The atomic number of an element is 14. The number of orbitals containing electron pairs in the valence shell is:

Options

A. 2
B. 1
C. 4
D. 6

Answer

To solve the question regarding the number of orbitals containing electron pairs in the valence shell of an element with atomic number 14, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Element**:
The atomic number 14 corresponds to the element Silicon (Si).

2. **Write the Electronic Configuration**:
The electronic configuration of Silicon can be determined by filling the orbitals according to the Aufbau principle.
- The configuration is:
- 1s² 2s² 2p⁶ 3s² 3p²
- This shows that Silicon has a total of 14 electrons.

3. **Determine the Valence Shell**:
The valence shell is the outermost shell that contains electrons. For Silicon, the outermost shell is the third shell (n=3).
- The orbitals in the valence shell are:
- 3s and 3p.

4. **Count the Electrons in the Valence Shell**:
- In the 3s orbital, there are 2 electrons (3s²).
- In the 3p orbital, there are 2 electrons (3p²).
- Therefore, the total number of electrons in the valence shell is 4 (2 from 3s and 2 from 3p).

5. **Identify the Number of Orbitals with Electron Pairs**:
- An orbital can hold a maximum of 2 electrons.
- The 3s orbital contains 2 electrons, which forms 1 pair.
- The 3p orbital has 2 electrons distributed among the three 3p orbitals (3p_x, 3p_y, 3p_z). Since each of these orbitals can hold 2 electrons, but here we have only 2 electrons, they will occupy two of the three available p orbitals singly (according to Hund's rule) and thus do not form a pair in the 3p orbitals.
- Therefore, only the 3s orbital contains a complete pair of electrons.

6. **Conclusion**:
The number of orbitals containing electron pairs in the valence shell of Silicon (atomic number 14) is **1** (the 3s orbital).

### Final Answer:
The number of orbitals containing electron pairs in the valence shell is **1**.

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