Isotopes of molybdenum

For MO99 Freon mix R438A, see Refrigerant.

There are 33 known isotopes of molybdenum (Mo) ranging in atomic mass from 83 to 115, 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, six (all but ¹⁰⁰Mo) have never been observed to decay, but all are theoretically capable of radioactive decay. All unstable isotopes of molybdenum decay into isotopes of zirconium, niobium, technetium, and ruthenium.

Molybdenum-100 is the only naturally occurring isotope that is 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 on Earth. Molybdenum isotopes with mass numbers 111 and up all have half-lives of approximately .15 µs.

Relative atomic mass: 95.95(1).

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)	daughter isotope(s)	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]	β+	83Nb	3/2−#
					β+, p	82Zr
84Mo	42	42	83.94009(43)#	3.8(9) ms [3.7(+10-8) s]	β+	84Nb	0+
85Mo	42	43	84.93655(30)#	3.2(2) s	β+	85Nb	(1/2−)#
86Mo	42	44	85.93070(47)	19.6(11) s	β+	86Nb	0+
87Mo	42	45	86.92733(24)	14.05(23) s	β+ (85%)	87Nb	7/2+#
					β+, p (15%)	86Zr
88Mo	42	46	87.921953(22)	8.0(2) min	β+	88Nb	0+
89Mo	42	47	88.919480(17)	2.11(10) min	β+	89Nb	(9/2+)
89mMo	387.5(2) keV			190(15) ms	IT	89Mo	(1/2−)
90Mo	42	48	89.913937(7)	5.56(9) h	β+	90Nb	0+
90mMo	2874.73(15) keV			1.12(5) µs			8+#
91Mo	42	49	90.911750(12)	15.49(1) min	β+	91Nb	9/2+
91mMo	653.01(9) keV			64.6(6) s	IT (50.1%)	91Mo	1/2−
					β+ (49.9%)	91Nb
92Mo	42	50	91.906811(4)	Observationally Stable			0+	0.14649(106)
92mMo	2760.46(16) keV			190(3) ns			8+
93Mo	42	51	92.906813(4)	4,000(800) y	EC	93Nb	5/2+
93mMo	2424.89(3) keV			6.85(7) h	IT (99.88%)	93Mo	21/2+
					β+ (.12%)	93Nb
94Mo	42	52	93.9050883(21)	Stable			0+	0.09187(33)
95Mo	42	53	94.9058421(21)	Stable			5/2+	0.15873(30)
96Mo	42	54	95.9046795(21)	Stable			0+	0.16673(30)
97Mo	42	55	96.9060215(21)	Stable			5/2+	0.09582(15)
98Mo	42	56	97.9054082(21)	Observationally Stable			0+	0.24292(80)
99Mo	42	57	98.9077119(21)	2.7489(6) d	β−	99mTc	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)×1018 a	β−β−	100Ru	0+	0.09744(65)
101Mo	42	59	100.910347(6)	14.61(3) min	β−	101Tc	1/2+
102Mo	42	60	101.910297(22)	11.3(2) min	β−	102Tc	0+
103Mo	42	61	102.91321(7)	67.5(15) s	β−	103Tc	(3/2+)
104Mo	42	62	103.91376(6)	60(2) s	β−	104Tc	0+
105Mo	42	63	104.91697(8)	35.6(16) s	β−	105Tc	(5/2−)
106Mo	42	64	105.918137(19)	8.73(12) s	β−	106Tc	0+
107Mo	42	65	106.92169(17)	3.5(5) s	β−	107Tc	(7/2−)
107mMo	66.3(2) keV			470(30) ns			(5/2−)
108Mo	42	66	107.92345(21)#	1.09(2) s	β−	108Tc	0+
109Mo	42	67	108.92781(32)#	0.53(6) s	β−	109Tc	(7/2−)#
110Mo	42	68	109.92973(43)#	0.27(1) s	β− (>99.9%)	110Tc	0+
					β−, n (<.1%)	109Tc
111Mo	42	69	110.93441(43)#	200# ms [>300 ns]	β−	111Tc
112Mo	42	70	111.93684(64)#	150# ms [>300 ns]	β−	112Tc	0+
113Mo	42	71	112.94188(64)#	100# ms [>300 ns]	β−	113Tc
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.

Applications

Molybdenum-99 is produced commercially by intense neutron-bombardment of a highly purified uranium-235 target, followed rapidly by extraction. It is used as a parent radioisotope in technetium-99m generators to produce the even shorter-lived daughter isotope technetium-99m, which is used in many medical procedures.

References

• Isotope masses from:
• Isotopic compositions and standard atomic masses from:
• Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.

Isotopes of niobium	Isotopes of molybdenum	Isotopes of technetium
Table of nuclides