• Hydrogen, chemical element that exists as a gas at room
temperature. When hydrogen gas burns in air, it forms
water. French chemist Antoine Lavoisier named
hydrogen from the Greek words for "water former."
• Hydrogen has the smallest atoms of any element. A
hydrogen atom contains one proton, and only one
electron . The proton is the center, or nucleus, of the
hydrogen atom, and the electron travels around the
nucleus.
• Pure hydrogen exists as hydrogen gas, in which pairs of
hydrogen atoms bond together to make molecules.