Tungsten-187

Properties and data of the isotope ¹⁸⁷W.

Contents

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

General data

Name of the isotope:Tungsten-187; W-187Symbol:¹⁸⁷W or 18774WMass number A:187 (= number of nucleons)Atomic number Z:74 (= number of protons)Neutrons N:113Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.527027027027 (= neutron-proton ratio)Neutron excess (N-Z):39Isotopic mass:186.9571613(13) u (atomic weight of Tungsten-187)Nuclide mass:186.9165704 u (calculated nuclear mass without electrons)Mass excess:-39.90399 MeVMass defect:1.601026576 u (per nucleus)Nuclear binding energy:1491.34664938 MeV (per nucleus)
7.97511577 MeV (average binding energy per nucleon)Separation energy:S_N = 5.46676(4) MeV (first neutron)
S_P = 8.59(6) MeV (first proton)Half-life:23.72(6) hDecay constant λ:8.117237921116 × 10^-6 s^-1Specific activity α:2.628126352396 × 10⁺¹⁶ Bq g^-1
710304.4195667 Ci g^-1Spin and parity:
(nuclear angular momentum)3/2-Magnetic dipole moment:μ(μ_N) = 0.621(15)Nuclear g-factor:g_l = 0.414Year of discovery:1940

Radioactive Decay

Half-life T_½ = 23.72(6) h (hours) respectively 8.5392 × 10⁴ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹⁸⁷Re	100 %	1.3125(11) MeV

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 113) and isobaric (same nucleon number A = 187) with Tungsten-187. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 113	Isobar A = 187
70	¹⁸³Yb
71	¹⁸⁴Lu	¹⁸⁷Lu
72	¹⁸⁵Hf	¹⁸⁷Hf
73	¹⁸⁶Ta	¹⁸⁷Ta
74	¹⁸⁷W	¹⁸⁷W
75	¹⁸⁸Re	¹⁸⁷Re
76	¹⁸⁹Os	¹⁸⁷Os
77	¹⁹⁰Ir	¹⁸⁷Ir
78	¹⁹¹Pt	¹⁸⁷Pt
79	¹⁹²Au	¹⁸⁷Au
80	¹⁹³Hg	¹⁸⁷Hg
81	¹⁹⁴Tl	¹⁸⁷Tl
82	¹⁹⁵Pb	¹⁸⁷Pb
83	¹⁹⁶Bi	¹⁸⁷Bi
84	¹⁹⁷Po	¹⁸⁷Po
85	¹⁹⁸At
86	¹⁹⁹Rn
87	²⁰⁰Fr
88	²⁰¹Ra