Answer:
Magnesium has 2 valence electrons.
Explanation:
The atomic number of magnesium is 12. This means that it has 12 protons and 12 electrons. The first electron shell can hold 2 electrons, the second can hold 8, so the third will have 2 electrons. The outermost shell of the atom has two electrons. Therefore, magnesium has 2 valence electrons.
