The atomic number of chromium is `24` Its electronic coefigueration in ground state in `1s^(2) 2s^(2)2p^(6)3s^(2)4s^(1) 3d^(5)` .Chromium atom by using `3` electron from `Cr ^(3+)` .A chromium atom contain `17%` morte neutron than the proton. Now answer the following questions
The number of unpaired electron in `Cr ^(3+)`ion is

Options

A. 3
B. 6
C. 5
D. 1

Explanation

To determine the number of unpaired electrons in the Cr³⁺ ion, we will follow these steps:

### Step 1: Write the electronic configuration of the neutral chromium atom (Cr).
The atomic number of chromium (Cr) is 24. Its ground state electronic configuration is:
\[ \text{Cr: } 1s^2 2s^2 2p^6 3s^2 4s^1 3d^5 \]
This can also be represented using the noble gas shorthand:
\[ \text{Cr: } [\text{Ar}] 3d^5 4s^1 \]

### Step 2: Determine the electronic configuration of the Cr³⁺ ion.
When chromium loses three electrons to form Cr³⁺, the electrons are removed first from the 4s orbital and then from the 3d orbital. Therefore, the electronic configuration for Cr³⁺ will be:
\[ \text{Cr}^{3+}: [\text{Ar}] 3d^3 \]
This means that one electron is removed from the 4s orbital and two electrons are removed from the 3d orbital.

### Step 3: Analyze the 3d subshell for unpaired electrons.
The 3d subshell can hold a maximum of 10 electrons, and in the case of Cr³⁺, we have 3 electrons in the 3d subshell. The filling of the 3d orbitals follows Hund's rule, which states that electrons will fill degenerate orbitals singly before pairing up.

The distribution of the 3 electrons in the 3d orbitals will be:
- 3d₁, 3d₂, 3d₃ (each in separate orbitals)

### Step 4: Count the number of unpaired electrons.
Since all three electrons occupy separate orbitals, they are all unpaired. Thus, the number of unpaired electrons in Cr³⁺ is:
\[ \text{Number of unpaired electrons} = 3 \]

### Final Answer:
The number of unpaired electrons in the Cr³⁺ ion is **3**.

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