Question

Two atoms have the electron configurations 1s2 2s2 sp6 and 1s2 2s2 2p6 3s1. The first ionization energy of one is 2080 kJ/mol and that of the other is 496 kJ/mol Match each ionization energy with one of the given electron configurations. Justify your choice.
The answer is 1s2 2s2 2p6: 2080 k/mol

I can't figure out how to get this answer. Please help!! :(

Answer 1

look
p has 3 orbitals which can accomodate a max of 6 electrons .
Hence when you have a fully filled outer shell (here 2p6) the molecule tends to become much more stable and it is difficult to remove electrons from a stable configuration...
so a higher energy has to be given to the system to remove the electron, hence its higher I.E. value.
the other one having half-filled configuration, needs less energy to remove an electron from the outer most shell, hence a comparatively lower I.E.