Isotopes of hydrogen#Hydrogen-6

Note: "y" means year, but "ys" means yoctosecond (10{{sup|−24}} second).

{{Isotopes table

|symbol=H

|refs=NUBASE2020, AME2020 II

|notes=mass#, unc(), var[], spin#, spin(), daughter-st, n, note

}}

|-

| {{sup|1}}H

| 1

| 0

| {{val|1.007825031898|(14)}}

| colspan=3 align=center|StableUnless proton decay occurs.This and {{sup|3}}He are the only stable nuclides with more protons than neutrons.

| 1/2+

| colspan="2" style="text-align:center" | [{{val|0.99972}}, {{val|0.99999}}]{{Cite web|title=Atomic Weight of Hydrogen|url=http://ciaaw.org/hydrogen.htm|access-date=24 June 2021|website=CIAAW}}

| Protium

|-

| Deuterium (D)Produced in Big Bang nucleosynthesis.One of the few stable odd-odd nuclei

| 1

| 1

| {{val|2.014101777844|(15)}}

| colspan=3 align=center |Stable

| 1+

| colspan="2" style="text-align:center" | [{{val|0.00001}}, {{val|0.00028}}]

| Deuterium

|-

| Tritium (T){{refn|group=n|Produced in Big Bang nucleosynthesis, but not primordial, as all of it has decayed to {{sup|3}}He.{{cite journal |title=Big-bang nucleosynthesis: A probe of the early Universe |first=Alain |last=Coc |journal=Nuclear Instruments and Methods in Physics Research Section A |volume=611 |issue=2–3 |date=2009 |pages=224–230 |doi=10.1016/j.nima.2009.07.052|bibcode=2009NIMPA.611..224C }}}}

| 1

| 2

| {{val|3.016049281320|(81)}}

| {{val|12.33|(2)|u=y}}

| beta decay

| {{sup|3}}He

| 1/2+

| TraceTritium occurs naturally as a cosmogenic nuclide.

|

| Tritium

|-

| {{sup|4}}H

| 1

| 3

| {{val|4.02643|(11)}}

| {{val|139|(10)|ul=ys}}

| n

| {{sup|3}}H

| 2−

|

|

|-

| {{sup|5}}H

| 1

| 4

| {{val|5.03531|(10)}}

| {{val|86|(6)|u=ys}}

| 2n

| {{sup|3}}H

| (1/2+)

|

|

|-

| {{sup|6}}H

| 1

| 5

| {{val|6.04496|(27)}}

| {{val|294|(67)|u=ys}}

|

|

| 2−#

|

|

|-

| {{sup|7}}H

| 1

| 6

| {{val|7.052750|(108)}}#

| {{val|652|(558)|u=ys}}

|

|

| 1/2+#

|

|

{{Isotopes table/footer}}

File:H-1 atom.png for a discussion of why no others exist)]]{{Redirect|Protium}}

{{sup|1}}H (atomic mass {{val|1.007825031898|(14)|ul=Da}}) is the most common hydrogen isotope, with an abundance of >99.98%. Its nucleus consists of only a single proton, so it has the formal name protium.

The proton has never been observed to decay, so {{sup|1}}H is considered stable. It is the only stable nuclide with no neutrons. Some Grand Unified Theories proposed in the 1970s predict that proton decay can occur with a half-life between {{val|e=28}} and {{val|e=36}} years.{{cite web |title=Grand Unified Theories and Proton Decay |author=Ed Kearns |publisher=Boston University |date=2009 |page=15 |url=http://physics.bu.edu/NEPPSR/TALKS-2009/Kearns_GUTs_ProtonDecay.pdf}} If so, then {{sup|1}}H (and all nuclei now believed to be stable) are only observationally stable. As of 2018, experiments have shown that the mean lifetime of the proton is >{{val|3.6|e=29}} years.{{Cite journal |last1=The SNO+ Collaboration |last2=Anderson |first2=M. |last3=Andringa |first3=S. |last4=Arushanova |first4=E. |last5=Asahi |first5=S. |last6=Askins |first6=M. |last7=Auty |first7=D. J. |last8=Back |first8=A. R. |last9=Barnard |first9=Z. |last10=Barros |first10=N. |last11=Bartlett |first11=D. |date=2019-02-20 |title=Search for invisible modes of nucleon decay in water with the SNO+ detector |journal=Physical Review D |volume=99 |issue=3 |pages=032008 |doi=10.1103/PhysRevD.99.032008 |arxiv=1812.05552 |bibcode=2019PhRvD..99c2008A |s2cid=96457175 |doi-access=free}}

{{Main|Deuterium}}

File:H-2 atom.png

Deuterium, {{sup|2}}H (atomic mass {{val|2.014101777844|(15)|ul=Da}}), the other stable hydrogen isotope, has one proton and one neutron in its nucleus, called a deuteron. {{sup|2}}H comprises 26–184 ppm (by population, not mass) of hydrogen on Earth; the lower number tends to be found in hydrogen gas and higher enrichment (150 ppm) is typical of seawater. Deuterium on Earth has been enriched with respect to its initial concentration in the Big Bang and outer Solar System (≈27 ppm, atom fraction) and older parts of the Milky Way (≈23 ppm). Presumably the differential concentration of deuterium in the inner Solar System is due to the lower volatility of deuterium gas and compounds, enriching deuterium fractions in comets and planets exposed to significant heat from the Sun over billions of years of Solar System evolution.

Deuterium is not radioactive, and is not a significant toxicity hazard. Water enriched in {{sup|2}}H is called heavy water. Deuterium and its compounds are used as a non-radioactive label in chemical experiments and in solvents for {{sup|1}}H-nuclear magnetic resonance spectroscopy. Heavy water is used as a neutron moderator and coolant for nuclear reactors. Deuterium is also a potential fuel for commercial nuclear fusion.

{{Main|Tritium}}

File:H-3 atom.png

Tritium, {{sup|3}}H (atomic mass {{val|3.016049281320|(81)|ul=Da}}), has one proton and two neutrons in its nucleus (triton). It is radioactive, beta decay into helium-3 with half-life {{val|12.33|(2)|u=years}}.{{refn|group=nb|name=NUBASE2020 tropical year}} Traces of {{sup|3}}H occur naturally due to cosmic rays interacting with atmospheric gases. {{sup|3}}H has also been released in nuclear tests. It is used in fusion bombs, as a tracer in isotope geochemistry, and in self-powered lighting devices.

The most common way to produce {{sup|3}}H is to bombard a natural isotope of lithium, {{sup|6}}Li, with neutrons in a nuclear reactor.

Tritium can be used in chemical and biological labeling experiments as a radioactive tracer.{{cite web |author1=Pfizer Japan |website=Pharmaceuticals and Medical Devices Agency (Japan) |at=2.6.5.5B, pp. 6–8 |quote=[{{sup|3}}H]-Labelled LNP-mRNA |title=SARS-CoV-2 mRNA Vaccine (BNT162, PF-07302048) |access-date=5 June 2021 |url=http://www.pmda.go.jp/drugs/2021/P20210212001/672212000_30300AMX00231_I100_1.pdf#page=16 |archive-date=24 March 2022|archive-url=https://web.archive.org/web/20220324171847/http://www.pmda.go.jp/drugs/2021/P20210212001/672212000_30300AMX00231_I100_1.pdf#page=16 }}{{cite journal |doi=10.1093/jn/nxaa092|pmc=7330459 |journal=The Journal of Nutrition |title=Vitamin A Absorption Determined in Rats Using a Plasma Isotope Ratio Method |year=2020 |last1=Green |first1=Joanne Balmer |last2=Green |first2=Michael H. |volume=150 |issue=7 |pages=1977–1981 |pmid=32271921}} Deuterium–tritium fusion uses {{sup|2}}H and {{sup|3}}H as its main reactants, giving energy through the loss of mass when the two nuclei collide and fuse at high temperatures.

{{sup|4}}H (atomic mass {{val|4.02643|(11)}}), with one proton and three neutrons, is a highly unstable isotope. It has been synthesized in the laboratory by bombarding tritium with fast-moving deuterons;

{{cite journal

|author=G. M. Ter-Akopian|year=2002

|title=Hydrogen-4 and Hydrogen-5 from t+t and t+d transfer reactions studied with a 57.5-MeV triton beam

|journal=AIP Conference Proceedings

|volume=610 |pages=920–924

|doi=10.1063/1.1470062

|bibcode=2002AIPC..610..920T

|display-authors=etal}} the triton captured a neutron from the deuteron. The presence of {{sup|4}}H was deduced by detecting the emitted protons. It decays by neutron emission into {{sup|3}}H with a half-life of {{val|139|(10)|ul=ys}} (or {{val|1.39e-22|(10)|u=s}}).

In the 1955 satirical novel The Mouse That Roared, the name quadium was given to the {{sup|4}}H that powered the Q-bomb that the Duchy of Grand Fenwick captured from the United States.

{{sup|5}}H (atomic mass {{val|5.03531|(10)}}), with one proton and four neutrons, is highly unstable. It has been synthesized in the lab by bombarding tritium with fast-moving tritons;

{{cite journal

| author = A. A. Korsheninnikov| year = 2001

| title = Superheavy Hydrogen {{sup|5}}H

| journal = Physical Review Letters

| volume = 87 | issue = 9| pages = 92501

| bibcode=2001PhRvL..87i2501K

| doi = 10.1103/PhysRevLett.87.092501

| pmid=11531562

|display-authors=etal}} one triton captures two neutrons from the other, becoming a nucleus with one proton and four neutrons. The remaining proton may be detected, and the existence of {{sup|5}}H deduced. It decays by double neutron emission into {{sup|3}}H and has a half-life of {{val|86|(6)|ul=ys}} ({{val|8.6e-23|(6)|u=s}}) – the shortest half-life of any known nuclide.

{{sup|6}}H (atomic mass {{val|6.04496|(27)}}) has one proton and five neutrons. It has a half-life of {{val|294|(67)|ul=ys}} ({{val|2.94e-22|(67)|u=s}}). In 2025, ⁶H was produced using an 855MeV electron beam impinging upon on a ⁷Li target.{{cite journal | url=https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.134.162501 | doi=10.1103/PhysRevLett.134.162501 | title=Measurement of ${}^6\mathrm{H}$ Ground State Energy in an Electron Scattering Experiment at MAMI-A1 | date=2025 | last1=Shao | first1=Tianhao | last2=Chen | first2=Jinhui | last3=Pochodzalla | first3=Josef | last4=Achenbach | first4=Patrick | last5=Christmann | first5=Mirco | last6=Distler | first6=Michael O. | last7=Doria | first7=Luca | last8=Esser | first8=Anselm | last9=Geratz | first9=Julian | last10=Helmel | first10=Christian | last11=Hoek | first11=Matthias | last12=Kino | first12=Ryoko | last13=Klag | first13=Pascal | last14=Ma | first14=Yu-Gang | last15=Markus | first15=David | last16=Merkel | first16=Harald | last17=Mihovilovič | first17=Miha | last18=Müller | first18=Ulrich | last19=Nagao | first19=Sho | last20=Nakamura | first20=Satoshi N. | last21=Nishi | first21=Kotaro | last22=Nishida | first22=Ken | last23=Oura | first23=Fumiya | last24=Pätschke | first24=Jonas | last25=Schlimme | first25=Björn Sören | last26=Sfienti | first26=Concettina | last27=Steger | first27=Daniel | last28=Steinen | first28=Marcell | last29=Thiel | first29=Michaela | last30=Wilczek | first30=Andrzej | journal=Physical Review Letters | volume=134 | issue=16 | page=162501 | pmid=40344098 | arxiv=2501.01232 | display-authors=1 }}

{{sup|7}}H (atomic mass {{val|7.05275|(108)}}) has one proton and six neutrons. It was first synthesized in 2003 by a group of Russian, Japanese and French scientists at Riken's Radioactive Isotope Beam Factory by bombarding hydrogen with helium-8 atoms; all six of the helium-8's neutrons were donated to the hydrogen nucleus. The two remaining protons were detected by the "Riken telescope", a device made of several layers of sensors, positioned behind the target of the RI Beam cyclotron. {{sup|7}}H has a half-life of {{val|652|(558)|ul=ys}} ({{val|6.52e-22|(558)|u=s}}).

{{sup|4}}H and {{sup|5}}H decay directly to {{sup|3}}H, which then decays to stable Helium-3. Decay of the heaviest isotopes, {{sup|6}}H and {{sup|7}}H, has not been experimentally observed.{{NUBASE2020|ref}}

:$\backslash begin\{array\}\{rcl\}\backslash \backslash$

\ce{^3_1H} &\ce{->[12.32\ \ce{y}]} &\ce{{^3_2He} + e^-} \\

\ce{^4_1H} &\ce{->[139\ \ce{ys}]} &\ce{{^3_1H} + {^1_0n}} \\

\ce{^5_1H} &\ce{->[86\ \ce{ys}]} &\ce{{^3_1H} + {2^1_0n}} \\{}

\end{array}

Decay times are in yoctoseconds ({{val|e=-24|u=s}}) for all these isotopes except {{sup|3}}H, which is in years.

• Hydrogen atom
• Hydrogen isotope biogeochemistry
• Hydrogen-4.1 (Muonic helium)
• Muonium – acts like an exotic light isotope of hydrogen
• {{Commons-inline|Isotopes of hydrogen}}

{{reflist|group=nb}}

{{Reflist}}

• {{cite web

|first=B. |last=Dumé

|date=7 March 2003

|title=Hydrogen-7 makes its debut

|url=http://physicsworld.com/cws/article/news/2003/mar/07/hydrogen-7-makes-its-debut

|work=Physics World

|url-access=registration

}}

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Category:Hydrogen

Hydrogen