In chemistry, magnesium (LH:12), symbol Mg, the 12th element (Z:12) of the periodic table, is an atom, with a mass of 23.32 amu, comprised of 12 protons, 12 neutrons, and 12 electrons; with an electron configuration of: [Ne] 3s2.
The following is an early estimate of the percent magnesium in humans:
- “The human body contains carbon 13.5%, hydrogen 9.1%, oxygen 72%, nitrogen 2.5%, phosphorus 1.15%, sodium 0.1 %, calcium 1.3%, magnesium 0.001%, iron 0.01%, and traces of silicon and fluorine.”
- — Carl Kelsey (1916), The Physical Basis of Society (pg. 7) 
- Magnesium – Wikipedia.