3.51

[Evelyn L 1H]

In 51, it asks for two Lewis structures with different atom arrangements for HClO and to select the most likely structure by identifying the structure with the formal charges closest to zero.

Since Cl has the lowest electronegativity, I thought it was supposed to be in the middle and made a structure with no formal charges that looked like: H (single bond) Cl (double bond) O with 2 lone pairs on both the Cl and O.

However, the answer key said that the most stable structure is
H (single bond) O (single bond) Cl with 2 lone pairs on O and 3 lone pairs on Cl

Why is O in the middle if Cl is the least electronegative element and why wasn't the structure I made with Cl in the middle correct?

[Scott Chin_1E]

Oxygen is in the middle of the structure because it has a higher first ionization energy value. This means it is less likely to give off an electron, and more likely will hold onto its electron and thus draw other electrons towards it. The electronegativity value for Chlorine means that it will more likely pull the electrons closer to the Chlorine atom when sharing an electron. I believe that the ionization energy value determines the position of the atom in the center of the Lewis structure, not the electronegativity value.

[RussellChin_3A]

In addition to Scott's answer, one of the primary reasons why your lewis structure is not correct compared to the answer is that if you put Cl in the middle, it takes on 10 e-, which is not possible for it to do, since it goes over its octet. Hope this helps!

[Evelyn L 1H]

I've heard electronegativity and ionization energy being used interchangeably by multiple different UA's. But either way, isn't it the least highest ionization energy that is the central atom, which in this case is Chlorine. And Chlorine can have an expanded octet.