Question

First, second, third and fourth ionization enthalpies of an element are $579, 1795, 2758\, and\, 11580$ $kJ/mol$ respectively, then stable state of element is:
(A) +1
(B) +2
(C) +3
(D) +4

Answer 1

Ionization enthalpy is defined as the enthalpy change which is associated with the removal of the first electron from the isolated gaseous atom in its ground state. It is energy which is required so that the electron can be removed from the isolated gaseous atom. The ionization enthalpy increases along the period and it decreases down the group.

Complete step-by-step answer: As the atomic radius decreases along the period so the size of the atom also decreases as the attractive force which is present between the nucleus and the outermost electron in the period and closeness between the valence electron and nucleus increases due to which the ionization energy increases along the period. Whereas down the group the atomic number of the elements and also the number of shells down the group increases. The outermost electron or the valence electron becomes far from the nucleus and can be removed easily now. The shielding effect which is present in the atom orbital also decreases due to the increase in the shells so the ionization energy decreases down the group.
On observing the differences present between the ionization enthalpies of the element given we can see that the ionization value for the difference between third and fourth is too high. This means that the energy which is required to remove the electron for further ionization is much. This means that the $4th$ ionization of the element will be difficult. That means the element is the most stable at its oxidation state of $+3$.

So the correct answer is option (C).

Note: The ionization enthalpy depends on the three factors and they are penetration effect, electronic configuration and shielding effect. The meaning of word penetration is the proximity of the electron in the orbital to the nucleus. Shielding effect means the effect in which the inner electrons present which develop the shield for electrons which are present in outer shells and do not let appropriate nuclear charge towards them.