IMAT 2018 - Ionisation energy

Hi! Could someone explain why B is the answer instead of C. I picked C because it has the least amount of electrons but with a higher atomic mass which would give a higher attraction between the valence electron in the nucleus giving a higher ionisation energy

Thanks in advance!


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The answer is B because element W is Neon (noble gas). Those have the highest ionisation energy because its extremely difficult to “steal” an electron away from them:)

Also, I understand your reasoning if we were to choose between C or E, but a higher atomic mass doesnt necessarily indicate more protons - could be more neutrons too. Therefore, the force of attraction between the electrons and nucleus doesnt have to be higher in B compared to E.

Hope it makes sense:)


Oh yess it could be more neutrons haha, thanks for correcting me, it’s probably because when it has a FULL outer shell, it’s much harder to remove it from the shell. Thank you so much:))