Question

Write applications of electronegativity and electron gain enthalpy.

Answer 1

Electronegativity, which was initially defined by Pauling in 1932 as “the power of an atom in a molecule to attract electrons to itself,” is one of the most important concepts in chemistry, physics, and materials science..

Application of electronegativity:

1. Nature of bond : The concept of electronegativity can be used to predict whether the bond between similar or dissimilar atoms is non-polar covalent bond, polar covalent bond (or) ionic bond.
(a) When χ_A = χ_B i.e. χ_A – χ_B = 0, then A-B bond is non-polar covalent bond or simply covalent bond and is represented as A-B.
(b) When χ_A is slightly greater than χ_B, i.e. X_A - X_B is small, the A-B bond is polar covalent bond and is represented as A^δ- – B^δ+.
(c) When χ_A > χ_B, i.e., X_A - X_B is very large, A-B bond is more ionic or polar bond and is represented as A – B, Since χ_A >> χ_B.

2. Percentage of ionic character in a polar covalent bond : It χ_A – χ_A > 1.7 then covalent character is less then 50%. while ionic character more than 50%.
1. When (x_A – x_a) = 1.7 then bond is 50% ionic and 50% covalent.
2. When (x_A – x_B) < 1.7 then covalent character is more than 50%. While ionic character is less then 50%.

Application of electron gain enthalpy:

(i) Nature of Bonds : If the difference between ionization enthalpy and electron gain enthalpy of two elements is less than lattice energy, then they form ionic bond. Whereas if the difference is more than lattice energy, the bond formed will be covalent.

(ii) Reactivity of Elements : The elements whose electron gain enthalpy is high are generally more reactive. In a period, halogens have highest electron gain enthalpy and are highly reactive.

(iii) Oxidising Tendency : As the value of electron gain enthalpy increases, oxidising tendency increases.