| H | Hydrogen | Atomic number : 1 Relative atomic mass (12C = 12.0000) : 1.00794 |
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| P H Y S I C A L D A T A | |
| Group 1 gas Density / kg m-3 : 76.0 [s., 11 K]; 70.8 [liq., b.p.]; 0.08988 [gas, 273 K] |
Melting point / K : 14.01 Boiling point / K : 20.28 |
| D I S C O V E R Y | |
| Recognized as an element in 1766 by H. Cavendish at London, England. |
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| G E O L O G I C A L D A T A | |
| Abundances Sun (relative to H = 1 × 1012) : most abundant element, and taken as standard against which others are measured. Earth's crust / p.p.m. : 1520 Atmosphere / p.p.m. (volume) : 0.5 Residence time / years : n.a. Oxidation state : I |
Seawater / p.p.m. : constituent of water; some dissolved H2 gas. |
| B I O L O G I C A L D A T A | |
| Level in humans Blood / mg dm-3 : constituent of water Bone / p.p.m. : 52 000 Liver / p.p.m. : 93 000 Muscle / p.p.m. : 93 000 |
Daily dietary intake : mainly as water Total mass of element in average (70 kg) person : 7 kg |
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A portrait of hydrogen is available on the Visual Elements site. Up to 200 individual items of information on this element are available in The Elements. |