Question

According to molecular orbital theory,
which will not be a viable
molecule ?
Plz don't use google

Answer 1

H2^2^- is the answer

Answer 2

Hello dear,
This question doesn't make sense without options. Don't worry. I'll add those.

# Options should be -
(1) (He2)+
(2) (H2)-
(3) (H2)2-
(4) ​(He2)2+


● Answer -
(3) (H2)2-

● Explanation -
(1) (He2)+ => σ1s2 σ*1s1
Bond order = (Nb-Na)/2
Bond order = (2-1)/2
Bond order = 0.5
∴ (He2)+ is viable due to non-zero bond order.

(2) (H2)- => σ1s2 σ*1s1
Bond order = (Nb-Na)/2
Bond order = (2-1)/2
Bond order = 0.5
∴ (H2)- is viable due to non-zero bond order.

(3) (H2)2- => σ1s2 σ*1s2
Bond order = (Nb-Na)/2
Bond order = (2-2)/2
Bond order = 0
∴ (H2)2- is non-viable due to zero bond order.

(4) (He2)2+ => σ1s2
Bond order = (Nb-Na)/2
Bond order = (2-0)/2
Bond order = 1
∴ (He2)2+ is viable due to non-zero bond order.

Hope this helped you...