RE:RE:RE:RE:RE:RE:RE:RE:RE:RE:RE:RE:RE:RE:BATTERY THAT DOES NOT NEED TO CHARGE!!!! Hydrogen is the chemical element with the symbol H and atomic number 1. With a standard atomic weight of 1.008, hydrogen is the lightest element in the periodic table. Hydrogen is the most abundant chemical substance in the universe, constituting roughly 75% of all baryonic mass.