Name : Hydrogen

Symbol : H

Atomic number : 1

Standard atomic weight 1,008

Ionization energy Kj/mol : 1312

Electronegativity Pauling : 2,20

Density g/l @ 0°C 1atm : 0,0899

Oxidation number : 

Electronic configuration :

Position in the periodic table : group 1 - s-block - period 1

Discovery : Henry Cavendish 1776.

Named by : Antoine Lavoisier 1783.


Hydrogen is a colorless, odorless gas, is not poisonous. In the gaseous state is a very good fuel. It is the lightest and the most abudant element of the Universe.

The earth's surface produces it continually in volcanic emanations, in fumarols, in oil sources  but it is dispersed in space considering that it is 14 times lighter than the air.

Hydrogen is present, combined with other elements, in many compounds such as water, mineral substances, hydrocarbons and biological molecules.

It can be obtained from fossil fuels, water, or biomass.
Hydrogen gas production occurs through subsequent refining and fractionation stages of hydrocarbon molecules until complete carbon elimination.

To extract hydrogen from petroleum or methane is used water vapor at 800 degrees Celsius in the presence of a catalyst, this operation is called reforming.
Another system for producing hydrogen is the cracking that consists of the breakdown of the methane molecule by thermal systems.

To obtain hydrogen from coal, a gasification process must be carried out: the coal is reacted with water vapor at 900 degrees centigrade and then at 500 degrees centigrade with another catalyst compound. The resulting gas, formed of hydrogen and carbon monoxide, was once used as city gas.


Hydrogen can be used as fuel to produce energy or to produce other compounds.
In the chemical industry it is used to produce ammonia, methyl alcohol (methanol), fertilizers for agriculture and petroleum products. In the metalworking industry it is used for the treatment of metals.
Hydrogen is a fuel that can be used to produce energy in two ways. The first method is to burn hydrogen alone or add to other fuels. The second method consists of obtaining directly electrical energy through a device called a fuel cell.

Hydrogen combustion produces much less polluting emissions than other fuels. Combustion products are water, unburnt hydrogen and traces of ammonia. So if the engines were powered with this gas, it could produce energy by avoiding harmful emissions.
Hydrogen can be used in cars fuel cells.