The electron affinity value are negative for : A. \(\mathrm{Be} \rightarrow \mathrm{Be}^{-}\) B. \(\mathrm{N} \rightarrow \mathrm{N}^{-}\) C. \(\mathrm{O} \rightarrow \mathrm{O}^{2-}\) D. \(\mathrm{Na} \rightarrow \mathrm{Na}^{-}\) E. \(\mathrm{Al} \rightarrow \mathrm{Al}^{-}\) Choose the most appropriate answer from the options given below :

JEE Main · 2024 · 06 Apr 2024 · Shift 1 · Classification of Elements and Periodicity

The electron affinity value are negative for :
A.

Be \to Be^{-}

N \to N^{-}

O \to O^{2 -}

Na \to Na^{-}

Al \to Al^{-}

Choose the most appropriate answer from the options given below :

(A)D and E only✓ Correct
(B)A, B, D and E only
(C)A and D only
(D)A, B and C only

Answer: (A)

Solution

Electron gain enthalpy is negative when energy is released as a species accepts an electron. Adding an electron to beryllium, which already has a stable filled

2 s^{2}

subshell, is endothermic, so its value is positive. Nitrogen has a stable half-filled

2 p^{3}

configuration and resists the incoming electron, again making the process endothermic. Forming

O^{2 -}

requires forcing a second electron onto an already negative

O^{-}

ion, which demands a large energy input and is strongly endothermic. For sodium and aluminium, however, the added electron enters a neutral atom and energy is released, so these processes have negative electron gain enthalpy values. Only the sodium and aluminium processes are negative.

JEE Main · 2024 · 06 Apr 2024 · Shift 1 · Single correct option

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JEE Main · 2024 · 06 Apr 2024 · Shift 1 · Classification of Elements and Periodicity

Solution

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