Cerium-140

Properties and data of the isotope ¹⁴⁰Ce.

Contents

Cerium-140 is a stable isotope of the chemical element cerium, which has 82 neutrons in its atomic nucleus in addition to the element-specific 58 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 140.

Cerium-140 was first identified as a stable isotope in 1925. A natural sample of cerium tribromide was analyzed by mass spectrometry, revealing a distinct mass line at 140 and a fainter one at 142. The prominent line at mass number 140 showed that cerium-140 is the major isotope of the element; it was the first unambiguously identified cerium isotope [1].

Natural cerium contains approximately 88.45 % by mass of ¹⁴⁰Ce. There are no practical applications for isotopically pure cerium-140.

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

General data

Name of the isotope:Cerium-140; Ce-140Symbol:¹⁴⁰Ce or 14058CeMass number A:140 (= number of nucleons)Atomic number Z:58 (= number of protons)Neutrons N:82Isotopic mass:139.90544(2) u (atomic weight of Cerium-140)Nuclide mass:139.8736246 u (calculated nuclear mass without electrons)Mass excess:-88.08207 MeVMass defect:1.258934968 u (per nucleus)Nuclear binding energy:1172.69036908 MeV (per nucleus)
8.37635978 MeV (average binding energy per nucleon)Separation energy:S_N = 9.1878(24) MeV (first neutron)
S_P = 8.1408(13) MeV (first proton)Half-life:stableSpin and parity:
(nuclear angular momentum)0+Charge radius:4.8771(18) femtometer fmYear of discovery:1925

Parent Nuclides

Direct parent isotopes are: ¹⁴⁰Pr, ¹⁴⁰La, ¹⁴⁴Nd.

Occurrence

Comparison of the natural Cerium isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):

	Atomic Mass m_a	Quantity	Half-life	Spin
Cerium Isotopic mixture	140.116 u	100 %
Isotope ¹⁴²Ce	141.90925(2) u	11.114(51) %	stable	0+
Isotope ¹⁴⁰Ce	139.90544(2) u	88.449(51) %	stable	0+
Isotope ¹³⁸Ce	137.90599(7) u	0.251(2) %	stable	0+
Isotope ¹³⁶Ce	135.907129(3) u	0.186(2) %	stable	0+

Nuclear Isomers

Nuclear isomers or excited states with the activation energy in keV related to the ground state.

Nuclear Isomer	Excitation Energy	Half-life	Spin
^140mCe	2107.854(24) keV	7.3(15) μs	6+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 82) and isobaric (same nucleon number A = 140) with Cerium-140. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 82	Isobar A = 140
45	¹²⁷Rh
46	¹²⁸Pd
47	¹²⁹Ag
48	¹³⁰Cd
49	¹³¹In
50	¹³²Sn	¹⁴⁰Sn
51	¹³³Sb	¹⁴⁰Sb
52	¹³⁴Te	¹⁴⁰Te
53	¹³⁵I	¹⁴⁰I
54	¹³⁶Xe	¹⁴⁰Xe
55	¹³⁷Cs	¹⁴⁰Cs
56	¹³⁸Ba	¹⁴⁰Ba
57	¹³⁹La	¹⁴⁰La
58	¹⁴⁰Ce	¹⁴⁰Ce
59	¹⁴¹Pr	¹⁴⁰Pr
60	¹⁴²Nd	¹⁴⁰Nd
61	¹⁴³Pm	¹⁴⁰Pm
62	¹⁴⁴Sm	¹⁴⁰Sm
63	¹⁴⁵Eu	¹⁴⁰Eu
64	¹⁴⁶Gd	¹⁴⁰Gd
65	¹⁴⁷Tb	¹⁴⁰Tb
66	¹⁴⁸Dy	¹⁴⁰Dy
67	¹⁴⁹Ho	¹⁴⁰Ho
68	¹⁵⁰Er
69	¹⁵¹Tm
70	¹⁵²Yb
71	¹⁵³Lu
72	¹⁵⁴Hf
73	¹⁵⁵Ta
74	¹⁵⁶W

Data changes (history)

Isotopic mass: The atomic mass value of the cerium-140 isotope given here (above) corresponds to the recommendation of CIAAW and IUPAC. The more precise value of 139.9054484(14) u can be found in nuclear databases.

External data and identifiers

Adopted Levels, Gammas:NuDat 140Ce

Literature and References

[1] - F.W. Aston:
The mass-spectra of chemical elements. - Part VI. Accelerated anode rays continued.
In: The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, 49, 294, (1925), DOI 10.1080/14786442508634698.