text: Formula:  or 
  * Density: 0.180 kg/m at STP (0 °C, 101325 Pa).
  * Atomic weight: 2.0141017926 Da.
  * Mean abundance in ocean water (from VSMOW) 155.76 ± 0.1 atoms of deuterium per million atoms of all isotopes of hydrogen (about 1 atom of in 6420); that is, about 0.015% of all atoms of hydrogen (any isotope)
  Data at approximately 18 K for H (triple point):
  * Density:
  ** Liquid: 162.4 kg/m
  ** Gas: 0.452 kg/m
  * Viscosity: 12.6 μPa·s at 300 K (gas phase)
  * Specific heat capacity at constant pressure c:
  ** Solid: 2950 J/(kg·K)
  ** Gas: 5200 J/(kg·K)