Which one of the following is a correct electronic configuration of sodium?

Options

A. 2, 8
B. 8, 2, 1
C. 2, 8, 1
D. 2, 8, 1

Answer

To determine the correct electronic configuration of sodium, we will follow these steps:

### Step 1: Identify the Atomic Number
The atomic number of sodium (Na) is 11. This means that a sodium atom has 11 electrons.

### Step 2: Understand Electron Shells
Electrons are arranged in shells around the nucleus. The maximum number of electrons that can be accommodated in each shell is given by the formula 2n², where n is the shell level:
- K shell (n=1) can hold 2 electrons.
- L shell (n=2) can hold 8 electrons.
- M shell (n=3) can hold 18 electrons (but for sodium, we only need to fill 1 electron in this shell).

### Step 3: Fill the Electron Shells
1. Fill the K shell first:
- K shell can hold 2 electrons: **2 electrons** in K shell.

2. Fill the L shell next:
- L shell can hold 8 electrons: **8 electrons** in L shell.

3. Place the remaining electrons in the M shell:
- Sodium has 11 electrons total, so after filling K and L shells (2 + 8 = 10), we have 1 electron left for the M shell.

### Step 4: Write the Electronic Configuration
Based on the distribution of electrons:
- K shell: 2 electrons
- L shell: 8 electrons
- M shell: 1 electron

Thus, the electronic configuration of sodium is written as **2, 8, 1**.

### Conclusion
The correct electronic configuration of sodium is **2, 8, 1**.

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