JEE AdvancedHardQuestion 840010
Question
The second ionisation energy of Na is very large compared to its first because:
- AThe second electron is removed from a filled 2p⁶ configuration (noble gas core)Correct
- BNa is a small atom
- CNa²⁺ doesn't exist
- DNuclear charge drops after 1st IE
Correct answer
The second electron is removed from a filled 2p⁶ configuration (noble gas core)
Explanation
Na: 1s²2s²2p⁶3s¹. IE₁ removes the lone 3s electron (relatively easy). IE₂ removes an electron from the filled 2p⁶ noble-gas-core configuration — extremely stable → requires enormous energy. IE₂/IE₁ ratio ≈ 9 for Na.