Hydrogen is a non-metal. Hydrogen is a colourless, odourless and tasteless gas that is the most abundant element in the known universe. It is the lightest and simplest having only one proton and one electron. Although hydrogen has ns1 electron configuration just like alkali metals, it is still not a metal because it varies greatly from the alkali metals as it forms cations (H+) more reluctantly than other alkali metals. Because hydrogen is a nonmetal and forms H–(hydride anions), it is placed above the halogens in the periodic table. Hydrogen also forms H2dihydrogen like halogens. However, hydrogen is very different from the halogens. Hydrogen has a much smaller electron affinity than the halogens.