What are the oxidation and reduction half-reactions for Cr+F_2 -> CrF_3?

May 19, 2017

Oxidation: $C r \to C {r}^{3 +} + 3 {e}^{-}$
Reduction: ${F}_{2} + 2 {e}^{-} \to 2 {F}^{-}$
The empirical formula $C r {F}_{3}$ suggests that fluorine has more electron tendency than chromium. Thus it has a negative oxidation state number.
The fluoride ion has a $- 1$ charge as a halogen anion.
Each chromium cation binds to $3$ fluoride anion, so it has a $+ 3$ ionic charge.