hydrogen (H) /hī″drəjən/ [Gk, hydor + genein, to produce] , a gaseous monovalent element. Its atomic number is 1; its atomic mass is 1.008. It is the simplest and the lightest of the elements and is a colorless, odorless, highly flammable diatomic gas. It occurs in pure form only sparsely in the earth and the atmosphere but is plentiful in the sun and in many other stars. Hydrogen is a component of numerous compounds, many of them produced by the body. As a component of water, hydrogen is crucial in the metabolic interaction of acids, bases, and salts within the body and in the fluid balance necessary for the body to survive.
