Chromium-55

Properties and data of the isotope ⁵⁵Cr.

Contents

General data

Name of the isotope:Chromium-55; Cr-55Symbol:⁵⁵Cr or 5524CrMass number A:55 (= number of nucleons)Atomic number Z:24 (= number of protons)Neutrons N:31Isotopic mass:54.9408373(4) u (atomic weight of Chromium-55)Nuclide mass:54.9276717 u (calculated nuclear mass without electrons)Mass excess:-55.1097 MeVMass defect:0.515575864 u (per nucleus)Nuclear binding energy:480.25582386 MeV (per nucleus)
8.73192407 MeV (average binding energy per nucleon)Separation energy:S_N = 6.24626(19) MeV (first neutron)
S_P = 12.506(15) MeV (first proton)Half-life:3.497(3) minDecay constant λ:0.0033035324590599 s^-1Specific activity α:3.684136630339 × 10⁺¹⁹ Bq g^-1
995712602.79438 Ci g^-1Spin and parity:
(nuclear angular momentum)3/2-Year of discovery:1952

Radioactive Decay

Half-life T_½ = 3.497(3) min (minutes) respectively 2.0982 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	⁵⁵Mn	100 %	2.6027(4) MeV

Parent Nuclides

Direct parent isotope is: ⁵⁵V.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 31) and isobaric (same nucleon number A = 55) with Chromium-55. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 31	Isobar A = 55
15	⁴⁶P
16	⁴⁷S
17	⁴⁸Cl
18	⁴⁹Ar
19	⁵⁰K	⁵⁵K
20	⁵¹Ca	⁵⁵Ca
21	⁵²Sc	⁵⁵Sc
22	⁵³Ti	⁵⁵Ti
23	⁵⁴V	⁵⁵V
24	⁵⁵Cr	⁵⁵Cr
25	⁵⁶Mn	⁵⁵Mn
26	⁵⁷Fe	⁵⁵Fe
27	⁵⁸Co	⁵⁵Co
28	⁵⁹Ni	⁵⁵Ni
29	⁶⁰Cu	⁵⁵Cu
30	⁶¹Zn	⁵⁵Zn
31	⁶²Ga
32	⁶³Ge
33	⁶⁴As
34	⁶⁵Se
35	⁶⁶Br
36	⁶⁷Kr