Back to Elements List Hydrogen was recognized as a distinct substance by Henry Cavendish in 1776. Diagram of a simple hydrogen atom. Hydrogen Atomic Number: 1 Atomic Radius: 110 pm (Van der Waals) Atomic Symbol: H Melting Point: -259.34 °C Atomic Weight: 1.008 Boiling Point: -252.87 °C Electron Configuration: 1s 1 Oxidation States: 1, -1 History From the Greek word hydro (water), and genes (forming). Hydrogen was recognized as a distinct substance by Henry Cavendish in 1776. Diagram of a simple hydrogen atom. Hydrogen is the most abundant of all elements in the universe. The heavier elements were originally made from hydrogen atoms or from other elements that were originally made from hydrogen atoms. Sources Hydrogen is estimated to make up more than 90% of all the atoms -- three quarters of the mass of the universe!...