Hydrogen-5

Properties and data of the isotope ⁵H.

Contents

Hydrogen-5 is an extremely unstable, neutron-rich radioisotope of the chemical element hydrogen. In addition to the proton, which is element-specific for hydrogen, the atomic nucleus of the isotope consists of 4 neutrons, which results in the mass number 5. The highly radioactive nuclide, which can only be produced artificially, has no practical significance; ⁵H is for academic purposes only.

The nuclide was synthesized by bombarding tritium (see hydrogen-3) with fast-moving tritium nuclei [1,2].

See also: List of individual Hydrogen isotopes (and general data sources).

General data

Name of the isotope:Hydrogen-5; H-5Symbol:⁵H or 51HMass number A:5 (= number of nucleons)Atomic number Z:1 (= number of protons)Neutrons N:4Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):4 (= neutron-proton ratio)Neutron excess (N-Z):3Isotopic mass:5.03531(10) u (atomic weight of Hydrogen-5)Nuclide mass:5.0347614 u (calculated nuclear mass without electrons)Mass excess:32.89105 MeVMass defect:0.0071746960000008 u (per nucleus)Nuclear binding energy:6.68318628 MeV (per nucleus)
1.33663726 MeV (average binding energy per nucleon)Half-life:861 zsDecay constant λ:8.050489901973 × 10⁺²¹ s^-1Specific activity α:9.696236836236 × 10⁺⁴⁴ Bq g^-1
2.620604550334 × 10⁺³⁴ Ci g^-1Spin and parity:
(nuclear angular momentum)(1/2+)Mirror nucleus:Beryllium-5Year of discovery:1987

Radioactive Decay

Half-life T_½ = 861 zs respectively 8.61 × 10^-23 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
2n	³H	100 %	22.396(89) MeV

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 4) and isobaric (same nucleon number A = 5) with Hydrogen-5. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 4	Isobar A = 5
1	⁵H	⁵H
2	⁶He	⁵He
3	⁷Li	⁵Li
4	⁸Be	⁵Be
5	⁹B
6	¹⁰C
7	¹¹N
8	¹²O
9	¹³F

External data and identifiers

Adopted Levels, Gammas:NuDat 5H

Literature and References

[1] - A. A. Korsheninnikov, M. S. Golovkov, I. Tanihata et al.:
Superheavy Hydrogen ⁵H.
In: Physical Review Letters, (2001), DOI 10.1103/PhysRevLett.87.092501.

[2] - G. M. Ter-Akopian, Yu. Ts. Oganessian, D. D. Bogdanov et al.:
Hydrogen-4 and Hydrogen-5 from t+t and t+d transfer reactions studied with a 57.5-MeV triton beam.
In: AIP Conference Proceedings, 610, 920-924, (2002), DOI 10.1063/1.1470062.