If Pauli's exclusion principle is not known, the electronic arrangement of lithium atom is

Options

A. `1s^(2) 2s^(1)`
B. `1s^(1) 2s^(2)`
C. `1s^(3)`
D. `1s^(2) 2s^(1) 2p^(1)`

Answer

To determine the electronic arrangement of a lithium atom if Pauli's exclusion principle is not known, we need to analyze the filling of electrons in atomic orbitals without considering the restrictions imposed by this principle.

### Step-by-Step Solution:

1. **Understanding Lithium Atom**:
- Lithium (Li) has an atomic number of 3, which means it has 3 electrons.

2. **Filling Order of Electrons**:
- Normally, electrons fill the orbitals in order of increasing energy levels, following the Aufbau principle. The order of filling is 1s, 2s, 2p, etc.

3. **Filling the 1s Orbital**:
- The first two electrons will occupy the 1s orbital. According to the Aufbau principle, the 1s orbital can hold a maximum of 2 electrons.

4. **Filling the 2s Orbital**:
- The third electron will then go into the next available orbital, which is the 2s orbital.

5. **Resulting Electronic Configuration**:
- Therefore, without the Pauli exclusion principle, we could fill the orbitals as follows:
- 1s: 2 electrons
- 2s: 1 electron
- This gives us the electronic configuration of lithium as **1s² 2s¹**.

### Conclusion:
If Pauli's exclusion principle is not known, the electronic arrangement of the lithium atom would be **1s² 2s¹**.

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