Question

The first ionization energy of nitrogen is higher than that of oxygen or carbon. Explain.

Answer 1

Following are the electronic configurations of two elements:

N: 1s2, 2s2, 2p3

O: 1s2, 2s2, 2p4

As we can see that Nitrogen has half filled p orbitals which is relatively stable configuration as compared to 2p4 configuration of Oxygen atom so it is difficult to remove one electron from this stable configuration. Further, removal of one electron from Oxygen atom is relatively easy because it results in half filled stable p orbital configuration. That's why ionisation energy of Nitrogen is more than Oxygen.

Answer 2

Answer: This is so because nitrogen has half filled electronic configuration.

Explanation:

Ionization energy is defined as the energy required to remove an electron from an isolated gaseous atom. It is represented as $E_i$

This energy will be higher for fully filled and half-filled electronic configuration than partially filled electronic configuration. This is so because half filled and fully filled configurations are stable.

Nitrogen is the 7th element of the periodic table having electronic configuration of = $1s^22s^22p^3$

This element has half filled 'p'-orbital. Thus, first ionization potential will be higher.

Oxygen is the 8th element of the periodic table having electronic configuration of $1s^22s^22p^4$

This element has partially filled 'p'-orbital. Thus, first ionization potential will be lower.

Carbon is the 6th element of the periodic table having electronic configuration of $1s^22s^22p^2$

This element has partially filled 'p'-orbital. Thus, first ionization potential will be lower.

Hence, this is so because nitrogen has half filled electronic configuration.