Nitrogen's electron affinity is around zero because of which condition?

Nitrogen's electron affinity is around zero because of which condition?

• A. It has a fully filled valence shell.
• B. It has a noble gas electron configuration.
• C. It has a half-filled 2p subshell.
• D. It has a low nuclear charge.

Answer: (C)

Electron affinity measures the energy change when an atom in the gas phase gains an extra electron. For nitrogen, the 2p subshell is half-filled: each of the three p orbitals contains one electron with its own spin. This arrangement is relatively stable due to exchange interactions and minimizes repulsion. Adding another electron would force pairing in one of the p orbitals, which increases repulsion and reduces the stabilizing exchange energy. As a result, gaining an electron does not release much energy, so the electron affinity sits near zero. This is why the condition of having a half-filled 2p subshell best explains nitrogen’s near-zero electron affinity.

Electron affinity measures the energy change when an atom in the gas phase gains an extra electron. For nitrogen, the 2p subshell is half-filled: each of the three p orbitals contains one electron with its own spin. This arrangement is relatively stable due to exchange interactions and minimizes repulsion. Adding another electron would force pairing in one of the p orbitals, which increases repulsion and reduces the stabilizing exchange energy. As a result, gaining an electron does not release much energy, so the electron affinity sits near zero. This is why the condition of having a half-filled 2p subshell best explains nitrogen’s near-zero electron affinity.