Discuss the position of hydrogen in the periodic table on the basis of its electronic configuration.

Explanation

Hydrogen is the simplest element with one electron and proton. Its electronic configuration is 1s. The configuration is responsible for its dual nature. It behaves both like alkali metals and halogens. So it can be placed along with alkali metals (IA) or along with halogens (VIIA).
Points in support of placing it in IA group :
a) Like alkali metals hydrogen also has a single electron in the outer shell `1s^(1)`.
b) Its ability to form hydrated unipositive ion, `H^(+)` (aq).
c) It is quite reasonable to start the periodic table with an element having the least atomic number (Z = 1).
Points in support of placing it in VIIA group :
a) Hydrogen is a gas like fluorine or chlorine.
b) It can form diatomic, molecule like halogens.
c) It has a tendency of gaining an electron and attains a stable electronic configuration of He forming `H^(-)` ion like halogens.
At the same time it should be noted that hydrogen has not such a great tendency to lose electron like alkali metals and gain an electron like halogens. In view of this it is difficult to assign any definite position to hydrogen. Sometimes it is placed in IA group and sometime with VIIA group.