Question

What is the effective atomic number of Fe in [Fe(CN)\(_6\)]\(^{4-}\) (At. no. of Fe = 26)?

• A. 34
• B. 26
• C. 36
• D. 35

Hint:

To calculate the effective atomic number (EAN), add the atomic number of the metal ion and the number of electrons donated by the ligands.

Answer 1

The Correct Option is C

Step 1: Understanding the Effective Atomic Number (EAN).
The effective atomic number (EAN) is calculated by adding the atomic number of the central metal ion to the number of electrons donated by the ligands. In this case, Fe has an atomic number of 26. The cyanide ligand (CN\(^-\)) donates 2 electrons. Since there are six cyanide ions, the total number of electrons donated by the ligands is \(6 \times 2 = 12\). The EAN is thus: \[ \text{EAN} = 26 (\text{Fe}) + 12 (\text{from CN}^-) = 36 \]
Step 2: Analyzing the options.
(A) 34: Incorrect. This is not the correct EAN value.
(B) 26: Incorrect. This is the atomic number of Fe, not the effective atomic number.
(C) 36: Correct. The EAN is 36 for the [Fe(CN)\(_6\)]\(^{4-}\) complex.
(D) 35: Incorrect. This is not the correct EAN value.

Step 3: Conclusion.
The effective atomic number is 36, corresponding to option (C).