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

Hydrogen's single 1s^1 electron gives it a dual character — resembling alkali metals in one way and halogens in another — so it cannot be firmly placed in either Group 1 or Group 17.

Electronic configuration of hydrogen

Hydrogen has the electronic configuration 1s^1 — a single electron in its only (first) shell.

Resemblance to alkali metals (Group 1)

Like the alkali metals, which have the general configuration ns^1, hydrogen has one electron in its outermost (and only) shell. Like them, it can lose this one electron to form a unipositive ion, H+, and combines with halogens to form ionic-like halides (HX), similar to how alkali metals (M) form MX halides. On this basis, hydrogen is placed above Group 1 (Li, Na, K, ...) in many periodic tables.

Resemblance to halogens (Group 17)

Hydrogen's single electron also makes it just one electron short of the stable, fully-filled duplet configuration of helium (1s^2) — directly analogous to how halogens (ns^2np^5) are one electron short of a stable noble-gas octet. On this basis, hydrogen, like the halogens, can gain one electron to form a uninegative hydride ion, H^-, and exists as a diatomic molecule (H2), just as halogens exist as diatomic molecules (Cl2, Br2, etc.). On this basis, hydrogen is sometimes placed above Group 17 (F, Cl, Br, ...).

Conclusion — anomalous position …