Electronic configuration of hydrogen is 1s1 which is similar to the outer electronic configuration of alkali metals of group 1 i.e., ns1.However, 1s1 also resembles the outer electronic configuration of group 17 elements i.e., ns2 np5.By adding one electron to H, it will attain electronic configuration of the inert gas He which is 1s2 and by adding one electron to ns2 np5 we get ns2 np6 which is the outer electronic configuration of the remaining inert gases. Therefore, some chemical properties of hydrogen are similar to those of alkali metals while some resemble halogens.
Hence, hydrogen shows similarity with alkali metals as well as halogens.
