Question

Which of the following will have the lowest electron affinity?

• A. Carbon
• B. Boron
• C. Sulfur
• D. Nitrogen

Answer 1

The correct option is D

Nitrogen

Explanation for correct option:

D. Nitrogen

Electron affinity:

• “The amount of energy released when an electron is added to a neutral atom to form a negatively charged ion, is called electron affinity."
• The electron affinity increases on moving across the period as there is an increase in effective nuclear charge, which more readily pulls these new electrons in.
• Going down the group the electron affinity should decrease since the electron is added to the shell.

As per the trend, electron affinity increases along the period so carbon would have lower electron affinity among carbon, nitrogen, and oxygen as all these three elements are present in the same period.

However, even though Nitrogen is present in Group-$15$ it has lower electron affinity than Carbon which is present in Group-$16$ as the extra stability of the half-filled $\text{2}{\text{p}}^{\text{3}}$ orbital of nitrogen.

Explanation for incorrect options:

The decreasing order of electron affinity of given elements is:
Sulphur > Boron > Carbon > Nitrogen

Hence, the correct option is D i.e. Nitrogen.