Isotopes of hydrogen

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Hydrogen (H)
Standard atomic mass: 1.00794(7) u

The isotopes of hydrogen include two stable and five unstable isotopes.

Contents

1 Isotopes

1.1 Hydrogen-1 (protium)
1.2 Hydrogen-2 (deuterium)
1.3 Hydrogen-3 (tritium)
1.4 Hydrogen-4
1.5 Hydrogen-5
1.6 Hydrogen-6
1.7 Hydrogen-7

2 Table

2.1 Notes

3 References
4 In fiction
5 External links

Isotopes

Hydrogen-1 (protium)

For more details on this topic, see Hydrogen atom.

Hydrogen-2 (deuterium)

For more details on this topic, see Deuterium.

Hydrogen-3 (tritium)

For more details on this topic, see Tritium.

Hydrogen-4

For more details on this topic, see Hydrogen-4.

Hydrogen-4 is highly unstable. The nucleus consists of a proton and three neutrons. It has been synthesised in the laboratory by bombarding tritium with fast-moving deuterium nuclei. In this experiment, the tritium nuclei captured neutrons from the fast-moving deuterium nucleus. The presence of the hydrogen-4 was deduced by detecting the emitted protons. It decays through neutron emission and has a half-life of 1.4×10⁻²² seconds.

Hydrogen-5

For more details on this topic, see Hydrogen-5.

Hydrogen-5 is highly unstable. The nucleus consists of a proton and four neutrons. It has been synthesised in the laboratory by bombarding tritium with fast-moving tritium nuclei. In this experiment, the one tritium nucleus 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 hydrogen-5 deduced. It decays through double neutron emission and has a half-life of perhaps 10⁻²¹ seconds (sources vary).

Hydrogen-6

Hydrogen-6 decays through triple neutron emission and has a half-life of 3×10⁻²² seconds.

Hydrogen-7

Hydrogen-7 consists of a proton and six neutrons. It was first synthesised in 2003 by a group of Russian, Japanese and French scientists at RIKEN's RI Beam Science Laboratory by bombarding hydrogen with helium-8 atoms. In the resulting reaction, the helium-8's neutrons were donated to the hydrogen's nucleus. The two remaining protons were detected by the "RIKEN telescope", a device composed of several layers of sensors, positioned behind the target of the RI Beam cyclotron.

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
H-1	1	0	1.00782503207(10)	STABLE [>2.8×10²³ a]	1/2+	0.999885(70)	0.999816-0.999974
H-2	1	1	2.0141017778(4)	STABLE	1+	0.000115(70)	0.000026-0.000184
H-3	1	2	3.0160492777(25)	12.32(2) a	1/2+
H-4	1	3	4.02781(11)	1.39(10)×10^-22 s [4.6(9) MeV]	2-
H-5	1	4	5.03531(11)	>9.1×10^-22 s ?	(1/2+)
H-6	1	5	6.04494(28)	2.90(70)×10^-22 s [1.6(4) MeV]	2-#
H-7	1	6	7.05275(108)#	2.3(6)×10^-23# s [20(5)# MeV]	1/2+#

Notes

The isotopic composition refers to that in water.
The precision of the isotope abundances and atomic mass is limited through variations. The given ranges should be applicable to any normal terrestrial material.
Commercially available materials may have been subjected to an undisclosed or inadvertent isotopic fractionation. Substantial deviations from the given mass and composition can occur.
Tank hydrogen has a ²H abundance as low as 3.2×10^-5 (mole fraction).
Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.

References

Isotope masses from [Ame2003 Atomic Mass Evaluation] by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in Nuclear Physics A729 (2003).
Isotopic compositions and standard atomic masses from [Atomic weights of the elements. Review 2000 (IUPAC Technical Report)]. Pure Appl. Chem. Vol. 75, No. 6, pp. 683-800, (2003) and [Atomic Weights Revised (2005)].
Half-life, spin, and isomer data selected from these sources. Editing notes on this article's talk page.
* Audi, Bersillon, Blachot, Wapstra. [The Nubase2003 evaluation of nuclear and decay properties], Nuc. Phys. A 729, pp. 3-128 (2003).
* National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the [NuDat 2.1 database] (retrieved Sept. 2005).
* David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition, online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.

In fiction

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

External links

[News of hydrogen-7 discovery]
[Article on hydrogen-4 and hydrogen-5] (login required)

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