9.1 Justify the position of hydrogen in the periodic table on the basis of its electronic configuration
The electronic configuration of the H atom is . Due to the presence of only one electron, it exhibits dual behaviour,i.e., it resembles both alkali metals of group 1 and also along with the halogens of group 17.
It can lose one electron to form a unipositive ion. Both H and alkali metals form monovalent cations by losing one electron from its outer shell. Both alkali and hydrogen shows +1 oxidation numbers.both have an affinity towards electronegative elements and readily combine with them and forms oxide, halides, and sulphides.
It has a very high ionization enthalpy and does not possess metallic characteristics under normal conditions. In fact, in terms of ionization enthalpy, hydrogen resembles more with halogens, ionization enthalpy of Li is 520 kJ mol–1, F is 1680 kJ mol–1 and that of H is 1312 kJ mol–1. Like halogens, it forms a diatomic molecule, combines with elements to form hydrides and a large number of covalent compounds.