What is Isotopes of hydrogen?
[[File:Protium deuterium tritium.jpg|right|thumb|The three most stable isotopes of hydrogen]] '''Hydrogen''' has three main '''[[isotope]]s'''; [[protium]] (<sup>1</sup>H), [[deuterium]] (<sup>2</sup>H) and [[tritium]] (<sup>3</sup>H). These isotopes form naturally in nature. Protium and deuterium are stable. Tritium is [[radioactivity|radioactive]] and has a [[half-life (element)|half-life]] of about 12 years. Scientists have created four other hydrogen isotopes (<sup>4</sup>H to <sup>7</sup>H), but these isotopes are very unstable and do not exist naturally. The main isotopes of hydrogen are unique because they are the only isotopes that have a name. These names are still in use today. Deuterium and tritium sometimes get their own symbols, D and T. However, the [[International Union of Pure and Applied Chemistry]] does not like these names much, even though they are often used. There are other isotopes that had their own names when scientists studied radioactivity. But, their names are no longer used today. == Protium (hydrogen1) == {{further|hydrogen atom}} [[File:Hydrogen.svg|thumb|right|200px|Protium, the most common isotope of hydrogen. It is special because it is the only isotope that has no neutron.]] Protium is the most common isotope of hydrogen. It makes up more than 99.98% of all the hydrogen in the universe. It is named ''protium'' because it's [[atomic nucleus|nucleus]] only has one [[proton]]. Protium has an atomic mass of 1.00782504(7)&nbsp;[[atomic mass unit|u]]. The symbol for protium is '''<sup>1</sup>H'''. The proton of protium has never [[radioactive decay|decayed]] in an observation, so scientists believe that protium is a stable isotope. New theories of [[particle physics]] predict that [[proton decay|a proton can decay]], but this decay is very slow. The proton is said to have a half-life of 10<sup>36</sup> years. If proton decay is true, then all other nuclei that are said to be stable are actually only ''observationally stable'', i.e. they look like they are stable. Recent experiments