Question: how many valence electrons does a neutral magnesium (mg) atom have?
Answer: Now, when the magnesium cation is formed, two electrons, hence the 2+ charge of the cation, are lost by the magnesium atom. These electrons, which are called valence electrons, come from magnesium's outermost energy level. As you can see, magnesium has its outermost electrons located on the third energy level, n=3 .