Problem: Which of the following elements has the largest second ionization energy (IE2)?A. LiB. BC. OD. FE. Na

Ionization energy (I. E.) is the energy required to remove an electron from a gaseous atom or ion.

• First I.E. corresponds to removing the first valence electron from a neutral atom

• Second I.E. refers to removing a second electron

• Third I.E. refers to removing the third electron

First ionization energy → removing the first valence electron

Li → 1s²2s¹
B → 1s²2s²2p¹
O → 1s²2s²2p⁴
F → 1s²2s²2p⁵
Na → 1s²2s²2p⁶3s¹      

Second ionization energy → removing the second electron from X⁺ ion