Question

which of the following element have 2nd IP <1st IP 1)Mg 2)Ne 3)C 4) none.. Please explain the answer

Answer 1

Answer: 1) Mg

Explanation:

Ionization energy is defined as the energy required to remove an electron from an isolated gaseous atom.

This energy will be higher for fully filled and half-filled electronic configuration than partially filled electronic configuration. This is so because half filled and fully filled configurations are stable.

Mg: 12: $1s^22s^22p^63s^2$

1. Magnesium has fully filled s orbital and thus first ionization potential is higher .Thus, first ionization potential will be higher.

$Mg^+:11:1s^22s^22p^63s^1$

After loss of one electron, the second electron will be lost easily as it will acquire inert gas configuration after loss of second electron.

Thus 2nd IP < 1st IP for magnesium.

2. Ne: 10: $1s^22s^22p^6$

Neon has fully filled 'p'-orbital. Thus, first ionization potential is higher.

$Ne^+:9:1s^22s^22p^5$

3. C: $1s^22s^22p^2$

$C^+:1s^22s^22p^1$

Carbon has partially filled 'p'-orbital. Thus, first ionization potential will be lower.