Give `EAN` value of Mg in `[Mg(EDTA)]^(2-)` .

Options

A. `16`
B. `20`
C. `22`
D. `18`

Explanation

To find the Effective Atomic Number (EAN) of magnesium in the complex \([Mg(EDTA)]^{2-}\), we can follow these steps:

### Step 1: Identify the Atomic Number of Magnesium
The atomic number of magnesium (Mg) is 12.

### Step 2: Determine the Oxidation State of Magnesium
In the complex \([Mg(EDTA)]^{2-}\), the EDTA ligand is a hexadentate ligand and carries a -4 charge. Since the overall charge of the complex is -2, we can set up the following equation to find the oxidation state (X) of magnesium:

\[ X + (-4) = -2 \]

Solving for X gives:

\[ X = -2 + 4 = +2 \]

Thus, the oxidation state of magnesium in this complex is +2.

### Step 3: Count the Lone Pair Donating Sites
EDTA is a hexadentate ligand, meaning it has 6 lone pair donating sites.

### Step 4: Apply the EAN Formula
The formula for Effective Atomic Number (EAN) is given by:

\[ EAN = \text{Atomic Number of Central Metal} - \text{Oxidation State} + 2 \times \text{Number of Lone Pair Donating Sites} \]

Substituting the values we have:

\[ EAN = 12 - 2 + 2 \times 6 \]

### Step 5: Calculate the EAN
Now, we can perform the calculation:

\[ EAN = 12 - 2 + 12 = 22 \]

### Conclusion
The Effective Atomic Number (EAN) of magnesium in the complex \([Mg(EDTA)]^{2-}\) is **22**.

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