Ionization energy

Question

Arrange the following species in order of decreasing first ionization energy:

Ar

Ca

Xe

Ne

Answer 1

Ionization energy decreases as you go from right to left across a period and from top to bottom in a group.

Amongst the 4 elements, 3 of them (Ar, Xe, Ne) are noble gases while Ca is the only metal.

Since Ca is on the left side of the periodic table, it will have the lowest ionization energy than the 3 noble gases.

Between the 3 noble gases, Ne will have the highest I.E. whereas Xe will have the lowest.

The final order is:

Ne > Ar > Xe > Ca