An element having electronic configuration `1s^2 2s^2 2p^6 3s^2 3p^6 3d^(10) 4s^1` is related to which block in the periodic table:

Options

A. s–block
B. p–block
C. d–block
D. f–block

Answer

To determine which block in the periodic table an element belongs to based on its electronic configuration, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Electronic Configuration**:
The given electronic configuration is `1s^2 2s^2 2p^6 3s^2 3p^6 3d^(10) 4s^1`.

2. **Locate the Last Electron**:
The last electron in this configuration is in the `4s` orbital, as indicated by the `4s^1` part of the configuration.

3. **Determine the Block**:
- In the periodic table, elements are categorized into blocks based on the subshell that contains the last electron:
- **s-block**: Last electron enters an s-orbital.
- **p-block**: Last electron enters a p-orbital.
- **d-block**: Last electron enters a d-orbital.
- **f-block**: Last electron enters an f-orbital.
- Since the last electron is in the `4s` orbital, it initially suggests that the element is in the s-block.

4. **Consider the d-Orbital Filling**:
- However, we must also consider the presence of the `3d` orbital in the configuration. The `3d` orbital is filled before the `4s` orbital due to the energy levels.
- According to the Aufbau principle and the n + l rule, the `3d` orbital has a higher energy than the `4s` orbital, but since the `3d` subshell is already filled (with 10 electrons), the element is actually part of the d-block.

5. **Conclusion**:
The element with the electronic configuration `1s^2 2s^2 2p^6 3s^2 3p^6 3d^(10) 4s^1` is a member of the **d-block** of the periodic table.