Q.46:- Define the term ionization enthalpy? How does it vary along a period and along a group?
Ionization Enthalpy. The minimum amount of energy required to remove the most loosely bound electron from an isolated gaseous atom so as to convert it into a gaseous cation is called its ionization enthalpy or energy. It is represented by A; H.
This process may be represented as M (g) + ∆iH -> M+ (g) + e–(g)
where M (g) is isolated gaseous atom.
M+ (g) is the resultant cation (a position ion)
Variation along a period. Moving from left to right in a period, the ionization enthalpy increases with atomic number.
Variation within a group. The ionization enthalpies keep on decreasing regularly as we move down a group from one element to the other.