To determine the electron configuration for magnesium (Mg), let's proceed step-by-step:
1. Identify the Atomic Number:
Magnesium has an atomic number of 12. This means a neutral magnesium atom has 12 electrons.
2. Understand Electron Configuration:
The electron configuration of an element describes the distribution of electrons among the various atomic orbitals.
3. Standard Order of Filling Orbitals:
Electrons fill orbitals in a specific order based on increasing energy levels. The order of filling these orbitals is:
- 1s
- 2s
- 2p
- 3s
- 3p
- 4s
- 3d
- 4p
... and so on according to the Aufbau principle.
4. Filling the Orbitals with Electrons:
For magnesium, which has 12 electrons, we'll fill the orbitals in the following order based on the number of electrons each can hold:
- The 1s orbital can hold 2 electrons: [tex]\(1s^2\)[/tex]
- The 2s orbital can hold 2 electrons: [tex]\(2s^2\)[/tex]
- The 2p orbital can hold 6 electrons: [tex]\(2p^6\)[/tex]
- The 3s orbital can hold 2 electrons: [tex]\(3s^2\)[/tex]
Adding these up:
[tex]\[
1s^2 (2) + 2s^2 (2) + 2p^6 (6) + 3s^2 (2) = 2 + 2 + 6 + 2 = 12 \text{ electrons}
\][/tex]
5. Electron Configuration of Magnesium:
Therefore, the electron configuration for magnesium is [tex]\(1s^2 2s^2 2p^6 3s^2\)[/tex].
6. Match with Given Options:
Reviewing the given options:
- A. [tex]\(3s^2 3p^6 3d^4\)[/tex]
- B. [tex]\(1s^2 2s^2 2p^6 3s^2\)[/tex]
- C. [tex]\(1s^2 2s^2 2p^2 3s^6\)[/tex]
- D. [tex]\(1s^2 2s^2 3s^2 3p^6\)[/tex]
The correct electron configuration matches option B: [tex]\(1s^2 2s^2 2p^6 3s^2\)[/tex].
Thus, the correct electron configuration for magnesium is [tex]\(1s^2 2s^2 2p^6 3s^2\)[/tex] which corresponds to option B.
