Question

Explain the various factors that affect electron affinity?

Answer 1

We have to remember that in the world all the material is made up of atoms. These are binding between one element to another through bond. These bond formation depends on the electronegativity and ionisation energy. In periodic table trends it is easy to understand the nature of elements. In a periodic table having rows and columns comes in groups and periods. In same period and same row element trend in electron affinity.

Complete step by step answer:
We must know that in the ground state, an isolated gaseous atom from its anion by an electron is added to the outermost shell to release some amount of energy. This energy is known as electron affinity. The charge of the electron is negative.
$A + 1{e^ - } \to {A^ - } + {E_A}$
Now we discuss about the factors affect the electron affinity as,
Atomic size of the atom: We have to remember that the size of the atom is inversely proportional to the electron affinity. The atomic size is increased, electron affinity of the atom decreases and atomic size decreases electron affinity of the atom increases.
We must know that the number of the energy level is inversely proportional to the electron affinity. The number of energy levels increases electron affinity decreases in the same group of the element. The number of energy levels decreases as electron affinity of the atom increases.
We need to remember that if the charge of an atom increases which leads to increase the attraction towards incoming electrons. Thus the value of electron affinity also increases.
As we know that the atom has a ful filled electronic configuration which has less capacity to receive electrons. Thus causes smaller change in the electron affinity values.
We also have to know that the shielding effect is inversely proportional to electron affinity. Shielding effect increases as the electron decreases. Shielding effect decreases as electron affinity increases. The electron in the outermost shell of an atom shields the attractive force from the nucleus to the coming electron. The shielding effect also affects the electron affinity of the atom. The number of electrons in the outermost shell increases, its negative charge increases and it repels the coming electron. So, the electron affinity of the atom decreases.
Partial filled atoms have greater electron affinity than completely and half-filled atoms. Because, completely and half-filled atoms accept the electron it loses its stability.
These are factors that affect the electron affinity of the atom.

Note:
We must know that the electron affinity is used to form atoms to anion. The formation of these anions is used to make an ionic bond. In periodic table, move from left to right electron affinity of the elements increases and move from top to bottom electron affinity decreases. In this away to remain the electron affinity trends.