Scandium-55

Properties and data of the isotope ⁵⁵Sc.

Content

General data

Name of the isotope:Scandium-55; Sc-55Symbol:⁵⁵Sc or 5521ScMass number A:55 (= number of nucleons)Atomic number Z:21 (= number of protons)Neutrons N:34Isotopic mass:54.96762(49) u (atomic weight of Scandium-55)Nuclide mass:54.9561 u (calculated nuclear mass without electrons)Mass excess:-30.16178 MeVMass defect:0.491312816 u (per nucleus)Nuclear binding energy:457.65494023 MeV (per nucleus)
8.32099891 MeV (average binding energy per nucleon)Separation energy:S_N = 4.34(53) MeV (first neutron)
S_P = 12.29(46) MeV (first proton)Half-life:105(6) msDecay constant λ:6.6014017196185 s^-1Specific activity α:7.361957597883 × 10⁺²² Bq g^-1
1989718269698.3 Ci g^-1Spin and parity:
(nuclear angular momentum)(7/2-)Year of discovery:1990

Radioactive Decay

Half-life T_½ = 105(6) ms respectively 1.05 × 10^-1 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	⁵⁵Ti	> 99.9 %	11.51(48) MeV
β^-, n	⁵⁴Ti	< 0.1 %	7.39(46) MeV

Parent Nuclides

Direct parent isotope is: ⁵⁵Ca.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 34) and isobaric (same nucleon number A = 55) with Scandium-55. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 34	Isobar A = 55
17	⁵¹Cl
18	⁵²Ar
19	⁵³K	⁵⁵K
20	⁵⁴Ca	⁵⁵Ca
21	⁵⁵Sc	⁵⁵Sc
22	⁵⁶Ti	⁵⁵Ti
23	⁵⁷V	⁵⁵V
24	⁵⁸Cr	⁵⁵Cr
25	⁵⁹Mn	⁵⁵Mn
26	⁶⁰Fe	⁵⁵Fe
27	⁶¹Co	⁵⁵Co
28	⁶²Ni	⁵⁵Ni
29	⁶³Cu	⁵⁵Cu
30	⁶⁴Zn	⁵⁵Zn
31	⁶⁵Ga
32	⁶⁶Ge
33	⁶⁷As
34	⁶⁸Se
35	⁶⁹Br
36	⁷⁰Kr
37	⁷¹Rb