Final answer:
Oxygen differs from the other elements in Group 16 in its oxyanion structure, ionization energy due to Hund's rule, and its role as a strong oxidizing agent.
Step-by-step explanation:
Oxygen differs from the outer elements in Group 16 in several notable ways. To start with, oxygen has a unique characteristic when it comes to the formation of oxyanions. While carbon and nitrogen from the second row form oxyanions with three oxygen atoms, and phosphorus and sulfur from the third row form oxyanions with four oxygen atoms, oxygen, although in Group 16, does not follow this trend due to its position and different electron configurations.
Moreover, the ionization energies in Group 16 decrease as we go down the group, with oxygen having a higher ionization energy than sulfur. This is explained by Hund's rule: oxygen has four electrons in the 2p sublevel with one pair of electrons, making it easier to remove a paired electron compared to an unpaired electron in elements like nitrogen from Group 15.
Lastly, oxygen's high electronegativity makes it one of the strongest oxidizing agents in its group, capable of oxidizing elements below it in the periodic table. Its reactivity and the nature of its bonds, often forming double bonds as seen in O2 compared to single bonds in heavier Group 16 elements, underscore its distinct behavior.