View source for Isotopes of fermium

[[Fermium]] is an artificial element, and has no stable or naturally occuring isotopes. The first isotope to be discovered was {{Nuclide|Z=100|A=255}}, in fallout from the first test of a hydrogen bomb, codenamed 'Ivy Mike', in 1952. {{Nuclide|Z=100|A=250}} was discovered independently in 1954.

{| class="wikitable" style="white-space:nowrap;" width=100%
! rowspan=2 colspan=2 | Symbol
! Z([[proton|p]])
! N([[neutron|n]])
! Mass/u
! rowspan=2 | <u>Excess energy</u><br/>MeV
! rowspan=2 | <u>Binding energy/A</u><br/>MeV
! rowspan=2 | <u>β<sup>−</sup>-decay energy</u><br/>MeV
! rowspan=2 | Spin
! rowspan=2 | Half life
! rowspan=2 | Decay mode,<br/>proportion
|-
! colspan="3" | Excitation energy/MeV
|-
| colspan=2 | <sup>242</sup>Fm
| 100
| 142
| 242.073 43(43)#
| 68 400(401)#
| 7465(2)#
| —
| align=center | 0
| 0.8(2) ms
| SF (? %); α (? %)
|-
| colspan=2 | <sup>243</sup>Fm
| 100
| 143
| 
| 69 260(220)#
| 
| 
| align=center | −{{frac|7|2}}#
| 210(60) ms
| α;<ref group="Note">The α ranching ratio depends on the uncertain branching ratio of the daughter <sup>239</sup>Cf.</ref> β<sup>+</sup> (? %); SF (59%#)
|-
| colspan=2 | <sup>244</sup>Fm
| 100
| 144
| 
| 69 010(280)
| 
| 
| align=center | 0
| 3.3(0.5) ms
| SF (≈100%); α (0.4%#)
|-
| colspan=2 | <sup>245</sup>Fm
| 100
| 145
| 
| 70 220(280)#
| 
| 
| align=center | +{{frac|2}}#
| 4.2(13) s
| α (? %); β<sup>+</sup> (4.2%#); SF (0.13%#)
|-
| colspan=2 | <sup>246</sup>Fm
| 100
| 146
| 
| 70 140(40)
| 
| 
| align=center | 0
| 1.1(2) s
| α (? %); β<sup>+</sup> (> 10%); SF (4.5–13%); β<sup>+</sup>SF (10–5%)
|-
| colspan=2 | <sup>247</sup>Fm
| 100
| 147
| 
| 71 580(140)#
| 
| 
| align=center | +{{frac|5|2}}#
| 35(4) s
| α (≥ 50%); β<sup>+</sup> (≤ 50%)
|-
| rowspan=3 | 
| <sup>247''m''</sup>Fm
| colspan=3 align=center | non-existent
| 
| 
| 
| 
| 9.2(23) s
| α (≈100%); IT (? %)
|-
| <sup>247''p''</sup>Fm
| colspan=3 align=center | 150(100)#
| 71 730(170)#
| 
| 
| align=center | (+{{frac|7|2}})
| 
| 
|-
| <sup>247''q''</sup>Fm
| colspan=3 align=center | 400(150)#
| 71 980(210)#
| 
| 
| 
| 
| 
|-
| colspan=11 | Values marked # are estimated from systematic trends rather than experimentally measured.<br/>Spins quoted in parentheses are uncertain in value and/or parity.<br/>''Sources'': Except as otherwise noted, 
:isotopic masses and associated energies are taken from the AME 2003 dataset;<ref name="AME">{{AME 2003}}</ref>
:nuclear spins and decay properties are taken from N<small>UBASE</small> 2003.<ref name="Nubase">{{Nubase 2003}}.</ref>
|}

==Notes and references==
===Notes===
{{reflist|group=Note}}

===References===
{{reflist}}

[[Category:Isotopes by element|Fermium]]

{{CC-BY-3.0}}