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Hydrogen and its compounds
Hydrogen is the lightest element and also the lightest gas in the periodic table.
It is the lightest non-metal. It is the simplest element in periodic table having only 1e,
1p & no neutron.
Electronic configuration of H is 1s1
Number of e = 1
Number of shells = 1
Number of orbital = 1
Number of subshell =1
It is discovered by Henry Cavendish & it was called inflammable element.
The name hydrogen was given by Lavoisier
Hydrogen
Hydro (Water)
Gene (Producer) or generator
means according to Lavoisier the gas which produce water on burning with oxygen.
1
H + O H O
2
2
2 2
Order of Abundance of H :
Hydrogen is the most abundant element in the universe (70% of the total mass of the universe.)
Order of abundance of H :
Universe > Sun atm > Earth
The planet Jupiter & Saturn consist mainly of H
2
. Similarly about half the mass of the sun & some other stars is
made up of hydrogen.
In Sun's atomsphere & in universe, It is found in atomic form. While in earth it is generally found in molecular
form. At Sun, the stratosphere is made up of H (atomic hydrogen) & they undergoes fusion & converted into He
nuclei & this reaction is exothermic so lot of amount of energy is liberated.
It is the ninth element on earth in order of abundance.
Earth does not posses enough gravitational force to retain live hydrogen molecule i.e. why it is not found in earth
atomosphere in atomic form.
Hydrogen is the most reactive elements in atomic form but it is less reactive in molecular form because of very
high bond dissociation energy due to 1s -1s overlapping.
2 . POSITION OF H
2
IN PERIODIC TA BLE :
Hydrogen is the first element of Periodic table but still it could not be assigned a proper position either in
Mendeleef periodic table or in Modern periodic table because of following reasons.
It may kept in<