Question

Formation of anion from a neutral atom ${\text{X}}$ is favoured by:
A. high electron affinity
B. large size of ${\text{X}}$
C. low ionization potential
D. high charge on anion ${\text{X}}$

Answer 1

Hint: The change in the energy that occurs when there is a gain of electron by the neutral atom in gaseous phase which results in the release of energy is called electron affinity. Ionization energy/potential is the minimum energy required to remove the electrons that are loosely bound to the atom.

Complete step by step answer:
When the neutral atom accepts an electron it becomes an anion. During this process there occurs a change in energy which is given as electron affinity. The formation of anion results with high electron affinity, because with the addition of an electron to neutral atom there will be release of energy. Greater the amount of energy released, quicker will be the formation of anion.

So, the correct answer is Option A.

Additional information:
The factors affecting ionization potential are
Nuclear charge: With the increase in the nuclear charge, the nucleus holds the outermost electrons with greater attraction. Thus the energy required to remove the outermost electrons increases.
Ionization energy/potential is the minimum energy required to remove the electrons that are loosely bound to the atom.
Size of the atom: Smaller the atom, the electrons are more likely to be held with greater force of attraction thus distance of the outermost electrons from the nucleus also affects the ionization energy.
Shielding effect of the innermost electrons also has a great effect on ionization energy.
Factors affecting electron affinity are
With the increase in nuclear charge the incoming electrons attraction towards the nucleus also will be greater.
With the increase in the distance between the nucleus and incoming electron i.e., the increase in the size of the atom has an adverse effect on the electron affinity.

Note: If a neutral atom loses an electron then it results in the formation of cation and if there is an addition of electron then it forms anion. The size of the neutral atom decreases along the period and increases down the group.