The total number of molecular orbitals formed from 2s and 2p atomic orbitals of a diatomic molecule

Core Logic

According to Molecular Orbital Theory (MOT), the number of molecular orbitals (MOs) formed is equal to the total number of atomic orbitals (AOs) combined.

Step 1: Counting atomic orbitals

For a single atom in the 2nd period, the valence shell has: One 2s orbital Three 2p orbitals (2pₓ, 2py, 2pz$2p_x, 2p_y, 2p_z$) Total = 4 atomic orbitals per atom. For a diatomic molecule, two such atoms combine. Total atomic orbitals = 4 × 2 = 8$4 \times 2 = 8$.

Step 2: Forming molecular orbitals

Combining these 8 atomic orbitals yields 8 molecular orbitals:

• From 2s: σ₂ₛ$\sigma_{2s}$ and σ^*₂ₛ$\sigma^*_{2s}$ (2 MOs)
• From 2p: σ2pz, π2pₓ, π2py, π^2pₓ, π^2py, σ^*2pz$\sigma_{2p_z}, \pi_{2p_x}, \pi_{2p_y}, \pi^_{2p_x}, \pi^_{2p_y}, \sigma^*_{2p_z}$ (6 MOs)

Total MOs = 2 + 6 = 8$2 + 6 = 8$.

Chapter Mix

Class 11 Chemistry: Chemical Bonding and Molecular Structure