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Chemical Symbol             : H
Atomic number                : 1
Atomic mass                     : 1.008 amu in C-12 scale
electronic configuration : 1s1
Valency                              : 1
Greek: Hydro-water, genas-produce i.e. water producer

⁕ Occurrence

↪ Hydrogen was discovered by Henry Cavendish in 1766 as a distinct substance (element).
↪ Lavoisier in 1783 gave the name hydrogen (water producer).

↪ Hydrogen is present in the Earth’s crust in water and hydrocarbons, other organic matters and clay.
↪ Hydrogen constitutes about 0.9% by mass of the earth’s crust and it is placed 9th in order of abundance.
↪ Industrial and natural reactions set by hydrogen in the atmospheric in free diatomic gaseous molecular state but it is present only to the extent of 1 part in a million parts by volume.
↪ This extreme low abundance despite of these continuous production is due to the molecular speed of hydrogen at atmospheric temperature is so high that it is escaped continuously from the earth’s gravitational field.

 Position of Hydrogen in periodic table

↪ Hydrogen is the lightest known element in the periodic table.
↪ Primarily, it shows the properties of nonmetal rather than a metal.
↪ Hydrogen is found to show similarities as well as dissimilarities with alkali and halogens however it is placed in group 1 with alkali metals due the common valence shell electronic configuration (ns1) for them.

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