Question

Determine the sum of oxidation state and EAN of the central atom/ion in $\left[Fe\right(CN{)}_6{]}^{3-}$.

Answer 1

In $\left[Fe\right(CN{)}_6{]}^{3-}$, valency of cyanide ion is -1, thus the oxidation no. of Fe is 3.
Coordination no. of Fe is 6 as it is attached to 6 $C{N}^{-}$ ions.
EAN is the effective atomic number and is thus, the total no. of electrons surrounding the nucleus of Fe metal, which is equal to 26 electrons of Fe plus the 6 electrons of $C{N}^{-}$ ions plus 3 electrons as the complex carries -3 charge. Thus, $EAN=26+6+3=35$ .

So, Sum = 35+3 = 38.