among the elements of the main group, the general trend in the first ionization energy moving across a…

among the elements of the main group, the general trend in the first ionization energy moving across a period is not followed between group 2 and group 13. which best explains these exceptions? o the ionization energy decreases because the full s orbital shields the electron entering the p orbital. o the ionization energy increases because the full s orbital shields the electron entering the p orbital. o the ionization energy decreases because the stability of the half - full p subshell is increased. o the ionization energy increases because the stability of the half - full p subshell is increased.

among the elements of the main group, the general trend in the first ionization energy moving across a period is not followed between group 2 and group 13. which best explains these exceptions? o the ionization energy decreases because the full s orbital shields the electron entering the p orbital. o the ionization energy increases because the full s orbital shields the electron entering the p orbital. o the ionization energy decreases because the stability of the half - full p subshell is increased. o the ionization energy increases because the stability of the half - full p subshell is increased.

Answer

Brief Explanations:

In main - group elements, when moving from group 2 to group 13 across a period, the first ionization energy decreases. Group 2 has a full s - orbital ($ns^{2}$) and group 13 has an electron in the p - orbital ($ns^{2}np^{1}$). The full s - orbital shields the electron in the p - orbital, making it easier to remove the p - electron, thus decreasing the ionization energy.

Answer:

The ionization energy decreases because the full s orbital shields the electron entering the p orbital.