How Many Atoms There Are in the Human Body

How Many Atoms There Are in the Human Body Have you ever wondered how many atoms are in the human body? Heres the calculation and answer to the question. Short Answer There are approximately 7 x 1027 atoms in the average human body. This is the estimate for a 70 kg adult human male. Generally, a smaller person would contain fewer atoms; a larger person would contain more atoms. Atoms in the Body On average, 87 percent of the atoms in the body are hydrogen or oxygen. Carbon, hydrogen, nitrogen, and oxygen together account for 99 percent of the atoms in a person. There are 41 chemical elements found in most people. The exact number of atoms of the trace elements varies widely according to age, diet, and environmental factors. Some of these elements are needed for chemical processes in the body, but others (e.g., lead, uranium, radium) have no known function or are toxic contaminants. Low levels of these elements are a natural part of the environment and typically do not cause health problems. In addition to the elements listed in the table, additional trace elements may be found in some individuals. Reference: Freitas, Robert A., Jr., Nanomedicine, foresight.org/Nanomedicine/index.html, 2006. Atomic Composition of a Lean 70-kg Man Element # of Atoms hydrogen 4.22 x 1027 oxygen 1.61 x 1027 carbon 8.03 x 1026 nitrogen 3.9 x 1025 calcium 1.6 x 1025 phosphorus 9.6 x 1024 sulfur 2.6 x 1024 sodium 2.5 x 1024 potassium 2.2 x 1024 chlorine 1.6 x 1024 magnesium 4.7 x 1023 silicon 3.9 x 1023 fluorine 8.3 x 1022 iron 4.5 x 1022 zinc 2.1 x 1022 rubidium 2.2 x 1021 strontium 2.2 x 1021 bromine 2 x 1021 aluminum 1 x 1021 copper 7 x 1020 lead 3 x 1020 cadmium 3 x 1020 boron 2 x 1020 manganese 1 x 1020 nickel 1 x 1020 lithium 1 x 1020 barium 8 x 1019 iodine 5 x 1019 tin 4 x 1019 gold 2 x 1019 zirconium 2 x 1019 cobalt 2 x 1019 cesium 7 x 1018 mercury 6 x 1018 arsenic 6 x 1018 chromium 6 x 1018 molybdenum 3 x 1018 selenium 3 x 1018 beryllium 3 x 1018 vanadium 8 x 1017 uranium 2 x 1017 radium 8 x 1010