[BrockaFloka]

The question is:

The electron affinity of SF5 is higher than that of S, F, or any other single atom. Explain this.

my attempt so far is saying that the electron density around the S in SF5 is low and its nucleus has a higher positive charge than atomic fluorine, so conditions to add another electron are better than in F. Does this sound correct?

We are doing some stuff with valence bond theory and MO theory in class but I do not know if those are applicable to this question
thanks for any *delete me*

[Schrödinger]

Yes, your explanation does seem correct to me.

However, another explanation that I could come up with was the extremely almost-symmetrical nature of the molecule SF₅. Which means, given an opportunity, it would easily attract another unpaired electron (say from another F atom) to attain the octahedral geometry of SF₆. Once this structure is attained, all electrons are paired, all sp³d² orbitals are filled up doubly (assume hybridization at this stage).