Periodic Table of Elements

Element Hydrogen - H

Comprehensive data on the chemical element Hydrogen is provided on this page; including scores of properties, element names in many languages, most known nuclides of Hydrogen. Common chemical compounds are also provided for many elements. In addition technical terms are linked to their definitions and the menu contains links to related articles that are a great aid in one's studies.

Hydrogen Menu

Overview of Hydrogen

Hydrogen's Name in Other Languages

  • Latin: Hydrogenium
  • Czech: Vodík
  • Croatian: Vodik
  • French: Hydrogéne
  • German: Wasserstoft - r
  • Italian: Idrogeno
  • Norwegian: Hydrogen
  • Portuguese: Hidrogênio
  • Russian: Водород
  • Spanish: Hidrógeno
  • Swedish: Väte

Atomic Structure of Hydrogen

Chemical Properties of Hydrogen

Physical Properties of Hydrogen

  • Atomic Mass Average: 1.00794
  • Boiling Point: 20.418K -252.732°C -422.918°F
  • Coefficient of lineal thermal expansion/K-1: N/A
  • Conductivity
    Thermal: 0.001815 W/cmK
  • Density: 0.0899g/L @ 273K & 1atm
  • Description:
    Tasteless, colorless, odorless and extremely flammable gas.
  • Enthalpy of Atomization: 217.6 kJ/mole @ 25°C
  • Enthalpy of Fusion: 0.059 kJ/mole
  • Enthalpy of Vaporization: 0.449 kJ/mole
  • Flammablity Class: Highly flammable gas
    • Auto Ignition Temp: 773K 500°C 932°F
    • Explosive Limits
      Lower (LEL): 17%
      Upper (UEL): 56%
    • Flammable Limits
      Lower (LFL): 4%
      Upper (UFL): 75%
    • Flash Point: 20K -253°C -423°F
      Theoretical (there are no oxidizing materials i.e. oxygen in the gas state at this temperature, which is necessary to support combustion.)
  • Freezing Point: see melting point
  • Heat of Vaporization: 0.44936kJ/mol
  • Melting Point: 14.175K -258.975°C -434°F
  • Molar Volume: 14.1 cm3/mole
  • Optical Refractive Index: 1.000132 (gas) 1.12 (liquid)
  • Physical State (at 20°C & 1atm): Gas
  • Realitive Gas Density (Air=1) = 0.0694
  • Specific Heat: 14.304J/gK
  • Vapor Pressure = 1570mmHg@-250°C

Regulatory / Health

  • CAS Number
    • 1333-74-0 Compressed gas
  • UN/NA ID and ERG Guide Number
    • UN1049  / 115 Compressed gas
    • UN1966  / 115 Refrigerated liquid
  • RTECS: MW8900000
  • NFPA 704
    • Health: 1
    • Fire: 4
    • Reactivity: 0
    • Special Hazard:
  • OSHA Permissible Exposure Limit (PEL)
    • No limits set by OSHA
  • OSHA PEL Vacated 1989
    • No limits set by OSHA
  • NIOSH Recommended Exposure Limit (REL)
    • No limits set by NIOSH
  • Levels In Humans:
    Note: this data represents naturally occuring levels of elements in the typical human, it DOES NOT represent recommended daily allowances.
    • Blood/mg dm-3: n/a
    • Bone/p.p.m: n/a
    • Liver/p.p.m: n/a
    • Muscle/p.p.m: n/a
    • Daily Dietary Intake: n/a
    • Total Mass In Avg. 70kg human: n/a

Who / Where / When / How

  • Discoverer: Henry Cavendish
  • Discovery Location: London England
  • Discovery Year: 1766
  • Name Origin:
    Greek: hydro (water) and genes (generate)
  • Abundance of Hydrogen:
    • Earth's Crust/p.p.m.: N/A
    • Seawater/p.p.m.: N/A
    • Atmosphere/p.p.m.: N/A
    • Sun (Relative to H=1E12): 73
  • Sources of Hydrogen:
    Found chiefly combined with oxygen in the form of water, also found in mines and oil & gas wells. Stars contain a virtually unlimited supply hydrogen and in the universe, hydrogen is the most abundant element (hydrogen makes up 73% of the mass of the visible universe). Annual world production of hydrogen is around 350,000,000,000 cubic meters.
  • Uses of Hydrogen:
    Hydrogen's uses include: being used in the production of ammonia, ethanol, hydrogen chloride and hydrogen bromide; the hydrogenation of vegetable oils; hydrocracking, hydroforming and hydrofining of petroleum; atomic-hydrogen welding; instrument-carrying ballons; fuel in rockets; and cryogenic research. Its two heavier isotopes, deuterium (D) and tritium (T), are used respectively for nuclear fission and fusion. Also used in fuel cells for electric cars and other electric machines/devices.
  • Additional Notes:

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A list of reference sources used to compile the data provided on our periodic table of elements can be found on the main periodic table page.

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