Which of the following electronic configuration belong to transition elements?

Options

A. `KL, 3s^(2)p^(6)d^(5), 4s^(1)`
B. `KL, 3s^(2) p^(6)d^(10),4s^(2)p^(3)`
C. `KL, 3s^(2)p^(6)d^(10), 4s^(2)p^(1)`
D. `KLM, 4s^(2)p^(6)d^(10), 5s^(2)p^(1)`

Answer

To determine which of the given electronic configurations belongs to transition elements, we can follow these steps:

### Step 1: Understand Transition Elements
Transition elements are defined as the d-block elements in the periodic table, which are located between the s-block and p-block elements. These elements have partially filled d-orbitals.

### Step 2: Analyze the Given Electronic Configurations
Let’s analyze the electronic configurations provided in the question. We will identify the valence electrons and their respective orbitals.

1. **Configuration 1**:
- Valence electrons are in the d-orbital.

2. **Configuration 2**:
- Valence electrons are in the p-orbital.

3. **Configuration 3**:
- Valence electrons are in the p-orbital.

4. **Configuration 4**:
- Valence electrons are in the p-orbital.

### Step 3: Count Electrons and Identify the Atomic Number
Next, we will count the total number of electrons in each configuration to find the atomic number and identify the element.

1. **Configuration 1**:
- K shell: 2 electrons
- L shell: 8 electrons
- 3S: 2 electrons
- 3P: 6 electrons
- 3D: 5 electrons
- 4S: 1 electron
- Total: 2 + 8 + 2 + 6 + 5 + 1 = 24 electrons (Atomic number 24 = Chromium, a transition element)

2. **Configuration 2**:
- K shell: 2 electrons
- L shell: 8 electrons
- 3S: 2 electrons
- 3P: 6 electrons
- 3D: 10 electrons
- 4S: 2 electrons
- 4P: 3 electrons
- Total: 2 + 8 + 2 + 6 + 10 + 2 + 3 = 33 electrons (Atomic number 33 = Germanium, a p-block element)

3. **Configuration 3**:
- K shell: 2 electrons
- L shell: 8 electrons
- 3S: 2 electrons
- 3P: 6 electrons
- 3D: 10 electrons
- 4S: 2 electrons
- 4P: 1 electron
- Total: 2 + 8 + 2 + 6 + 10 + 2 + 1 = 31 electrons (Atomic number 31 = Gallium, a p-block element)

4. **Configuration 4**:
- K shell: 2 electrons
- L shell: 8 electrons
- M shell: 18 electrons
- 4S: 2 electrons
- 4P: 6 electrons
- 4D: 10 electrons
- 5S: 2 electrons
- 5P: 1 electron
- Total: 2 + 8 + 18 + 2 + 6 + 10 + 2 + 1 = 51 electrons (Atomic number 51 = Antimony, a p-block element)

### Step 4: Conclusion
From the analysis, only the first configuration corresponds to a transition element (Chromium). The other configurations correspond to elements in the p-block.

**Final Answer**: The electronic configuration that belongs to a transition element is the first one.

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