Isotopes of molybdenum

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.^[1]

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.^[1]

Relative atomic mass: 95.95(1).^[2]

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life[n 1]	decay mode(s)[3][n 2]	daughter isotope(s)[n 3]	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[n 4]			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[n 5]			0+	0.09187(33)
^95Mo[n 6]	42	53	94.9058421(21)	Stable[n 5]			5/2+	0.15873(30)
^96Mo	42	54	95.9046795(21)	Stable[n 5]			0+	0.16673(30)
^97Mo[n 6]	42	55	96.9060215(21)	Stable[n 5]			5/2+	0.09582(15)
^98Mo[n 6]	42	56	97.9054082(21)	Observationally Stable[n 7]			0+	0.24292(80)
^99Mo[n 6][n 8]	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[n 9][n 6]	42	58	99.907477(6)	8.5(5)×10^18 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]

1. Bold for isotopes with half-lives longer than the age of the universe (nearly stable)
2. Abbreviations:
   EC: Electron capture
   IT: Isomeric transition
3. Bold for stable isotopes
4. Believed to decay by β⁺β⁺ to ⁹²Zr with a half-life over 1.9×10²⁰ years
5. Believed to be capable of spontaneous fission
6. Fission product
7. Believed to decay by β⁻β⁻ to ⁹⁸Ru with a half-life of over 1×10¹⁴ years
8. Used to produce the medically useful radioisotope technetium-99m
9. Primordial radionuclide

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.^[4] 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

1. D. R. Lide, ed. (2006). CRC Handbook of Chemistry and Physics 11. CRC Press. pp. 87–88. ISBN 0-8493-0487-3.
2. "Standard Atomic Weights 2013". Commission on Isotopic Abundances and Atomic Weights.
3. "Universal Nuclide Chart". nucleonica. (registration required (help)).
4. Frank N. Von Hippel; Laura H. Kahn (December 2006). "Feasibility of Eliminating the Use of Highly Enriched Uranium in the Production of Medical Radioisotopes". Science & Global Security 14 (2 & 3): 151–162. doi:10.1080/08929880600993071. Retrieved 2010-03-26.

• Isotope masses from:
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
• Isotopic compositions and standard atomic masses from:
  • J. R. de Laeter; J. K. Böhlke; P. De Bièvre; H. Hidaka; H. S. Peiser; K. J. R. Rosman; P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry 75 (6): 683–800. doi:10.1351/pac200375060683.
  • M. E. Wieser; M. Berglund (2009). "Atomic weights of the elements 2007 (IUPAC Technical Report)" (PDF). Pure and Applied Chemistry 81 (11): 2131–2156. doi:10.1351/PAC-REP-09-08-03. Lay summary.
• Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005.
  • N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0-8493-0485-9.