Lead-178

Properties and data of the isotope ¹⁷⁸Pb.

Contents

Lead-178 is a radioisotope of the chemical element lead, which has 96 neutrons in its atomic nucleus in addition to the element-specific 82 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 178. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ¹⁷⁸Pb is exclusively for academic purposes and experimental research.

The proton-rich nuclide was first mentioned in a conference paper in 2003 [1]. Experimental confirmation of the existence of lead-178 was published in 2016 [2]; according to this, Pb-178 could be produced and identified by irradiating a palladium-104 template with krypton-78 ions at an energy of 358 MeV:

¹⁰⁴Pd(⁷⁸Kr,4n)¹⁷⁸Pb.

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

General data

Name of the isotope:Lead-178; Pb-178Symbol:¹⁷⁸Pb or 17882PbMass number A:178 (= number of nucleons)Atomic number Z:82 (= number of protons)Neutrons N:96Nucleon pairing (Z - N):even - evenNuclear ratio (N/Z ratio):1.1707317073171 (= neutron-proton ratio)Neutron excess (N-Z):14Isotopic mass:178.003836(25) u (atomic weight of Lead-178)Nuclide mass:177.9588576 u (calculated nuclear mass without electrons)Mass excess:3.57321 MeVMass defect:1.46964856 u (per nucleus)Nuclear binding energy:1368.96881575 MeV (per nucleus)
7.69083604 MeV (average binding energy per nucleon)Separation energy:
S_P = 0.375(32) MeV (first proton)Half-life:0.12(14) msDecay constant λ:5776.2265046662 s^-1Specific activity α:1.95422750842 × 10⁺²⁵ Bq g^-1
5.281695968721 × 10⁺¹⁴ Ci g^-1Spin and parity:
(nuclear angular momentum)0+Year of discovery:2001

Radioactive Decay

Half-life T_½ = 0.12(14) ms respectively 1.2 × 10^-4 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	¹⁷⁴Hg	100 %	7.789(13) MeV
β⁺ ?

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 96) and isobaric (same nucleon number A = 178) with Lead-178. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 96	Isobar A = 178
55	¹⁵¹Cs
56	¹⁵²Ba
57	¹⁵³La
58	¹⁵⁴Ce
59	¹⁵⁵Pr
60	¹⁵⁶Nd
61	¹⁵⁷Pm
62	¹⁵⁸Sm
63	¹⁵⁹Eu
64	¹⁶⁰Gd
65	¹⁶¹Tb
66	¹⁶²Dy
67	¹⁶³Ho
68	¹⁶⁴Er
69	¹⁶⁵Tm	¹⁷⁸Tm
70	¹⁶⁶Yb	¹⁷⁸Yb
71	¹⁶⁷Lu	¹⁷⁸Lu
72	¹⁶⁸Hf	¹⁷⁸Hf
73	¹⁶⁹Ta	¹⁷⁸Ta
74	¹⁷⁰W	¹⁷⁸W
75	¹⁷¹Re	¹⁷⁸Re
76	¹⁷²Os	¹⁷⁸Os
77	¹⁷³Ir	¹⁷⁸Ir
78	¹⁷⁴Pt	¹⁷⁸Pt
79	¹⁷⁵Au	¹⁷⁸Au
80	¹⁷⁶Hg	¹⁷⁸Hg
81	¹⁷⁷Tl	¹⁷⁸Tl
82	¹⁷⁸Pb	¹⁷⁸Pb