Hydrogen is the element of the 1st group and 1st period of the periodic table as it is the simplest element with one electron and one proton inside its atom. It’s found in diatomic form(having two atoms of Hydrogen in one molecule).
Dihydrogen is the most abundant element in the universe and the mass of total Hydrogen present in the universe is 70% of the mass of whole universe.
Isotopes of Hydrogen: Hydrogen has three isotopes. As follows:
I. Protium : It is the most common form of hydrogen atoms. In this form a hydrogen atom has one electron and one proton.
II. Deuterium : It is the second common form which contains one electron and two protons.
III. Tritium : It is a radioactive form. Its half life is 12.33 years.