Sum of bond order of CO and NO⁺ is ________.

Solution

Chemistry ma’am · 3 steps

Count the electrons first: CO and NO⁺ both have 14, the same as N₂, so each has bond order 3.

1. Count electrons. CO has 6 + 8 = 14 electrons. NO⁺ has 7 + 8 - 1 = 14 electrons, because the positive charge removes one. Both are isoelectronic with N₂.
2. Fill the MOs. Fourteen electrons fill σ 1s² σ^* 1s² σ 2s² σ^* 2s² π 2pₓ² π 2p_y² σ 2p_z². That puts 10 electrons in bonding orbitals and 4 in antibonding orbitals.

   B.O. = (N_b - Nₐ)/2 = (10 - 4)/2 = 3

3. So. Each species has bond order 3, so the sum is 3 + 3 = 6.

The common slip: 5.5. Forgetting the + charge and counting 15 electrons for NO⁺ gives bond order 2.5 (that is neutral NO), and a sum of 5.5.

The idea to keep. Isoelectronic species have the same MO filling and the same bond order. Any 14-electron diatomic, such as N₂, CO, NO⁺ or CN⁻, has bond order 3.

Answer from the NTA final answer key. Solution by PrepWiser.