Match the following, where EAN stands for Effective Atomic Number, the number of electrons on the central metal ion, including ligands in the bonding:

$\begin {array} {1 1}A.\; \text{EAN of Fe in} [Fe(CN)_6]^{4-} & a.\; 86\\ B.\; \text{EAN of Co in} [Co(NH_3)_6]^{3-} & b.\; 48\\ C.\; \text{EAN of Ni in} [Ni(CO)_4]^{3-} & c.\; 24\\ D.\; \text{EAN of Pt in} [Pt(NH_3)_6)]^{4+} & d.\;36 \end {array}$

$\begin {array} {1 1} 1 \to d \quad 2 \to d \quad 3 \to d \quad 4 \to a \\ 1 \to d \quad 2 \to c \quad 3 \to b \quad 4 \to a \\ 1 \to d \quad 2 \to c \quad 3 \to a \quad 4 \to b \\ 1 \to d \quad 2 \to b \quad 3 \to a \quad 4 \to c \end {array}$

Answer: $1 \to d \quad 2 \to d \quad 3 \to d \quad 4 \to a$
The formula for EAN is = (Z-x) + (2n), where Z = atomic number of element, x is the oxidation state of the metal, n is the number of ligands.
$\quad 1.\; \text{EAN of Fe in} [Fe(CN)_6]^{4-} = (26-2) + 2 \times 6 = 36$
$\quad 2.\; \text{EAN of Co in} [Co(NH_3)_6]^{3- } = (27-3) + 2 \times 6 = 36$
$\quad 3.\; \text{EAN of Ni in} [Ni(CO)_4]^{3-} = (28-0) + 2 \times 4 = 36$
$\quad 4.\; \text{EAN of Pt in} [Pt(NH_3)_6)]^{4+} = (78-4) + 2 \times 6 = 86$
answered Jan 30, 2014
edited Aug 6, 2014