Question

Hydrogen should be placed in which group and which period ? Give reasons.

Answer 1

The position of hydrogen in the modern periodic table is still a topic of debate. Some people place hydrogen along with alkali metal in group I, while others place hydrogen separately at the top of the table. This is because its configuration resembles the configuration of two different groups - group 1 and group 17. Hydrogen has a single electron in its valence shell. Thus it can lose an electron to achieve a stable configuration like alkali metals and hence can be placed in group 1 (alkali metals). However, it can also gain an electron to achieve a noble gas arrangement and hence can be placed along with group 17 (halogen family) elements. However, it is generally placed along group 1 elements, as it readily forms H+ ions by losing one electron. 

Answer 2

Hydrogen can be placed in either group 1 or group 17 . Hydrogen exhibits properties of both alkali metals such as cation formation ,mono valency and that of halogens such as anion formation , covalent bonding . One cannot comprehensively conclude the exact position of hydrogen in the periodic table and it is hence places away from both groups