Question

which element has the greater ionization energy?magnesium (mg)aluminum (al)iodine (i)phosphorus (p)

Explanation:

Step1: Recall ionization energy trend

Ionization energy generally increases across a period (left - to - right) and decreases down a group in the periodic table.

Step2: Analyze the positions of the elements

• Magnesium (\(Mg\)) and Aluminum (\(Al\)): \(Mg\) is in group 2 and \(Al\) is in group 13. In the third period, \(Mg\) has a higher ionization energy than \(Al\) because \(Mg\) has a filled \(3s\) sub - shell (\(1s^{2}2s^{2}2p^{6}3s^{2}\)) which is more stable. Removing an electron from \(Al\) (\(1s^{2}2s^{2}2p^{6}3s^{2}3p^{1}\)) is easier as it is removing a \(3p\) electron.
• Phosphorus (\(P\)) and Aluminum (\(Al\)): \(P\) is in group 15. In the third period, moving from \(Al\) to \(P\), ionization energy increases as we move right across the period.
• Phosphorus (\(P\)) and Iodine (\(I\)): \(P\) is in the third period and \(I\) is in the fifth period. Since ionization energy decreases down a group and \(P\) is above \(I\) (in different groups but considering the general trend of decrease down the group and increase across the period, and \(P\) is more to the right in its period compared to the position of \(I\) in its period in terms of ionization energy contribution).

Answer:

Phosphorus (\(P\))