Question

Define the second ionization energy. Which group of elements would have the maximum magnitude of this periodic property? Explain.

Answer 1

The second ionization energy is the amount of energy required to remove an electron from a $+1$ cation.

The $1^{\mathrm{st}}$ group will have the maximum second ionization energy.

Reasons:

• The valence electrons of first group elements $=1$
• After the first ionization or after the removal of one electron, the elements will attain a stable noble gas electronic configuration.

Eg: Sodium (Na)

• Atomic number $=11$
• Group number $=1$
• Electrons per shell $=2,8,1$
• Electrons per shell after $1^{\mathrm{st}}$ ionization $=2,8$ ( electronic configuration of Neon).

After attaining the stable noble gas electronic configuration, the removal of electrons will require an extreme amount of energy which is not feasible.

So, the magnitude of the $2^{\mathrm{nd}}$ ionization energy of the $1^{\mathrm{st}}$ group elements is the maximum.