See Also: Chemical Elements
Gaseous (see States Of Matter) Element, discovered by Henry Cavendish in 1766. The first element on the Periodic Table, hydrogen is Colorless, odorless, tasteless, slightly soluble in Water, and highly Explosive. The hot flame produced by a mixture of Oxygen and hydrogen is used in welding, and in melting quartz and glass. Normal
hydrogen is diatomic. The most abundant element in the universe, hydrogen is the
major fuel in fusion reactions of the Sun and other Stars. Atmospheric hydrogen has three Isotopes: protium (nucleus: one Proton), the most common; deuterium, or heavy hydrogen (nucleus: one proton and one Neutron), used in Particle Accelerator and as a tracer for studying chemical-reaction mechanisms; and tritium
(nucleus: one proton and two neutrons), a radioactive gas used in the Hydrogen Bomb (see Atomic Bomb), in luminous paints, and as a tracer. Hydrogen's principal use is in the
synthesis of Ammonia; liquid (see States Of Matter) hydrogen has been greatly used as a rocket fuel, in conjunction with oxygen
or fluorine. Deuterium oxide (see Oxidation and Reduction), or heavy water, is used as a moderator in Nuclear Reactors.