# Which is the central atom in Lewis Dot Structures? [duplicate]

What is the correct Lewis structure for hypochlorous acid, a compound containing chlorine, hydrogen and oxygen?

As shown in the following video, the central atom in Lewis Dot Structures is always the least electronegative atom of all the elements that make up the atom. https://www.khanacademy.org/science/chemistry/chemical-bonds/copy-of-dot-structures/v/drawing-dot-structures

This way, you would expect chlorine to be the central atom. However, it is shown that oxygen is the central atom.

The ambiguity exists for molecules like $\ce{OCl_2}$ as well. What's the issue? Is this not a very consistent rule of thumb?

The video is wrong if it says "the central atom ... is always the least electronegative atom".

There are chlorine oxides with Cl central such as perchlorate, chlorate and $\ce{ClO2}$, even though $\ce{Cl2O}$ has O central.

There are $\ce{SeCSe}$, $\ce{CAt4}$, $\ce{NI3}$ and $\ce{Li6C}$ each with the more electronegative element central.

• How would you answer the question then? Is there always some level of doubt one would have when coming up with Lewis structures when just given the constituent atoms? – StopReadingThisUsername Dec 1 '15 at 9:27
• @Arjun I would have to say there is always some doubt. For example HNCO, HOCN, and HCNO all exist, although HNCO is most stable. en.wikipedia.org/wiki/Isocyanic_acid Additional guidelines beyond "the more electronegative element central" would be "H" is almost always on the outside, usually no lone pairs on "C", almost never more than one lone pair on nitrogen, no more than two lone pairs on "O" in a neutral molecule. – DavePhD Dec 1 '15 at 14:09