In the ground state, an element has 13 electrons in its M-shell. The element is

Options

A. Manganese
B. Chromium
C. Nickel
D. Iron

Explanation

To determine the element with 13 electrons in its M-shell, we need to analyze the electron configuration and the distribution of electrons in the shells.

### Step-by-Step Solution:

1. **Understanding Electron Shells**:
- The electron shells are labeled as K, L, M, N, etc.
- K-shell (1st shell) can hold a maximum of 2 electrons.
- L-shell (2nd shell) can hold a maximum of 8 electrons.
- M-shell (3rd shell) can hold a maximum of 18 electrons but can be filled in a specific order.

2. **Identifying the M-shell Configuration**:
- The M-shell can contain electrons in the 3s, 3p, and 3d subshells.
- The filling order of the subshells is:
- 3s can hold 2 electrons,
- 3p can hold 6 electrons,
- 3d can hold 10 electrons.

3. **Total Electrons in M-shell**:
- Given that the M-shell has 13 electrons, we can fill it as follows:
- 3s: 2 electrons
- 3p: 6 electrons
- 3d: 5 electrons
- Therefore, the configuration for the M-shell is 3s² 3p⁶ 3d⁵.

4. **Calculating Total Electrons**:
- The total number of electrons in the atom can be calculated by adding the electrons in all shells:
- K-shell: 2 electrons (1s²)
- L-shell: 8 electrons (2s² 2p⁶)
- M-shell: 13 electrons (3s² 3p⁶ 3d⁵)
- Total = 2 (K) + 8 (L) + 13 (M) = 23 electrons.

5. **Identifying the Element**:
- The atomic number of the element is 23, which corresponds to Vanadium (V) in the periodic table.

### Final Answer:
The element with 13 electrons in its M-shell is Vanadium (V).

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