What is the electron configuration of a Mn atom in the ground state? A) 15252p6382 B) 18282p6383p6453d C) 152522p63523p64513d4p1 D) 1522522p6353pf3d
The Correct Answer and Explanation is:
The correct answer is: B) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁵
Explanation
Manganese (Mn) is a transition metal with atomic number 25, which means it has 25 electrons in its neutral, ground state. To write its electron configuration, we fill the atomic orbitals in order of increasing energy using the Aufbau principle, Pauli exclusion principle, and Hund’s rule.
The general order of filling orbitals by energy is:
1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p…
Now, let us fill in the electrons for Mn:
- 1s²: 2 electrons → total = 2
- 2s²: 2 electrons → total = 4
- 2p⁶: 6 electrons → total = 10
- 3s²: 2 electrons → total = 12
- 3p⁶: 6 electrons → total = 18
- 4s²: 2 electrons → total = 20
- 3d⁵: 5 electrons → total = 25
This completes the full 25 electrons, so the electron configuration is:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁵
We place the electrons in the 4s orbital before the 3d because the 4s has lower energy when empty or partially filled. However, once filled, 3d becomes lower in energy, which explains why in ion formation, Mn loses the 4s electrons first.
Looking at the choices:
- A is missing orbitals and not well structured.
- B is correct: It clearly matches the proper order and count.
- C and D have wrong subscripts and incorrect placement of orbitals.
Therefore, option B is the correct and complete electron configuration for a ground-state manganese atom.
