All of the atomic nuclei of the chemical element dubnium are summarized under dubnium isotopes; these consist of an atomic nucleus with 105 protons and in the uncharged state of 105 electrons. The difference between the individual dubnium isotopes lies in the number of neutrons in the nucleus - and thus in the mass number

Dubnium is an exclusively synthetically produced radioactive chemical element that is not known in nature.

The first man-made and proven nuclide was Dubnium-261 (1968). Since then, a total of 13 radioisotopes have been characterized, of which Db-268 has the longest half-life at 32 hours.

## Isotope Table: Dubnium

### Atomic Properties

Isotope Nuclide | Z | A | N | Name | Atomic Mass [Nuclear Mass] {Mass Excess} | Spin I(h/2π) | μ | Parent |
---|---|---|---|---|---|---|---|---|

1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |

^{255}Db | 105 | 255 | 150 | Dubnium-255 | 255.10692(38) u [255.0493282 u] {99.59534 MeV} | |||

^{256}Db | 105 | 256 | 151 | Dubnium-256 | 256.10789(26) u [256.0502982 u] {100.49889 MeV} | |||

^{257}Db | 105 | 257 | 152 | Dubnium-257 | 257.10758(22) u [257.0499882 u] {100.21012 MeV} | (9/2+) | ^{261}Bh | |

^{257m}Db | 105 | 257 | 152 | Dubnium-257m | 257.10758(22) u [257.0499882 u] {100.21012 MeV} | (1/2-) | ||

^{258}Db | 105 | 258 | 153 | Dubnium-258 | 258.10928(33) u [258.0516882 u] {101.79366 MeV} | (5+,6+) | ^{262}Bh | |

^{258m}Db | 105 | 258 | 153 | Dubnium-258m | 258.10928(33) u [258.0516882 u] {101.79366 MeV} | (1-) | ||

^{259}Db | 105 | 259 | 154 | Dubnium-259 | 259.10949(6) u [259.0518982 u] {101.98928 MeV} | (9/2+) | ||

^{260}Db | 105 | 260 | 155 | Dubnium-260 | 260.11130(10) u [260.0537082 u] {103.67528 MeV} | ^{264}Bh | ||

^{261}Db | 105 | 261 | 156 | Dubnium-261 | 261.11198(12) u [261.0543882 u] {104.3087 MeV} | |||

^{262}Db | 105 | 262 | 157 | Dubnium-262 | 262.11407(15) u [262.0564782 u] {106.25552 MeV} | ^{266}Bh | ||

^{263}Db | 105 | 263 | 158 | Dubnium-263 | 263.11499(18) u [263.0573982 u] {107.1125 MeV} | |||

^{264}Db | 105 | 264 | 159 | Dubnium-264 | ||||

^{265}Db | 105 | 265 | 160 | Dubnium-265 | ||||

^{266}Db | 105 | 266 | 161 | Dubnium-266 | 266.12103(30) u [266.0634382 u] {112.73872 MeV} | |||

^{267}Db | 105 | 267 | 162 | Dubnium-267 | 267.12246(44) u [267.0648682 u] {114.07076 MeV} | |||

^{268}Db | 105 | 268 | 163 | Dubnium-268 | 268.12567(57) u [268.0680782 u] {117.06085 MeV} | ^{272}Bh | ||

^{269}Db | 105 | 269 | 164 | Dubnium-269 | ||||

^{270}Db | 105 | 270 | 165 | Dubnium-270 | 270.13130(66) u [270.0737082 u] {122.30516 MeV} |

### Radioactive Decay Properties

Isotope | Radioactive Decay | AE | Extern | |||
---|---|---|---|---|---|---|

Half-life | Decay Mode | Probability | Energy | |||

1 | 10 | 11 | 12 | 13 | 14 | 15 |

Db-255 | ca. 1.6 s | α → ^{251}LrSF ^{}div | ca. 80 % ca. 20 % | 9.44(20) MeV | AL | |

Db-256 | ca. 1.6 s | SF ^{}divEC → ^{256}Rfα → ^{252}Lr | ? 30(11) % 70(11) % | 6.28(24) MeV 9.34(3) MeV | AL | |

Db-257 | 2.3(2) s | α → ^{253}LrSF ^{}div | ≥ 94 % ≤ 6 % | 9.207(20) MeV | AL | |

Db-257m | 0.67(6) s | α → ^{253}LrSF ^{}div | ≥ 87 % ≤ 6 % | 370 keV | AL | |

Db-258 | 4.3(5) s | α → ^{254}LrEC/β ^{+} → ^{258}Rf | 77(8) % 23(8) % | 9.50(5) MeV 5.46(31) MeV | AL | |

Db-258m | 1.9(5) s | EC/β^{+} → ^{258}Rfα → ^{254}Lr | 36(10) % 64(10) % | +x keV | AL | |

Db-259 | 0.51(16) s | α → ^{255}Lr | ? | 9.62(5) % | AL | |

Db-260 | 1.52(13) s | α → ^{256}LrSF ^{}divEC → ^{259}Rf | ≥ 90.4(6) % ≤ 9.6(6) % < 2.5 % | 9.50(4) MeV 4.53(22) MeV | AL | |

Db-261 | 1.8(4) s | α → ^{257}LrSF ^{}div | ≥ 82 % ≤ 18 % | 9.22(10) MeV | AL | |

Db-262 | 35(5) s | α → ^{258}LrSF ^{}div | ca. 67 % ca. 33 % | 9.05(10) MeV | AL | |

Db-263 | ca. 27 s | α → ^{259}LrSF ^{}div | 43(14) % 57(14) % | 8.83(15) MeV | AL | |

Db-264 | - unbekannt - | |||||

Db-265 | - unbekannt - | |||||

Db-266 | 0.4 h | SF ^{}divα → ^{262}LrEC → ^{266}Rf | ca. 100 % ? ? | 8.21(20) MeV | AL | |

Db-267 | ca. 73 min | SF ^{}div | ~ 100 % | AL | ||

Db-268 | 28(3) h | SF ^{}divEC/β ^{+} → ^{268}Rfα → ^{264}Lr | ~ 100 % ? ? | 8.26(30) MeV | AL | |

Db-269 | - unbekannt - | |||||

Db-270 | 15(+10-4) h | α ^{266}LrSF ^{}div | ? ~ 100 % | 8.26(20) MeV | AL |

Notes (related to the columns):

1 - nuclide, isotope symbol.

2 - *Z* = number of protons (atomic number).

3 - Mass number *A*.

4 - *N* = number of neutrons.

5 - Identification of the Dubnium isotope.

6 - Relative atomic mass of the Dubnium isotope (isotopic mass including electrons) and the mass of the atomic nucleus in square brackets (nuclear mass, nuclide mass without electrons), each related to ^{12}C = 12.00000 [2]. In addition, the mass excess is given in MeV.

7 - Nuclear spin *I*, unit: h/2π.

8 - Nuclear magnetic moment μ_{mag}.

9 - Source nuclides: Possible, assumed or actual source nuclides (mother nuclides, parent nuclides). If applicable, the corresponding decay modes can be found in the data for the respective starting nuclide.

10 - Decay: Half-live of the Dubnium isotope (a = years; ; d = days; h = hours; min = minutes; s = seconds).

11 - Decay: type of decay into the respective daughter nuclides with n = neutron emission; p = proton emission; α = alpha decay; β^{-} = beta minus decay with electron emission; EC = electron capture; β^{+} = positron emission; ε = β^{+} and/or EC; Iso = isomeric transition; CD = cluster decay; SF = spontaneous decay.

12 - Decay percentage in percent (%).

13 - Decay energy; Particle energy related to decay type.

14 - AE = Excitation energy for metastable nuclei.

15 - Other information and notes: AL = Adopted Levels (link to external data [1]).

Miscellaneous:

()- Numbers in brackets: uncertainty to represent the spread of the reported value.

~ - Theoretical values or systematic trends.

- unlisted-: Nuclides that have already been mentioned in the literature but for some reason can no longer be found in the current nuclide tables because their discovery e.g. has not confirmed.

## Literature Sources and References

**Properties of the Dubnium nucleides**

[1] - NuDat: National Nuclear Data Center, Brookhaven National Laboratory, based on ENSDF and the Nuclear Wallet Cards.

[2] - G. Audi et. al.: The NUBASE evaluation of nuclear and decay properties. Nuclear Physics, (2003), DOI 10.1016/j.nuclphysa.2003.11.001.

[3] - Live Chart of Nuclides. Nuclear structure and decay data.

**Dubnium: NMR properties **

[4] - N. J. Stone: Table of nuclear magnetic dipole and electric quadrupole moments. Atomic Data and Nuclear Data Tables, (2005), DOI 10.1016/j.adt.2005.04.001.

[5] - Pekka Pyykkö: Year-2008 nuclear quadrupole moments. Molecular Physics, (2008), DOI 10.1080/00268970802018367.

[6] - Pekka Pyykkö: Year-2017 nuclear quadrupole moments. Molecular Physics, (2018), DOI 10.1080/00268976.2018.1426131.

[7] - N. J. Stone: Table of recommended nuclear magnetic dipole moments. IAEA, (2019).

**More sources:**

[8] - **Isotopic abundances, atomic weights and isotopic masses:** see respective keyword.

**Category: Isotopes**

**Last update: **05.07.2020

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