Question

Why electron gain enthalpy of magnesium is positive?

Answer 1

Que. Why electron gain enthalpy of magnesium is positive?

Electron gain enthalpies of Be and Mg are positive because of the following reasons: ... They have fully filled s orbitals and addition of new electron would move to the higher energy p . 3. This addition of new electron is very energetically unfavorable and so this accounts for the more positive electron affinity.

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Answer 2

Electron gain enthalpies of beryllium and magnesium are also positive. This is attributed to the extra stability of the fully completed s-orbitals in Be(2s2), Mg (3s2). The gain of electron is highly endothermic. Thus, if an atom has fully filled orbitals, its electron gain enthalpy value will be positive