Magnesium contains 12 protons. The number of protons of an element determines the atomic number on the periodic chart. The atomic number, or number of protons, is located in the top left corner of the element box, while the atomic weight is located underneath the element's symbol or name.
Magnesium is found in the third period of group II on the periodic table. Magnesium (Mg) is an alkali earth metal with 12 protons, 12 neutrons and 12 electrons. As a metal, magnesium is silvery in color, conducts electricity, is flammable, is solid at room temperature and is reactive to water. Magnesium is abundant both on Earth and within the human body.