Periodic Table/Fermium/²⁵⁵Fm

← 254Fm256Fm →

²⁵⁵Fm

Fermium-255

Radioactive· Half-life: 20.1 h

Nuclear Propertiesbinding energy · spin-parity · abundance

Protons (Z)

100

Neutrons (N)

155

Mass Number (A)

255

Atomic Mass

255.089963AMU

Spin / Parity

7/2+

Binding E/A

7.236keV

Natural Abundance

Trace / None

Half-life

20.1 h

Decay Modesoverview · half-life · α · β⁻ · β⁺

α

100.0%

SF

2.4%

Decay Chain

²⁵⁵FmFermium20.1 h

α100.0%

²⁵¹CfCalifornium898 y

α100.0%

²⁴⁷CmCurium15.6 My

α100.0%

²⁴³PuPlutonium4.96 h

β⁻100.0%

²⁴³AmAmericium7.35 ky

α100.0%

²³⁹NpNeptunium2.36 d

β⁻100.0%

α²³⁵Pa

²³⁹PuPlutonium24.1 ky

α100.0%

²³⁵UUranium704 My

α100.0%

20Ne²¹⁵Pb8.00%

25Ne²¹⁰Pb8.00%

28Mg²⁰⁷Hg8.00%

²³¹ThThorium1.06 d

β⁻100.0%

²³¹PaProtactinium32.6 ky

α100.0%

24Ne²⁰⁷Tl13.4%

23F²⁰⁸Pb9.90%

²²⁷AcActinium21.8 y

β⁻98.6%

α²²³Fr1.38%

²²⁷ThThorium18.7 d

α100.0%

²²³RaRadium11.4 d

α100.0%

¹⁴C²⁰⁹Pb8.90%

²¹⁹RnRadon3.96 s

α100.0%

²¹⁵PoPolonium1.78 ms

α100.0%

β⁻²¹⁵At2.30%

²¹¹PbLead36.2 min

β⁻100.0%

²¹¹BiBismuth2.14 min

α100.0%

β⁻²¹¹Po0.28%

²⁰⁷TlThallium4.77 min

β⁻100.0%

²⁰⁷PbLeadSTABLE

19-step decay chain → stable · Primary path shown · branching ratios indicated

Other Isotopes of Fermium

241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260

← Back to FermiumData: IAEA NDS · ENSDF