Answer to Question #160457 in General Chemistry for John

Question

 Plot a graph of first ionisation energy against atomic number for the elements Li → Ar.

Explain the trends observed in the above graph for the period 3 elements Na →Ar.

Answer 1

In general, the ionization energy increases over the period due to an increase in the nuclear charge. But two leaps are observed: for magnesium and for phosphorus. This is due to the fact that these elements have completely filled sublevels magnesium - s, phosphorus - p

, which is a very stable state.