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Element Abundances

Within a Human
By moles/atoms

  1. Hydrogen - 63%
  2. Oxygen - 25.5%
  3. Carbon - 9.5%
  4. Nitrogen - 1.5%

Per million atoms in the body
26 elements essential to health/well-being of humans

Microminerals: V, Cr, Mo, Mn, Fe, Co, Ni, Cu, Zn, Se, F, I
Essential for animals and likely for humans: B, Si, As
Macrominerals are those present in quantities greater than .08g (80mg) per kilogram of body weight. Microminerals are present in smaller amounts. Ex: daily total intake of iodine is only 150micrograms. Selenium toxic in high concentrations - essential in 55-70micrograms/day.

In Dry Air at Sea Level (the Troposphere)
By moles/atoms

  1. Nitrogen - 78.084%
  2. Oxygen - 20.948%
  3. Argon - .934%
  4. Carbon dioxide - 330ppm, or .033%
  5. Neon - 18.2ppm
  6. Hydrogen - 10ppm
  7. Helium - 5.2ppm
  8. Methane - 2ppm
  9. Krypton - 1ppm
  10. Carbon monoxide - .1ppm
  11. Xenon - .08ppm
  12. Ozone - .02ppm
  13. Ammonia - .01ppm
  14. Nitrogen dioxide - 1ppb, or .001ppm
  15. Sulfur dioxide - .2ppb, or .0002ppm, or .00000002%
Note: "ppm," or parts per million, in this case means simply that for every million air molecules, that many are whatever [ex: hydrogen is 10ppm, so in a million air molecules, ten are hydrogen]. To get from percent to parts per million, simply multiply by 10,000. Ppb is simply parts per billion; multiply ppm by 1,000.

Oxygen most abundant, silicon second, more cerium than copper, neodymium and lanthanum than cobalt or nitrogen, tin barely in top 50 passed by praseodymium, samarium, gadolinium and dysprosium. Aluminum fourth most common, 1/10 of everything under feet, presence not suspected until Humphry Davy discovered it in last 19th century. Carbon 15th most common, .048% of crust. Others: need iron to make hemoglobin, cobalt for making vitamin B12, potassium and sodium lit "good for your nerves," molybdenum, manganese, vanadium keep enzymes going, zinc oxidizeis alcohol, selenium is vital but bit too much is deadly. Degree to which you and other organisms require/tolerate elements is relic of evolution, ex cattle need lots copper [from Europe/africa where lots copper] vs sheep evolved in copper-poor asia minor. Our tolerance directly proportionate to their abundance in Earth's crust.

The Chemical World: Concepts and Applications, Second Edition. Moore, Stanitski, Wood, Kotz. Pages 106, 614.
Bill Bryson's A Short History of Nearly Everything, pages 250-252.

Cosmochemical Periodic Table (.pdf file)