Mg=Magnesium
Since the Atomic number is 12, then the number of protons it has is 12
The atomic mass (the bigger of the two numbers shown on a periodic table) is the number of protons + the number of neutrons
So Mg's Atomic mass is about 24 amu
Therefore 24-(12 protons)=12 Neutrons
Since the Atomic number is 12, then the number of protons it has is 12
The atomic mass (the bigger of the two numbers shown on a periodic table) is the number of protons + the number of neutrons
So Mg's Atomic mass is about 24 amu
Therefore 24-(12 protons)=12 Neutrons