Question

Why formation of uni negative ion is exothermic while dinegative ion is endothermic?

Answer 1

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☆☞ Here is ur answer ☜☆

☆☞ A uni-negative atom, already has one excess electron in its valence shell, which is providing it its negetive charge, now when, another electron is added to the valence shell, it faces repulsion from this already present electron, and thus, some energy is required to add this electron which makes it energy/heat absorbing (endothermic).

☆☞ While a neutral atom, when adding another electron does not face any such repulsions (as its a neutral species), hence, it goes on to achieve noble gas configuration and thus releases energy, to become stable!

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Answer 2

Answer:

The formation of cations is called as endothermic and the formation of anions is called exothermic.

Explanation:

Endothermic Reaction:

Endothermic reactions are those that absorb chemical energy from their surroundings. For example, ice cubes melting and water evaporation.

Formation of di negative ion:

• When an electron is added to an uni negative ion, the extra electron offers an interelectronic repulsion to the incoming electron.
• Then the energy must be given to overcome this repulsion, resulting in an endothermic reaction.

Exothermic reactions

Exothermic reactions release energy into the environment as heat. For example burning sugar, combining water and a strong acid

Formation of uni negative ion:

• Because of the strong nuclear force given by the neutral atom's nucleus, the attraction between the nucleus and the newly added electron is very strong.
• Then the energy is released during the process of adding electrons to the neutral atom, resulting in an exothermic process.

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