Question

What is the number of sigma bond in P4O10. I have got 16 as well as 13 which one is correct?? Please explain

Answer 1

Structure of P₄O₁₀ is in image attached.
It has 13 σ-bonds and 3 π-bonds

Answer 2

$P_4O_{10}$ contains 16 σ-bonds and 4 π-bonds. Therefore, the effective number of σ-bonds is 16 and not 13.

Explanation:

In $P_4O_{10}$ each P atom is surrounded by 4 oxygen atoms. One of the bonds of P with O is a double bond.

Therefore, for every P atom, we have 1 π-bonds and 4 sigma bonds. Likewise, we have 4 P atoms in total.

Therefore, the total number of sigma bonds will be 4 $\times$ 4 which is 16 and total number of pi bond will be 4 $\times$ 1 which is 4