * (2s)^2 : Valence N_b = 2 , N_a = 2 . Total B.O. = 1 2 (2 - 2) = 0 . This represents Be ₂ , which does not exist. 2) KK (2s)^2 ^ * (2s)^2 (2p_x)^2 = (2p_y)^2 : Valence N_b = 6 , N_a = 2 . To