Chemistry - Hydrogen


  • In the periodic table, hydrogen is the lightest element, its atomic weight is merely 1.008.

  • The symbol of hydrogen is ‘H’ and the atomic number is ‘1.’

  • In the early 16th century, hydrogen gas was first artificially produced by the reaction of acids and metals.

  • Henry Cavendish first recognized the hydrogen gas a discrete substance during the period of 1766-81, as it produces water when it is burned.

Salient Features of Hydrogen

  • In their plasma state, the non-remnant stars are primarily composed of hydrogen.

  • At standard temperature and pressure, hydrogen appears colorless, tasteless, odorless, nonmetallic, non-toxic, and highly combustible diatomic gas.

  • The molecular formula of hydrogen is H2.

  • On the earth, hydrogen exists in molecular forms, for example, water or other organic compounds.

  • Hydrogen also plays an important role in acid–base reactions.

  • Hydrogen gas is highly flammable in the air.

  • Pure hydrogen-oxygen flames radiate ultraviolet light; further, with high oxygen mix are nearly invisible to the naked eye.

  • Hydrogen can react with almost every oxidizing element.

  • At room temperature, Hydrogen normally reacts spontaneously and viciously with chlorine and fluorine and forms the corresponding hydrogen halides.

Occurrence of Hydrogen

  • Consisting roughly about 75 percent of all baryonic mass, hydrogen is the most abundantly found chemical subsistence in the universe.

  • Throughout the universe, hydrogen is typically found in the atomic and plasma states; however, the properties quite different from those of the molecular hydrogen.

  • On the earth, hydrogen exists as the diatomic gas, i.e. H2.

  • Because of having light weight, hydrogen easily escapes from the earth’s atmosphere.

  • Hydrogen is the third most abundant element found on the Earth's surface, but largely found in form of hydrocarbons and water.

Compounds of Hydrogen

  • Following are the major compounds of hydrogen −

    • Water - H2O

    • Ammonia - NH3

    • Hydrogen chloride - HCl

    • Hydrogen fluoride - HF

    • Hydrogen sulfide - H2S

    • Methane - CH4

    • Hydroxide - OH-

    • Hydrogen bromide - HBr

    • Hydrogen iodide - HI

    • Hydrogen cyanide - HCN

    • Phosphine - PH3

    • Hydrogen selenide - H2Se

    • Methanol - CH3OH

    • Lithium hydride - LiH

    • Bicarbonate - HCO3

    • Hydrogen telluride - H2Te

    • Liquid hydrogen - H2

    • Cyanide - CN

    • Calcium hydride - CaH2

    • Heavy water - D2O

    • Diborane - B2H6

    • Sodium hydride - NaH

    • Potassium hydride - KH

Uses of Hydrogen

  • The largest amount of H2 is used in the processing of fossil fuels as well as in the production of ammonia.

  • Hydrogen (H2) is extensively used in the petroleum and chemical industries.

  • H2 is typically used as a hydrogenating agent, especially in increasing the saturation level of unsaturated fats and oils.

  • H2 is also used as a shielding gas in welding procedures, such as atomic hydrogen welding, etc.