Question

What is EAN of Co in \( [Co(NH_{3})_{6}]^{3+} \)?

• A. 36
• B. 34
• C. 38
• D. 32

Hint:

EAN calculation: $Z - \text{Oxidation State} + 2 \times \text{Coordination Number}$.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
Effective Atomic Number (EAN) is the total number of electrons around the central metal atom/ion in a complex.
Step 2: Key Formula or Approach:
\[ \text{EAN} = Z - X + Y \]
Where:
\( Z \) = Atomic number of central metal atom
\( X \) = Oxidation state of central metal atom
\( Y \) = Total number of electrons donated by ligands
Step 3: Detailed Explanation:
For the complex \( [Co(NH_{3})_{6}]^{3+} \):
- Central metal is Cobalt (Co). Atomic number \( Z = 27 \).
- Let oxidation state be \( x \). \( x + 6(0) = +3 \Rightarrow x = +3 \). So, \( X = 3 \).
- There are 6 ammonia (\( NH_{3} \)) ligands. Each is a monodentate ligand donating 2 electrons.
- Total electrons donated \( Y = 6 \times 2 = 12 \).
Calculation:
\[ \text{EAN} = 27 - 3 + 12 \]
\[ \text{EAN} = 24 + 12 = 36 \]
Step 4: Final Answer:
The EAN of Co in the given complex is 36.