The atomic number of an element is 17. The number of orbitals containing electron pairs in the valence shell is:

Options

A. 2
B. 3
C. 6
D. 8

Explanation

To solve the problem, we need to determine the number of orbitals containing electron pairs in the valence shell of an element with an atomic number of 17.

### Step-by-Step Solution:

1. **Identify the Element**:
The atomic number 17 corresponds to the element Chlorine (Cl).

2. **Write the Electronic Configuration**:
The electronic configuration of Chlorine can be determined by filling the orbitals according to the Aufbau principle:
- 1s² 2s² 2p⁶ 3s² 3p⁵

3. **Determine the Valence Shell**:
The valence shell for Chlorine is the third shell (n=3), which includes the 3s and 3p orbitals.

4. **Count the Electrons in the Valence Shell**:
- In the 3s orbital, there are 2 electrons (3s²).
- In the 3p orbital, there are 5 electrons (3p⁵).

5. **Identify the Orbitals in the Valence Shell**:
- The 3s orbital can hold a maximum of 2 electrons and is completely filled.
- The 3p orbital consists of three sub-orbitals: 3p_x, 3p_y, and 3p_z. The 5 electrons in the 3p orbital will occupy these sub-orbitals.

6. **Determine the Electron Pairing**:
- The 3s orbital has 2 electrons, which form 1 pair.
- The 3p orbitals (3p_x, 3p_y, 3p_z) will have the 5 electrons distributed as follows:
- 3p_x: 2 electrons (1 pair)
- 3p_y: 1 electron (unpaired)
- 3p_z: 1 electron (unpaired)
- Therefore, only the 3s and 3p_x orbitals contain electron pairs.

7. **Count the Orbitals with Electron Pairs**:
- 3s: 1 orbital with an electron pair
- 3p_x: 1 orbital with an electron pair
- 3p_y and 3p_z do not contain pairs.
- Total: 2 orbitals (3s and 3p_x) contain electron pairs.

### Final Answer:
The number of orbitals containing electron pairs in the valence shell is **2**.