Question

How to answer question?

which of theses atoms can be Hypervalent and explain why?
fluorine, oxygen, carbon, selenium?

Answer 1

All of them

Explanation:

Fluorine normally is -1 but can form up to 7 bonds with its seven valance electrons.

Oxygen is normally -2 but can form up to six bonds with its six valance electron. ( particularly when bonded to Fluorine.)

Carbon typically is + 4 (`CO_2`)but can be -4, when bonded to Hydrogen (`CH_4`)or other atoms that have a lower electronegativity Carbon can also be + 2 ( CO) or -2
The differences are wether Carbon hybridizes is four valance electrons giving it four bonding electrons, or doesn't hybridize leaving Carbon with only 2 p orbital electrons that can bond.

Selenium `34` is in the same family as Oxygen. Therefore Selenium can form a -2 charge like Oxygen. However because Selenium has a much lower negativity than Oxygen it more commonly forms a +2, +4 or +6 charge.