Question

The element with the highest first ionization potential is:

• A. boron
• B. carbon
• C. nitrogen
• D. oxygen

Answer 1

Answer: (C)

The first ionisation increases from left to right in a period. But nitrogen has greater ionisation energy than oxygen. The reason is that the electronic configuration of nitrogen $(1s^{2}2s^{2}2p^3)$ is stabler than that of oxygen. Hence, nitrogen requires more energy to loose an electron then oxygen.