Question

Why is Hydrogen placed in group $I$ of the modern periodic table ?

Answer 1

Hydrogen is placed in group $I$ of the modern periodic table due to following reasons:-

$\left(1\right)$ It shows outer electronic configuration similar to group $I$ elements (i.e.$1s^1$).

$\left(2\right)$ It readily looses its electron to form $H^{+}$ ion which resembles the electropositive character of group $I$ elements.

$\left(3\right)$ It shows $+1$ oxidation state like alkali i.e. group $I$ elements.

$\left(4\right)$ Hydrogen also acts as a strong reducing agent like alkali metals and also forms binary compounds with electronegative elements which resembles the group $I$ elements.