09-15-2021-0418 - Hydrogen-1 (Protium)

Hydrogen-1 (Protium)[edit]

Protium, the most common isotopeof hydrogen, consists of one proton and one electron. Unique among all stable isotopes, it has no neutrons. (see diproton for a discussion of why others do not exist)

Main article: Hydrogen atom

¹H (atomic mass 1.007825031898(14) Da) is the most common hydrogen isotope with an abundance of more than 99.98%. Because the nucleus of this isotope consists of only a single proton, it is given the formal name protium.

The proton has never been observed to decay, and hydrogen-1 is therefore considered a stable isotope. Some grand unified theories proposed in the 1970s predict that proton decaycan occur with a half-life between 10²⁸ and 10³⁶ years.^[11] If this prediction is found to be true, then hydrogen-1 (and indeed all nuclei now believed to be stable) are only observationally stable. To date, experiments have shown that the minimum proton half-life is in excess of 10³⁴ years. 

https://en.wikipedia.org/wiki/Isotopes_of_hydrogen#Hydrogen-1_(Protium)