Isotopes of molybdenum

There are 35 known isotopes of molybdenum (Mo) ranging in atomic mass from 83 to 117, as well as four metastable nuclear isomers. Seven isotopes occur naturally, with atomic masses of 92, 94, 95, 96, 97, 98, and 100. Of these naturally occurring isotopes, five are stable, with atomic masses from 94 to 98. All unstable isotopes of molybdenum decay into isotopes of niobium, technetium, and ruthenium.

Molybdenum-92 and molybdenum-100 are the only naturally occurring isotopes which are not stable. Molybdenum-100 has a half-life of approximately 1×10¹⁹ y and undergoes double beta decay into ruthenium-100. Molybdenum-98 is the most common isotope, comprising 24.14% of all molybdenum. Molybdenum isotopes with mass numbers from 111 to 117 all have half-lives of approximately .15 μs.
Standard atomic mass: 95.94(2) u

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
	excitation energy
83Mo	42	41	82.94874(54)#	23(19) ms [6(+30-3) ms]	3/2-#
84Mo	42	42	83.94009(43)#	3.8(9) ms [3.7(+10-8) s]	0+
85Mo	42	43	84.93655(30)#	3.2(2) s	(1/2-)#
86Mo	42	44	85.93070(47)	19.6(11) s	0+
87Mo	42	45	86.92733(24)	14.05(23) s	7/2+#
88Mo	42	46	87.921953(22)	8.0(2) min	0+
89Mo	42	47	88.919480(17)	2.11(10) min	(9/2+)
89mMo	387.5(2) keV			190(15) ms	(1/2-)
90Mo	42	48	89.913937(7)	5.56(9) h	0+
90mMo	2874.73(15) keV			1.12(5) µs	8+#
91Mo	42	49	90.911750(12)	15.49(1) min	9/2+
91mMo	653.01(9) keV			64.6(6) s	1/2-
92Mo	42	50	91.906811(4)	STABLE [>190E+18 a]	0+	0.1477(31)
92mMo	2760.46(16) keV			190(3) ns	8+
93Mo	42	51	92.906813(4)	4.0(8)E+3 a	5/2+
93mMo	2424.89(3) keV			6.85(7) h	21/2+
94Mo	42	52	93.9050883(21)	STABLE	0+	0.0923(10)
95Mo	42	53	94.9058421(21)	STABLE	5/2+	0.1590(9)
96Mo	42	54	95.9046795(21)	STABLE	0+	0.1668(1)
97Mo	42	55	96.9060215(21)	STABLE	5/2+	0.0956(5)
98Mo	42	56	97.9054082(21)	STABLE [>100E+12 a]	0+	0.2419(26)
99Mo	42	57	98.9077119(21)	2.7489(6) d	1/2+
99m1Mo	97.785(3) keV			15.5(2) µs	5/2+
99m2Mo	684.5(4) keV			0.76(6) µs	11/2-
100Mo	42	58	99.907477(6)	8.5(5)E+18 a	0+	0.0967(20)
101Mo	42	59	100.910347(6)	14.61(3) min	1/2+
102Mo	42	60	101.910297(22)	11.3(2) min	0+
103Mo	42	61	102.91321(7)	67.5(15) s	(3/2+)
104Mo	42	62	103.91376(6)	60(2) s	0+
105Mo	42	63	104.91697(8)	35.6(16) s	(5/2-)
106Mo	42	64	105.918137(19)	8.73(12) s	0+
107Mo	42	65	106.92169(17)	3.5(5) s	(7/2-)
107mMo	66.3(2) keV			470(30) ns	(5/2-)
108Mo	42	66	107.92345(21)#	1.09(2) s	0+
109Mo	42	67	108.92781(32)#	0.53(6) s	(7/2-)#
110Mo	42	68	109.92973(43)#	0.27(1) s	0+
111Mo	42	69	110.93441(43)#	200# ms [>300 ns]
112Mo	42	70	111.93684(64)#	150# ms [>300 ns]	0+
113Mo	42	71	112.94188(64)#	100# ms [>300 ns]
114Mo	42	72	113.94492(75)#	80# ms [>300 ns]	0+
115Mo	42	73	114.95029(86)#	60# ms [>300 ns]

Notes

• Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.
• Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
• Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.

References

• Isotope masses from Ame2003 Atomic Mass Evaluation by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in Nuclear Physics A729 (2003).
• Isotopic compositions and standard atomic masses from Atomic weights of the elements. Review 2000 (IUPAC Technical Report). Pure Appl. Chem. Vol. 75, No. 6, pp. 683-800, (2003) and Atomic Weights Revised (2005).
• Half-life, spin, and isomer data selected from these sources. Editing notes on this article's talk page.
  • Audi, Bersillon, Blachot, Wapstra. The Nubase2003 evaluation of nuclear and decay properties, Nuc. Phys. A 729, pp. 3-128 (2003).
  • National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the NuDat 2.1 database (retrieved Sept. 2005).
  • David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition, online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.