An element belongs to group 15 and third period of the periodic table. Its electronic configuration will be

Options

A. `1s ^(2) 2s ^(2) 2p ^(3)`
B. `1s ^(2) 2s ^(2) 2p ^(4)`
C. `1s ^(2) 2s ^(2) 2p ^(6) 3s ^(2) 3p ^(3)`
D. `1s ^(2) 2s ^(2) 2p ^(6) 3s ^(2) 3p ^(2)`

Explanation

To determine the electronic configuration of an element that belongs to group 15 and the third period of the periodic table, we can follow these steps:

### Step 1: Identify the Element
- The element in group 15 and the third period is phosphorus (P).

### Step 2: Determine the Atomic Number
- The atomic number of phosphorus is 15. This means that phosphorus has 15 electrons.

### Step 3: Fill the Electron Shells
- We will fill the electron shells according to the Aufbau principle, which states that electrons occupy the lowest energy orbitals first. The order of filling is as follows:
1. 1s
2. 2s
3. 2p
4. 3s
5. 3p

### Step 4: Write the Electronic Configuration
- Fill the orbitals step by step:
- **1s**: 2 electrons → 1s²
- **2s**: 2 electrons → 2s²
- **2p**: 6 electrons → 2p⁶
- **3s**: 2 electrons → 3s²
- **3p**: 5 electrons → 3p³

- Now, we can sum up the electrons:
- 1s² + 2s² + 2p⁶ + 3s² + 3p³ = 2 + 2 + 6 + 2 + 3 = 15 electrons.

### Final Electronic Configuration
- Therefore, the electronic configuration of phosphorus (atomic number 15) is:
- **1s² 2s² 2p⁶ 3s² 3p³**

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