Electronic configuration of `._(21)Sc` is

Options

A. `1s^(2) 2s^(2)2p^(6) 3s^(2) 3p^(6) 4s^(2) 3d^(1)`
B. `1s^(2) 2s^(2)2p^(6) 3s^(2) 3p^(6) 4s^(1) 3d^(2)`
C. `1s^(2) 2s^(2)2p^(6) 3s^(2) 3p^(6) 4s^(0) 3d^(3)`
D. `1s^(2) 2s^(2)2p^(6) 3s^(2) 3p^(6) 4s^(2) 3d^(2)`

Explanation

To determine the electronic configuration of Scandium (Sc) with atomic number 21, we will follow these steps:

### Step 1: Understand the Atomic Number
The atomic number of Scandium (Sc) is 21. This means that a neutral Sc atom has 21 electrons.

### Step 2: 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
6. 4s
7. 3d

### Step 3: Count the Electrons in Each Shell
Now, we will fill each shell with the maximum number of electrons it can hold:

- **1s** can hold 2 electrons: 1s²
- **2s** can hold 2 electrons: 2s²
- **2p** can hold 6 electrons: 2p⁶
- **3s** can hold 2 electrons: 3s²
- **3p** can hold 6 electrons: 3p⁶
- **4s** can hold 2 electrons: 4s²
- **3d** can hold 10 electrons, but we will only fill 1 for Scandium: 3d¹

### Step 4: Write the Full Electronic Configuration
Now, we will combine all the filled orbitals to write the full electronic configuration:

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹

### Final Answer
The electronic configuration of Scandium (Sc) is:
**1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹**

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