The number of unpaired electrons in the scandium atom is

Options

A. 1
B. 2
C. 0
D. 3

Answer

To determine the number of unpaired electrons in a scandium atom, we can follow these steps:

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

### Step 2: Write the Electronic Configuration
The electronic configuration of scandium can be derived from its atomic number. The electrons fill the orbitals in the following order:
- The first 18 electrons fill the orbitals up to argon (1s² 2s² 2p⁶ 3s² 3p⁶).
- The remaining 3 electrons will fill the 3d and 4s orbitals. Thus, the electronic configuration of scandium is:
\[ \text{Sc: } [\text{Ar}] 3d^1 4s^2 \]

### Step 3: Analyze the Electron Configuration
From the electronic configuration:
- The 4s orbital has 2 electrons, which are paired.
- The 3d orbital has 1 electron, which is unpaired.

### Step 4: Count the Unpaired Electrons
In the case of scandium:
- The 4s orbital is completely filled (2 paired electrons).
- The 3d orbital has 1 unpaired electron.

Therefore, the total number of unpaired electrons in a scandium atom is **1**.

### Final Answer
The number of unpaired electrons in the scandium atom is **1**.

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