The effective atomic number for the complex ion [Ni(CN)4]2– is — Coordination Compounds Chemistry Question

💡 Solution & Explanation

# Finding Effective Atomic Number (EAN) **Formula:** $\text{EAN} = Z - \text{(oxidation state)} + \text{(electrons donated by ligands)}$ **Step 1: Identify the metal and its oxidation state** - Metal: Ni (Nickel) - Atomic number: $Z = 28$ - In $[Ni(CN)_4]^{2-}$, let oxidation state = $x$ - $x + 4(-1) = -2$ → $x = +2$ **Step 2: Count electrons donated by ligands** - Ligand: $CN^-$ (cyanide) - Each $CN^-$ donates 2 electrons (acts as a divalent donor) - 4 ligands × 2 electrons = **8 electrons** **Step 3: Calculate EAN** $$\text{EAN} = 28 - 2 + 8 = 34$$ **Step 4: Verify the result** - EAN = 34 corresponds to **Kr (Krypton)**, a noble gas configuration - This is characteristic of square planar geometry with $d^8$ metals like Ni²⁺ - The stable configuration confirms $Ni(CN)_4$ achieves noble gas electron count **Answer: EAN = 34**