[a student]

can a radical act as a nucleophile in a substitution reaction? 

[Schrödinger]

My teacher told me that free radicals are electrophiles, as they are electron deficient(octet not complete).

I think it cannot behave as a nucluephile as it neither possesses extra negative charges, nor a lone pair of electrons(excess).

The free unpaired electron will always try to become paired. That is, it has thirst for electrons.

[a student]

thanks