| − | Tritium is an [isotope] of [hydrogen], with a [nucleus] composed of a [proton] and two [neutrons]. It is very rare on [Earth], as it is only naturally produced by [cosmic rays], and decays into helium-3. | + | Tritium is an [[isotope]] of ][hydrogen]], with a [[nucleus]] composed of a [[proton]] and two [[neutrons]]. It is very rare on [[Earth]], as it is only naturally produced by [[cosmic rays]], and decays into helium-3. |