Number of unpaired electrons in the electronic configuration `1s^(2)2s^(2)2p^(4)` is

Options

A. 2
B. 3
C. 4
D. 6

Answer

To determine the number of unpaired electrons in the electronic configuration `1s^(2)2s^(2)2p^(4)`, we can follow these steps:

### Step 1: Understand the electronic configuration
The electronic configuration given is `1s^(2)2s^(2)2p^(4)`. This means:
- The `1s` orbital has 2 electrons.
- The `2s` orbital has 2 electrons.
- The `2p` orbital has 4 electrons.

### Step 2: Fill the orbitals according to the Pauli Exclusion Principle and Hund's Rule
1. **1s Orbital**: This can hold a maximum of 2 electrons. Since it has 2 electrons, they are paired.
- Configuration: ↑↓ (paired)

2. **2s Orbital**: This also holds a maximum of 2 electrons. Since it has 2 electrons, they are paired.
- Configuration: ↑↓ (paired)

3. **2p Orbital**: This can hold a maximum of 6 electrons. We have 4 electrons to place in the 2p orbital. According to Hund's Rule, we first fill each of the three p orbitals singly before pairing them. Thus, the filling will be as follows:
- Configuration: ↑↓ ↑ ↑ (where the first two electrons pair in one p orbital, and the remaining two occupy separate p orbitals)

### Step 3: Count the unpaired electrons
From the configuration of the 2p orbital:
- The first p orbital has 2 electrons (paired).
- The second p orbital has 1 electron (unpaired).
- The third p orbital has 1 electron (unpaired).

Thus, there are **2 unpaired electrons** in the 2p orbital.

### Final Answer
The number of unpaired electrons in the electronic configuration `1s^(2)2s^(2)2p^(4)` is **2**.

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