# What is the electronic configuration of Mg^(2+) ion?

Nov 13, 2017

The electron configuration of the magnesium ion Mg2+ is similar to Na+, Ne, and Al3+. It is not similar to Ar.

#### Explanation:

Okay, so we are given these answer choices, but how do we know which 3 share the same electron configuration as Mg2+?

Before going on, it is important to note that when an element is written as Mg2+, it means that it is losing 2 electrons. How do we know this? Because electrons have a negative charge, and since it has been written as a positive number, that means that instead of gaining electrons and moving to the right, we are going to lose electrons and move to the left.

For example, look at Na (Sodium) and Mg (Magnesium) on the periodic table below. They are right next to each other. If we say Na+, we are losing one electron, therefore going reverse, not forward. Consequently, we would land on Ne, Neon.

If we do the same thing for Mg2+ by going back 2 elements (because it is 2+), we also land on Ne. If we go back three elements for Al3+, we would land on Ne. And, of course, Ne is Neon, so we don't have to do anything to that.

However, Argon does not share the same electron configuration as any of these. Argon is right below Neon on the periodic table since both are Noble Gases. Therefore, there is no way that it is going to gain or lose electrons to have the same configuration as Neon.

Quick side note: elements want to gain/lose electrons in order to be in its most stable state. Na has one electron on its outer most shell (the valence shell), so it wants to lose it by being Na+, or Ne, so that it can be stable. Noble gases are the only elements on the periodic table that have full valence shells.

Hope this helps!