Question

Find the EAN of Zn in $[Zn(NH_3)_4]^{2+}$?

• A. 38
• B. 37
• C. 36
• D. 35

Hint:

The EAN rule suggests that complexes are highly stable if their EAN perfectly matches the atomic number of the next noble gas. In this case, 36 is the exact atomic number of the noble gas Krypton (Kr).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Effective Atomic Number (EAN) represents the total number of electrons surrounding the nucleus of a metal atom in a complex.

Step 2: Formula Application:
$EAN = Z - ON + 2(CN)$, where $Z$ is atomic number, $ON$ is oxidation number, and $CN$ is coordination number.

Step 3: Explanation:
For Zinc ($Zn$): $Z = 30$. In $[Zn(NH_3)_4]^{2+}$, ammonia is neutral, so $ON$ of $Zn = +2$. There are 4 ligands, so $CN = 4$. $EAN = 30 - 2 + 2(4) = 28 + 8 = 36$.

Step 4: Final Answer:
The EAN of Zn is 36.