Question

Why hydrogen is not a metal as it forms positive ion?

Answer 1

Answer:

Hydrogen is one of the most remarkable element known to the mankind. It is the only element in which the valence electrons are in the n=1 shell. As a result, hydrogen can have three oxidation states, which are H+ ion, a neutral H atom, and the H- ion. It shows both metallic and non metallic behaviours according to the physical conditions and it cannot be concluded as a non metal.

It forms compounds (such as HCl and HNO3) that are analogs of alkali metal compounds (such as NaCl and KNO3). Under conditions of very high pressure, it has the properties of a metal. Also hydrogen combines with a handful of metals, such as scandium, titanium, chromium, nickel, or palladium, to form materials that behave as if they were alloys of two metals.

Finally, the element is a gas at room temperature and atmospheric pressure, like other nonmetals (such as O2 & N2).

Checking the other properties such as Ionization energy and electronegativity, The first ionization energy of hydrogen (1312kJ/mol), for example, is roughly halfway between the elements with the largest (2372kJ/mol) and smallest (376kJ/mol) ionization energies. Hydrogen also has an electronegativity (EN = 2.20) halfway between the extremes of the most electronegative (EN = 3.98) and least electronegative (EN = 0.7) elements. On the basis of electronegativity, it is tempting to classify hydrogen as a semimetal.