Question

Na has a lower IE1 than Mg, but Mg has a lower IE2 than Na because: The radius of Na is smaller than that of Mg. IE1 increases from left to right across a period and IE2 decreases from left to right across a period. The radius of Mg is larger than that of Na. IE1 decreases from left to right across a period and IE2 increases from left to right across a period. IE1 increases from left to right across a period. However, because Na has only one valence electron, IE2 for Na involves the removal of a core electron − requiring significantly more energy.

Answer 1

Explanation: IE1 increases from left to right across a period. However, since Na has only one valence electron, IE2 for Na involves the removal of a core electron − requiring significantly more energy.