Hydrogen atoms have a neutral charge, containing a single proton with a positive charge and a single electron with a negative charge. Unlike all other elements, hydrogen atoms contain no neutrons.
The term "atomic hydrogen" refers to single, unbonded atoms of hydrogen. Atomic hydrogen makes up 75 percent of the mass in the universe. On Earth, hydrogen is typically found in a diatomic state, meaning that two hydrogen atoms are bonded together. Diatomic hydrogen is expressed by the molecular formula H2. Bonded hydrogen only disassociates at extremely high temperatures, with the disassociation rate at 4,940 degrees Fahrenheit at 7.85 percent.