Question

The first ionisation enthalpy of magnesium is higher than that of sodium. On the
other hand, the second ionisation enthalpy of sodium is very much higher than that of
magnesium. Explain. Plz answer correctly

Answer 1

Sodium has a smaller atomic radius, higher nuclear charge and has less shielding therefore the outer electron is more strongly attracted to the nucleus and because of that it requires more energy to remove the outer electron from a Mg atom than a Na atom,whereas second ionisation enthalpy of sodium is very much higher than that of magnesium because sodium has a valency of +1 which means it has to lose one electron to get a noble configuration i.e Neon's configuration.

So after it loses one electron it becomes stable and hence more enthalpy is required to remove an electron from the stable atom hence the second ionisation enthalpy of sodium is greater than that of Magnesium.

Hope this helps.