Sapling #9

[SamayaJoshi1A]

Can someone explain to me Sapling Question 9, specifically the plausibility based on oxidation section. Not sure how the two relate exactly.

[edward_brodell_3K]

Since there are a certain number of O atoms and only one Cl atom, both Cl and O want to gain electrons. O needs two more electrons to reach its octet, but Cl wants to gain an electron, since its outermost shell has 7 valence electrons. However, based on formal charge, and the idea that we want the sum of absolute values of formal charges for each atom to be as closest to zero, the most plausible structure will be one with bonds that match the measured lengths. Since Cl can also achieve a full outermost shell, by emptying its outermost shell with 7 valence electrons and so now the previous shell will be stable enough for the Cl atom. If the structure correctly matches that these 7 electrons are being delocalized, then the Cl will have the oxidation state that it has because it is sharing them with the more electronegative atoms. Structures with 7 electrons shared through bonds, or 8 electrons (7 delocalized in bonds, and 1 shared), are stable enough for the atom to remain interacting.

[Melanie Lin 3E]

Hi Samaya! Regarding the oxidation thing, the problem meant to show you that you rely more on formal charge than oxidation numbers to see which structures are closer to the actual structure of the molecule.

[Jeffrey Fenn 1G]

Does anyone know if oxidation numbers will be on the midterm?