What is effective atomic number of $\mathrm{Pt} \operatorname{in}\left[\mathrm{Pt}\left(\mathrm{NH}_3\right)_4\right]^{2+}$ ? (Given atomic number of $\mathrm{Pt}=78$)
76
84
72
86
Solution
$\left[\mathrm{Pt}\left(\mathrm{NH}_3\right)_4\right]^{2+} \Rightarrow \mathrm{Pt}^{2+}$
$\begin{array}{|l|l|l|l|l|l|}
\hline \text{Complex} & \text{Metal} & \begin{array}{l}\text {Atomic } \\
\text {number of } \\
\text {metal Z }\end{array} & \begin{array}{l}\text {Number of } \\
\text {electrons lost } \\
\text {by metal X }\end{array} & \begin{array}{l}\text {Number of } \\
\text {electrons } \\
\text {from } \\
\text {ligands Y }\end{array} & EAN = Z-X + Y \\
\hline\left[\mathrm{Pt}\left(\mathrm{NH}_3\right)_4\right]^{2+} & \mathrm{Pt} & 78 & 2 & 4 \times 2=8 & 78-2+8=84 \\
\hline
\end{array}$