# Question #47128

Mar 11, 2017

There are $12$ protons and $10$ electrons in a ${\text{Mg}}^{2 +}$ ion, the normal amount of neutrons is $12$.

#### Explanation:

Magnesium is an element with atomic number $12$. This means that every magnesium atom will have $12$ protons.

In a magnesium atom, there are $12$ electrons, to make the atom have a neutral charge. When an ion is formed, the magnesium atom loses electrons. The $2 +$ charge shows that the magnesium ion has two more protons than electrons. The proton number for magnesium does not change, so ${\text{Mg}}^{2 +}$ must have two less electrons, i.e. $10$ electrons.

The number of neutrons varies among different isotopes of magnesium. An isotope of an element means it just has different amounts of neutrons.

The most common isotope of magnesium is $\text{^24"Mg}$. This $24$ indicates the total number of protons and neutrons. Magnesium has $12$ protons, so must have

$24 - 12 = \text{12 neutrons}$

Other isotopes of magnesium have different numbers of neutrons, i.e. $\text{^25"Mg}$ has $13$ neutrons, $\text{^26"Mg}$ has $14$ neutrons. $\text{^24"Mg}$ is most likely being referred to in the question, though.

I hope this helped!