Question

The ionization energy of magnesium is less than that of sodium and aluminium.

• A. True
• B. False

Answer 1

The correct option is B False

Ionization energy

ionization energy is the minimum energy that an electron in a gaseous atom or ion has to absorb to come out of the influence of the nucleus.

1. Atomic number of Sodium(Na) = 11 (1s²2s²2p⁶3s¹)
2. Atomic number of Magnesium(Mg) = 12 (1s²2s²2p⁶3s² )
3. Atomic number of Aluminium(Al) = 13 (1s²2s²2p⁶3s²3p¹ )
4. While writing the electronic configuration 3s is the highest energy orbital of both Mg and Na.
5. Mg's orbital is fully filled and Na's half-filled. Thus more energy will be required to remove the electron from the same orbital (3s), making the ionization energy of magnesium higher than that of sodium.
6. When the ionization energies of magnesium and aluminium are compared, magnesium has higher ionization energy because it has fewer shells that are closer to the nucleus.
7. In Al's highest energy orbital (3p), one electron is unpaired, whereas, in Mg's highest energy orbital (3s), the electrons are paired.

Hence the given statement is false.