Calculate the electronegativity of silicon atom using Allred-rochow's method. If covalent radius of silicon is 1.0 A. (rounded in nearest integer value).

Answer

To calculate the electronegativity of a silicon atom using the Allred-Rochow method, follow these steps:

### Step 1: Identify the Covalent Radius
The covalent radius of silicon is given as 1.0 Å (angstrom).

### Step 2: Calculate the Effective Nuclear Charge (Z_eff)
1. Write the electronic configuration of silicon:
- Silicon (Si) has an atomic number of 14, so its electronic configuration is \(1s^2 2s^2 2p^6 3s^2 3p^2\).

2. Apply Slater's rules to calculate \(Z_{eff}\):
- For the outermost electrons (3s and 3p), we consider the shielding contributions:
- Electrons in the same shell (n=3): 0.35 each (2 electrons)
- Electrons in the shell below (n=2): 0.85 each (8 electrons)
- Electrons in the shell below that (n=1): 1.00 each (2 electrons)

- The calculation for shielding (S) is:
\[ S = (0.35 \times 2) + (0.85 \times 8) + (1.00 \times 2) = 0.70 + 6.80 + 2.00 = 9.50 \]

- Now, calculate \(Z_{eff}\):
\[ Z_{eff} = Z - S = 14 - 9.50 = 4.50 \]

### Step 3: Use the Allred-Rochow Equation
The Allred-Rochow equation for electronegativity (\(\chi\)) is given by:
\[ \chi = 0.359 Z_{eff} + 0.744 \frac{1}{r} \]
Where \(r\) is the covalent radius in angstroms.

### Step 4: Substitute Values into the Equation
1. Substitute \(Z_{eff} = 4.50\) and \(r = 1.0\):
\[ \chi = 0.359 \times 4.50 + 0.744 \times \frac{1}{1.0} \]

2. Calculate:
\[ \chi = 1.6155 + 0.744 = 2.3595 \]

### Step 5: Round to the Nearest Integer
The final step is to round the value to the nearest integer:
\[ \chi \approx 2 \]

### Final Answer
The electronegativity of the silicon atom, rounded to the nearest integer, is **2**.

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