Is hydrogen a nonmetal or a metal?

Hydrogen is a nonmetal.

Hydrogen is in Group 1 of , because it has the same ##ns^1## as the alkali metals.

However, hydrogen differs from metals in several ways.

1. It is reluctant to form cations.

The alkali metals lose electrons easily to form cations.

But the of hydrogen is 2.5 times that of lithium, the alkali metal with the highest ionization energy.

2. Elemental hydrogen consists of ##"H"_2## molecules.

Hydrogen atoms join by covalent bonds to form ##"H"_2## molecules.

The molecules are attracted to each other by weak London dispersion forces.

Metal atoms are attracted to each other by metallic bonds.

Molecules like ##"Na"_2## are so rare that they have been detected only by spectroscopic methods,

3. Hydrogen forms .

The ##"H-Cl"## bond in hydrogen chloride is covalent.

Sodium chloride consists of ##"Na"^+## ions and ##"Cl"^-## ions.

4. Hydrogen forms hydride ions.

Hydrogen forms like ##"NaH"##, ##"KH"##, and ##"CaH"_2##.

In these compounds, the hydrogen exists as the hydride ion, ##"H"^-##.

Compounds containing ##"Na"^"-"## and ##"K"^"-"## ions are rare.

However

Theoretical calculations predict that hydrogen can behave like a metal at a pressure of 500 000 atm.

It may exist as a metal in the interiors of large planets like Jupiter and Saturn.