Chapter 3 Question 51

[Katie Lam 1B]

Hypochlorous acid, HClO, is found in white blood cells,
where it helps to destroy bacteria. Write two Lewis structures
with different atom arrangements for HClO and select the most
likely structure by identifying the structure with formal charges
closest to zero. Consider only structures with single bonds.

One of the Lewis structures has oxygen as the central atom, and the other has chlorine as the central atom. When chlorine is the central atom, it has two single bonds, one with hydrogen and one with oxygen. But doesn't chlorine usually only share one bond? How does it bond twice?

[Chem_Mod]

It is a valid Lewis structure for Cl to be the central atom, but it is highly unlikely as there are separation of charges between Cl (+1) and O (-1). When Cl bonds twice, its formal charge becomes +1 because it only has 2 single bonds and 4 electrons from lone pairs (it is short of 1 electron from its neutral atom). Thus, the Lewis structure with O as the central atom is the major structure of HClO.