Editing Hydrogen atom (section)

==Isotopes==
{{Main|Isotopes of hydrogen}}
The most [[Abundance of the chemical elements|abundant]] [[isotope]], protium (<sup>1</sup>H), or light hydrogen, contains no [[neutron]]s and is simply a [[proton]] and an [[electron]]. Protium is [[Proton decay|stable]] and makes up 99.985% of naturally occurring hydrogen atoms.<ref name="Housecroft">{{cite book |last1=Housecroft |first1=Catherine E. |last2=Sharpe |first2=Alan G. |edition=2nd |date=2005 |title=Inorganic Chemistry |publisher=Pearson Prentice-Hall |page=237 |isbn=0130-39913-2}}</ref>

[[Deuterium]] (<sup>2</sup>H) contains one neutron and one proton in its nucleus. Deuterium is stable, makes up 0.0156% of naturally occurring hydrogen,<ref name="Housecroft" /> and is used in industrial processes like [[nuclear reactor]]s and [[Deuterium NMR|Nuclear Magnetic Resonance]].

[[Tritium]] (<sup>3</sup>H) contains two neutrons and one proton in its nucleus and is not stable, decaying with a [[half-life]] of 12.32 years. Because of its short half-life, tritium does not exist in nature except in trace amounts.

Heavier isotopes of hydrogen are only created artificially in [[particle accelerators]] and have half-lives on the order of 10<sup>−22</sup> seconds. They are unbound [[resonance (particle physics)|resonances]] located beyond the [[neutron drip line]]; this results in prompt [[neutron emission|emission of a neutron]].

The formulas below are valid for all three isotopes of hydrogen, but slightly different values of the [[Rydberg constant]] (correction formula given below) must be used for each hydrogen isotope.