Do you know the main component of sun or stars? its HYDROGEN. Hydrogen is an element, exists naturally as molecule. Two hydrogen atoms combined together to form a hydrogen molecule; that is why its chemical formula is H2 and have one proton and one electron. It’s plentiful in the universe but hard to get in natural state on earth.

Nature of Hydrogen gas is:

  • Very Light 
  • Odourless
  • Non-toxic
  • Highly flammable
  • Colourless
  • Tasteless
  • Non corrosive 


The alchemist Paracelsus, in early 1500s, found that when sulphuric acid was added with iron fillings, it produced bubbles which were combustible in nature. Robert Boyle, in 1671, observed the same thing. But both of them, never put in effect their finding of hydrogen.

  Fe + H2SO4 ???? Fe SO+ H2

In 1766, Henry Cavendish, collected these bubbles and proved its distinction from other gases. Later, he proved that water is the main element in it. After the evidence of water, Antoine Lavoisier gave the name “HYDROGEN”, derived from Greek words, hydro means “water” and genes means “former”, means “water-former”. 

Our body has 65% of water and 71% of earth is covered with it. So, water becomes an important component for life. H2O is the chemical formula of it, where two hydrogen atoms with one oxygen atom form a single molecule of water. 

2H2 + O2 ???? 2H2O

In water, strong hydrogen bonds are present. Hydrogen bond is special type of dipole-dipole attraction between molecules. It’s strength range is from 4kJ to 50kJ hydrogen atom per mole.


When atoms have same atomic number but different mass number known as Isotopes. Protium, Tritium, Deuterium are the isotopes of hydrogen.

Protium(1H) is the common isotope, found in abundance in nature. It has only one proton and is decaying.

Deuterium(2H) has one proton and one neutron in its nucleus and non-radioactive in nature. Heavy water is the example of it. NMR spectroscopy, Nuclear weapons, etc are the applications.

Tritium(3H) consists of one proton and two neutrons. It produces cosmic rays when comes in contact with atmospheric gases. Its nature is radioactive. Neutron Initiator, ocean transient tracer, hydrogen bomb, nuclear weapons are few fields of application.


Hydrogen is the smallest element that hardly exist in pure form as it is very combustible and reactive in nature. Some other physical properties are:

  • State: Its boiling point is 20 K(-423 0F, -253 0C) and melting point is 14 K(-434 0F, -259 0C).
  • Taste, Odor, Color: Pure hydrogen has no taste, odor and color and almost invisible in daylight.
  • Toxicity: Its non-toxic in nature.
  • Density: its density in gaseous form is 0.090 g/L and liquid density is 0.70 g/L.
  • If your skin comes in contact with liquid hydrogen, skin freezes. 
  • Hydrogen converts into snow-like crystals at high pressure.
  • As it is less dense than air, It is 14.5 times lighter than air.
  • It has weak bond with lattice nodes, and hence, its crystal structure breaks down easily.
  • Covalent radius of hydrogen is 31.5 pm.
  • It can be used as both oxidizing agent and reducing agent.


  • Hydrogen atom has atomic number 1, with atomic weight of 1,00797 g/mol.
  • Hydrogen element symbol is H.
  • Hydrogen molecular formula is H2, having chemical structure H-H, with molecular weight 2.0159, and water solubility 0.0214 cm3g-1 (00C, 1 atm).
  • Auto-ignition temperature is 500-571 0C.
  • It reacts with Halogen to form Hydrogen Halides, HX.

H2 + X2  ???? 2HX where X can be fluorine, chlorine, bromine, Iodine.

Hydrides: Hydrides are of three types.

  1. Ionic hydrides: When electropositive elements of group I and II of modern periodic table, react with Hydrogen, they form ionic Hydrides. They are non-conductive, crystalline, and non volatile in nature when exist in solid form but conduct electricity in liquid state. They used as a reducing reagents or bases and have high melting and boiling point. KH, NaH, etc. are examples.

  2. Covalent hydrides: These hydrides form with p-block elements of modern periodic table. There is a weak vander wall’s force of attraction between covalent molecules. They are volatile in nature with low melting and boiling point. CH4, H2O, etc. are the examples.
  3. Metallic hydrides: When d-block and f-block elements of modern periodic table react with Hydrogen, metallic hydrides form. They are also called interstitial hydrides and are strong reducing agents. E.g. LaH2, CrH3 etc.


  • Hydrogen Energy: Hydrogen energy comes into play when hydrogen and/or hydrogen compounds involves to produce energy. It is an energy carrier. Hydrogen fuel cells are readily available, and environment friendly. It is renewable. It produces very little pollution with no traces of unburnt carbon particles in smoke, which make it clean-burning fuel and first choice to use in generation of electric power. 

  • Green Hydrogen: Green Hydrogen is manufactured from non-fossil fuel and renewable energy sources without emitting pollutant gases during production or combustion. It is easy to store and can be transformed into synthetic gas or electricity for commercial and industrial purposes.
  • It is used as flushing gas in electronic industry and because of low density nature, used in filling balloons.


  • Its liquid hydrogen form used as rocket fuel to fuel spacecraft. Hydrogenation of vegetable oils, vanaspati fat manufacturing, heavy metals’s metallurgical processes are some common usage of Hydrogen or Dihydrogen.

  • It is used to manufacture ammonia, HCl, and methanol where ammonia used in agriculture fertilizer. Hydrogen production from biomass and fossil fuel are same processes.
  • During oil-refining process, it is used to remove organic sulfur from crude oil.
  • It also yields drinkable water as a by-product.
  • In pharmaceuticals, it is used to produce sugar alcohol i.e., sorbitol which is used in adhesive, surfactants, cosmetics etc. Lighter having butane and gas grill having propane are the daily life examples of hydrogen carbon.
  • Rubber, Polymers, Plastics, and other materials use hydrocarbon or hydrogen carbon as a raw material. 
  • Chemistry is full of surprises. So, the surprise is, all forms of hydrogen is not good for life.  Some are dangerous too. Hydrogen sulfide is a colorless, poisonous, and highly flammable gas that can lead to failure of central nervous system. Still no antidote is available for it. Carbon mono oxide is another example of it. Class 12 chemistry students are already much familiar with hydrogen. This blog will enhance your understanding so that you can perform better.

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