Question

Why does first ionization energy decrease from nitrogen to oxygen

Answer 1

bcz there is half filled (2p³) outermost subshell of N is highly stable and hence it becomes difficult to remove the electron. Thus, extra stability of half filled subshells is the cause of the irregularity.

Answer 2

Explanation:

ionization energy increases across a period and decreases down a group. Across a period, effective nuclear charge increases as electron shielding remains constant.

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