Question

Duplet rule for the formation of Hydrogen.

Answer 1

Hint: The stability of the elements present in the periodic table does not only depend on the octet rule which states that for the element to be stable it should contain 8 electrons in their valence shell. Duplet rule is specially employed for the element which only contains s-orbital.

Complete answer:The elements other than hydrogen follow octet rule which says that the element should possess a total eight electrons in its outermost orbital to obtain stability.
Apart from octet rule, there is one other rule especially for hydrogen known as duplet rule which says that the element can attain stability even with two electrons in the valence shell.
A Hydrogen atom has reached its stability by filling its outermost orbital with two electrons. When the element has two electrons in its outermost orbital instead of eight electrons it does not affect the stability of the individual element because it has 1s orbital which can maximum hold two electrons in its shell.
Hydrogen atoms do not follow octet rule because the s-orbital is too small to hold eight electrons and a high energy barrier is maintained by which more electrons are not able to get inside the empty shell.
The atomic number of hydrogen atom is one, so two hydrogen atoms share its one electron each to obtain its duplet state by forming a hydrogen molecule.

Note:
Apart from Hydrogen, Helium is the other element in the periodic table which does not follow octet rule, instead it attains its stability by the duplet rule as it only contains one s- orbital and no p-orbital. It contains two electrons in its s-orbital.