Atomic number Element Mass (kg) 45.2 8 oxygen carbon 12.6 6 hydrogen 7.0 1 2.2 7 nitrogen calcium 1.3 20 15 0.78 phosphorus 0.25 19 potassium 16 sulfur 0.18 others 0.60 total 70.0 Potassium makes up what fraction of the mass of the human body? Potassium makes up what percentage of the mass of the human body? % What is the mass of phosphorus in a 19 kg person? kg