Question

What is the $\frac{EAN}{9}$ (effective atomic number) of the underlined atoms in $\underset{–}{Ni}(CO{)}_4$?

Answer 1

The expression for the effective atomic number EAN is as given below:
$EAN=Z-X+Y$

Here, Z is the atomic number of metal, X is the number of electrons lost during the formation of the metal ion from its atom and Y is the number of electrons donated by the ligands.

For $\underset{–}{Ni}(CO{)}_4$, $Z=28,X=0$ and $Y=4\times 2=8e^{-}$.

Hence, $EAN=28-0+8=36$.

Hence, the EAN of $\underset{–}{Ni}(CO{)}_4$ is 36.

$\to \frac{EAN}{9}=\frac{36}{9}=4$