Question

use isotope notation below to answer this question: how many protons, neutrons, and electrons are in magnesium.

Explanation:

Step1: Identify proton number

The bottom - left number in isotope notation is the atomic number (Z), which is equal to the number of protons. For $\ce{^{25}_{12}Mg^{2 + }}$, the atomic number $Z = 12$, so the number of protons is 12.

Step2: Calculate neutron number

The top - left number in isotope notation is the mass number (A). The mass number $A=25$. The number of neutrons $N$ is calculated by the formula $N=A - Z$. Substituting $A = 25$ and $Z = 12$, we get $N=25 - 12=13$.

Step3: Determine electron number

A neutral magnesium atom has the same number of electrons as protons, which is 12. But this is a $\ce{Mg^{2+}}$ ion, which means it has lost 2 electrons. So the number of electrons is $12-2 = 10$.

Answer:

Protons: 12, Neutrons: 13, Electrons: 10