Question

The EAN of nickel in $\text{Ni}{{\left( \text{CO} \right)}_{\text{4}}}$ is:
A. 36
B. 38
C. 28
D. 454

Answer 1

Hint: To solve this question, we should be having knowledge about the concept of EAN. There is a specific rule to find the EAN of any element. Before we move on to solve the question, we should also know that the EAN is valid for most of the carbonyls.

Complete step-by-step answer:
The EAN rule or the effective atomic number rule states that the total number of electrons linked with the central metal atom or ion in a complex plus the electrons donated by the ligand is known as the effective atomic number. The EAN or the effective atomic number is also defined as an attainment of noble gas configuration.
Now, moving on to the compound that is mentioned in the question.
The formula of EAN is given below:
$\text{EAN = Z - x + 2nL}$
Let us define the various quantities that the formula of EAN represents.
Z represents the atomic number of the metal which is present in the complex ion.
x represents the oxidation state of the metal which is present in the complex ion.
n represents the number of ligands.
L represents the number of coordinate bonds that are formed by the ligands.
Now, moving on to the compound that is present in the question.
So for $\text{Ni}{{\left( \text{CO} \right)}_{\text{4}}}$
Z is 28, because the atomic number of Nickel is 28, oxidation state of the metal in the central atom is 0, number of ligands is 4 and the value of L is 1 because there is 1 coordinate bond that is formed by the ligands.
So, putting values of the $\text{Ni}{{\left( \text{CO} \right)}_{\text{4}}}$ in the formula of EAN.
So, EAN of $\text{Ni}{{\left( \text{CO} \right)}_{\text{4}}}$ is,
$\begin{align}
  & \text{ }\!\![\!\!\text{ 28 - 0 + 2 }\!\!\times\!\!\text{ 4 }\!\!\times\!\!\text{ 1 }\!\!]\!\!\text{ } \\
 & \text{= 28 + 8} \\
 & \text{= 36} \\
\end{align}$

Therefore, the correct answer is Option A.

Note: The main purpose of the EAN rule is to represent the total number of electrons surrounding the nucleus of a metal atom in a metal complex. It is composed of the metal atom’s electrons and the bonding electrons from the surrounding electron – donating atoms and molecules.