Question

Ccording to valence bond theory, which orbitals on N and H overlap in the NH3 molecule?

A) 2p on N overlaps with 2s on H
B) 2s on N overlaps with 1s on H
C) 2p³ on N overlaps with 2s on H
D) sp³ on N overlaps with 1s on H
E) 2p on N overlaps with 1s on H

Answer 1

In NH3, the sp³ hybrid orbitals of nitrogen overlap with the 1s orbitals of hydrogen to form covalent bonds. The correct answer is D) sp³ on N overlaps with 1s on H.

Step-by-step explanation:

The student asked about Valence Bond Theory and which orbitals overlap in the NH3 (ammonia) molecule. According to this theory, the nitrogen atom (N) in ammonia has a valence electron configuration of 2s²2p³, which can hybridize to form sp³ hybrid orbitals.

This hybridization results in four sp³ orbitals, where three of these are singly occupied and are available for bonding, and one sp³ orbital accommodates a lone pair of electrons. Hence, the orbitals that overlap to form bonds in NH3 are the sp³ hybrid orbitals of nitrogen with the 1s orbitals of hydrogen (H). The lone pair resides in the non-bonding sp³ orbital of nitrogen. Consequently, the correct answer to the question is:

D) sp³ on N overlaps with 1s on H

This type of bonding, where sp³ and s orbitals overlap, is referred to as sp³-s bonding. This model leads to a molecular geometry that approximates a tetrahedral shape, explaining why NH3 has a trigonal pyramidal geometry due to one of the sp³ orbitals containing a lone pair.