The two electrons in helium atom

Options

A. occupy different shells
B. have different spins
C. have the same spins
D. occupy different subshells of the same sabshell

Explanation

To solve the question regarding the two electrons in a helium atom, we need to analyze the electronic configuration and the principles governing electron arrangement in orbitals.

### Step-by-Step Solution:

1. **Identify the Atomic Number and Configuration**:
- Helium (He) has an atomic number of 2, meaning it has 2 electrons.
- The electronic configuration of helium is \(1s^2\), which indicates that both electrons are in the first shell (n=1) and in the s subshell.

2. **Understanding Shells and Subshells**:
- The principal quantum number (n) for helium is 1, indicating that it is in the first shell.
- The subshell is 's', which can hold a maximum of 2 electrons in one orbital.

3. **Electron Spin**:
- According to the Pauli Exclusion Principle, no two electrons in the same orbital can have the same spin. Therefore, the two electrons in the helium atom must have opposite spins.
- This means one electron will have a spin of +1/2 (spin-up) and the other will have a spin of -1/2 (spin-down).

4. **Evaluating the Options**:
- **Option A: Occupy different shells** - This is false because both electrons are in the same shell (n=1).
- **Option B: Have different spins** - This is true as explained above.
- **Option C: Have the same spin** - This is false because they cannot have the same spin in the same orbital.
- **Option D: Occupy different subshells of the same shell** - This is false since there is only one subshell (1s) in the first shell.

5. **Conclusion**:
- The correct answer is **Option B: Have different spins**.