Cobalt-57

Properties and data of the isotope ⁵⁷Co.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Cobalt-57 is a radioisotope of the chemical element cobalt with the mass number 57. The atomic nucleus of the nuclide consists of 30 neutrons and 27 protons.

The radioactive isotope was first observed and characterized – according to a report from 1941 [1] – during the irradiation of iron-57 with deuterons (hydrogen-2 nuclei):

⁵⁷Fe(d,2n)⁵⁷Co.

Cobalt-57 is used to produce standards for the calibration of radiometric devices and medical gamma cameras. Vitamin B12 labelled with Co-57 is used in diagnostic kits, e.g. to examine iron deficiency anemia; see also Schilling test.

See also: List of individual Cobalt isotopes (and general data sources).

General data

Name of the isotope:Cobalt-57; Co-57Symbol:⁵⁷Co or 5727CoMass number A:57 (= number of nucleons)Atomic number Z:27 (= number of protons)Neutrons N:30Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.1111111111111 (= neutron-proton ratio)Neutron excess (N-Z):3Isotopic mass:56.9362898(6) u (atomic weight of Cobalt-57)Nuclide mass:56.9214785 u (calculated nuclear mass without electrons)Mass excess:-59.34567 MeVMass defect:0.534933544 u (per nucleus)Nuclear binding energy:498.28738663 MeV (per nucleus)
8.74188398 MeV (average binding energy per nucleon)Separation energy:S_N = 11.3765(6) MeV (first neutron)
S_P = 6.0275(4) MeV (first proton)Half-life:271.74(6) dDecay constant λ:2.952284099520 × 10^-8 s^-1Specific activity α:3.174834054618 × 10⁺¹⁴ Bq g^-1
8580.6325800495 Ci g^-1Spin and parity:
(nuclear angular momentum)7/2-Isobaric spin: 3/2Magnetic dipole moment:μ(μ_N) = +4.720(10)Quadrupole moment Q:+0.52(9) barn (100 fm²)Nuclear g-factor:g_l = 1.3485714285714Mirror nucleus:Zinc-57Year of discovery:1941

Radioactive Decay

Half-life T_½ = 271.74(6) d respectively 2.3478336 × 10⁷ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC	⁵⁷Fe	100 %	0.8364(6) MeV	0.12206065(12) MeV 85.60(17) %

Parent Nuclides

Direct parent isotope is: ⁵⁷Ni.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 30) and isobaric (same nucleon number A = 57) with Cobalt-57. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 30	Isobar A = 57
13	⁴³Al
14	⁴⁴Si
15	⁴⁵P
16	⁴⁶S
17	⁴⁷Cl
18	⁴⁸Ar
19	⁴⁹K	⁵⁷K
20	⁵⁰Ca	⁵⁷Ca
21	⁵¹Sc	⁵⁷Sc
22	⁵²Ti	⁵⁷Ti
23	⁵³V	⁵⁷V
24	⁵⁴Cr	⁵⁷Cr
25	⁵⁵Mn	⁵⁷Mn
26	⁵⁶Fe	⁵⁷Fe
27	⁵⁷Co	⁵⁷Co
28	⁵⁸Ni	⁵⁷Ni
29	⁵⁹Cu	⁵⁷Cu
30	⁶⁰Zn	⁵⁷Zn
31	⁶¹Ga
32	⁶²Ge
33	⁶³As
34	⁶⁴Se

External data and identifiers

CAS:13981-50-5InChI Key:GUTLYIVDDKVIGB-YPZZEJLDSA-NSMILES:[57Co]PubChem:ID 104851Adopted Levels, Gammas:NuDat 57Co

Literature and References

[1] - J. J. Livingood, G. T. Seaborg:
Radioactive Isotopes of Cobalt.
In: Physical Review, 60, 913, (1941), DOI 10.1103/PhysRev.60.913.

[2] - Jun Young Lee et al.:
Production of cobalt-57 for industrial and medical applications in RFT-30 cyclotron facility.
In: Journal of Radioanalytical and Nuclear Chemistry, 332, 5097–5103, (2023), DOI 10.1007/s10967-023-08978-2.