Why are the first ionization energies of some of the group 16 elements smaller than the first ionization energies of the nearby group 15 elements in the same period?
A. There is a decrease in effective nuclear charge and an increase in shielding across a row, so there is a decrease in the attraction between the nucleus and the surrounding electrons.
B. There is an enhanced stability in a half-filled set of d orbitals.
C. There is an enhanced stability in a half-filled set of p orbitals.
D. There is an increase in effective nuclear charge and a decrease in shielding across a row, so there is an increase in the attraction between the nucleus and the surrounding electrons.
The Correct Answer is (C) There is an enhanced stability in half-set of p orbitals.
The general electronic configuration of group 15 elements is.gif)
and that of group 16 elements.gif)
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and that of group 16 elements.gif){kind=small}
.The group 15 elements have exactly half-filled p orbitals and hence are highly stable, while group 16 elements are neither half-filled nor fully filled. Therefore, it is difficult to remove an electron from group 15 elements than group 16 elements.