Question

Rank these elements according to electron affinity. Most energy released by gaining an electron Most energy absorbed by gaining an electron Ga Br Kr

Answer 1

Explanation:

Electron affinity is the energy released when an electron is added to a neutral atom to form negative ion.

If the negative ion formed is stable then energy is given out. More is stability of negative ion more is the electron affinity. If the negative ion formed is unstable then energy is absorbed and less is the electron affinity.

Bromine atom forms Br^- ion upon accepting an electron. The Br^- ion formed is stable due to completion of octet of electron in outer shell. Therefore, larger amount of energy is released or Br has more electron affinity.

Ga atoms form Ga^- ion upon accepting an electron. The Ga^- ion is less stable than Br^- ion. Thus, energy released is less. Therefore electron affinity of Ga is less than that of Br.

Kr is inert gas and an atom of Kr will form Kr^- ion upon accepting an electron. Kr^- ion is very unstable and instead of releasing energy, energy is absorbed during conversion of Kr to Kr^-. Thus, Kr has lowest electron affinity.