Question

The effective atomic number of central Cu (at. no. 29) metal in [Cu(NH\(_3\))\(_4\)] SO\(_4\) is

• A. 29
• B. 30
• C. 35
• D. 36

Hint:

EAN = Z - Oxidation State + 2(CN). A stable complex often has an EAN equal to the next noble gas configuration (36 for Kr, 54 for Xe).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Effective Atomic Number (EAN) = Atomic number of metal - Oxidation state + 2 × (Coordination number).
Step 2: Detailed Explanation:
In [Cu(NH\(_3\))\(_4\)]SO\(_4\), the complex ion is [Cu(NH\(_3\))\(_4\)]\(^{2+}\). NH\(_3\) is a neutral ligand. Oxidation state of Cu: Let x be the oxidation state. x + 0 = +2 ⇒ x = +2. Cu (Z = 29) in +2 state has 27 electrons. Each NH\(_3\) donates 2 electrons. Total electrons donated = 4 × 2 = 8. EAN = 27 + 8 = 35.
Step 3: Final Answer:
The effective atomic number is 35, option (C).