Isotopes of arsenic

Arsenic (As) has 33 known isotopes and at least 10 isomers. Only one of these isotopes, ⁷⁵As, is stable; as such, it is considered a monoisotopic element. The longest-lived radioisotope is ⁷³As has a half-life of 80 days. Arsenic has been proposed as a "salting" material for nuclear weapons (cobalt is another, better-known salting material). A jacket of ⁷⁵As, irradiated by the intense highenergy neutron flux from an exploding thermonuclear weapon, would transmute into the radioactive isotope ⁷⁶As with a half-life of 1.0778 days and produce approximately 1.13 MeV gamma radiation, significantly increasing the radioactivity of the weapon's fallout for several hours. Such a weapon is not known to have ever been built, tested, or used.

Relative atomic mass: 74.92160(2)

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)^[1]^{[n 1]}	daughter isotope(s)^{[n 2]}	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
nuclide symbol	excitation energy			half-life	decay mode(s)^[1]^{[n 1]}	daughter isotope(s)^{[n 2]}	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
⁶⁰As	33	27	59.99313(64)#		p	⁵⁹Ge	5+#
⁶¹As	33	28	60.98062(64)#		p	⁶⁰Ge	3/2−#
⁶²As	33	29	61.97320(32)#		p	⁶¹Ge	1+#
⁶³As	33	30	62.96369(54)#		p	⁶²Ge	(3/2−)#
⁶⁴As	33	31	63.95757(38)#	40(30) ms [18(+43-7) ms]	β⁺	⁶⁴Ge	0+#
⁶⁵As	33	32	64.94956(32)#	170(30) ms	β⁺	⁶⁵Ge	3/2−#
⁶⁶As	33	33	65.94471(73)	95.77(23) ms	β⁺	⁶⁶Ge	(0+)
^66m1As	1356.70(17) keV			1.1(1) µs			(5+)
^66m2As	3023.9(3) keV			8.2(5) µs			(9+)
⁶⁷As	33	34	66.93919(11)	42.5(12) s	β⁺	⁶⁷Ge	(5/2−)
⁶⁸As	33	35	67.93677(5)	151.6(8) s	β⁺	⁶⁸Ge	3+
^68mAs	425.21(16) keV			111(20) ns [?107(+23-16) ns]			1+
⁶⁹As	33	36	68.93227(3)	15.2(2) min	β⁺	⁶⁹Ge	5/2−
⁷⁰As	33	37	69.93092(5)	52.6(3) min	β⁺	⁷⁰Ge	4(+#)
^70mAs	32.008(23) keV			96(3) µs			2(+)
⁷¹As	33	38	70.927112(5)	65.28(15) h	β⁺	⁷¹Ge	5/2−
⁷²As	33	39	71.926752(5)	26.0(1) h	β⁺	⁷²Ge	2−
⁷³As	33	40	72.923825(4)	80.30(6) d	EC	⁷³Ge	3/2−
⁷⁴As	33	41	73.9239287(25)	17.77(2) d	β⁺ (66%)	⁷⁴Ge	2−
⁷⁴As	33	41	73.9239287(25)	17.77(2) d	β⁻ (34%)	⁷⁴Se	2−
⁷⁵As	33	42	74.9215965(20)	Stable			3/2−	1.0000
^75mAs	303.9241(7) keV			17.62(23) ms			9/2+
⁷⁶As	33	43	75.922394(2)	1.0942(7) d	β⁻ (99.98%)	⁷⁶Se	2−
⁷⁶As	33	43	75.922394(2)	1.0942(7) d	EC (.02%)	⁷⁶Ge	2−
^76mAs	44.425(1) keV			1.84(6) µs			(1)+
⁷⁷As	33	44	76.9206473(25)	38.83(5) h	β⁻	^77mSe	3/2−
^77mAs	475.443(16) keV			114.0(25) µs			9/2+
⁷⁸As	33	45	77.921827(11)	90.7(2) min	β⁻	⁷⁸Se	2−
⁷⁹As	33	46	78.920948(6)	9.01(15) min	β⁻	^79mSe	3/2−
^79mAs	772.81(6) keV			1.21(1) µs			(9/2)+
⁸⁰As	33	47	79.922534(25)	15.2(2) s	β⁻	⁸⁰Se	1+
⁸¹As	33	48	80.922132(6)	33.3(8) s	β⁻	^81mSe	3/2−
⁸²As	33	49	81.92450(21)	19.1(5) s	β⁻	⁸²Se	(1+)
^82mAs	250(200) keV			13.6(4) s	β⁻	⁸²Se	(5-)
⁸³As	33	50	82.92498(24)	13.4(3) s	β⁻	^83mSe	3/2−#
⁸⁴As	33	51	83.92906(32)#	4.02(3) s	β⁻ (99.721%)	⁸⁴Se	(3)(+#)
⁸⁴As	33	51	83.92906(32)#	4.02(3) s	β⁻, n (.029%)	⁸³Se	(3)(+#)
^84mAs	0(100)# keV			650(150) ms
⁸⁵As	33	52	84.93202(21)#	2.021(10) s	β⁻, n (59.4%)	⁸⁴Se	(3/2−)#
⁸⁵As	33	52	84.93202(21)#	2.021(10) s	β⁻ (40.6%)	⁸⁵Se	(3/2−)#
⁸⁶As	33	53	85.93650(32)#	0.945(8) s	β⁻ (67%)	⁸⁶Se
⁸⁶As	33	53	85.93650(32)#	0.945(8) s	β⁻, n (33%)	⁸⁵Se
⁸⁷As	33	54	86.93990(32)#	0.56(8) s	β⁻ (84.6%)	⁸⁷Se	3/2−#
⁸⁷As	33	54	86.93990(32)#	0.56(8) s	β⁻, n (15.4%)	⁸⁶Se	3/2−#
⁸⁸As	33	55	87.94494(54)#	300# ms [>300 ns]	β⁻	⁸⁸Se
⁸⁸As	33	55	87.94494(54)#	300# ms [>300 ns]	β⁻, n	⁸⁷Se
⁸⁹As	33	56	88.94939(54)#	200# ms [>300 ns]	β⁻	⁸⁹Se	3/2−#
⁹⁰As	33	57	89.95550(86)#	80# ms [>300 ns]
⁹¹As	33	58	90.96043(97)#	50# ms [>300 ns]			3/2−#
⁹²As	33	59	91.96680(97)#	30# ms [>300 ns]

↑ Abbreviations:
EC: Electron capture
↑ Bold for stable isotopes, bold italic for nearly-stable isotopes (half-life longer than the age of the universe)

Notes

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.

Notes

↑ "Universal Nuclide Chart". nucleonica. (registration required (help)).

References

Isotope masses from:
- G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillo (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 (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry 78 (11): 2051–2066. doi:10.1351/pac200678112051. 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. Bersillo (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.

A.Shore, A. Fritsch, M. Heim, A. Schuh, M. Thoennessen. Discovery of the Arsenic Isotopes. arXiv:0902.4361.

Isotopes of germanium	Isotopes of arsenic	Isotopes of selenium
Table of nuclides

Isotopes of the chemical elements
1 H																	2 He
3 Li	4 Be											5 B	6 C	7 N	8 O	9 F	10 Ne
11 Na	12 Mg											13 Al	14 Si	15 P	16 S	17 Cl	18 Ar
19 K	20 Ca	21 Sc	22 Ti	23 V	24 Cr	25 Mn	26 Fe	27 Co	28 Ni	29 Cu	30 Zn	31 Ga	32 Ge	33 As	34 Se	35 Br	36 Kr
37 Rb	38 Sr	39 Y	40 Zr	41 Nb	42 Mo	43 Tc	44 Ru	45 Rh	46 Pd	47 Ag	48 Cd	49 In	50 Sn	51 Sb	52 Te	53 I	54 Xe
55 Cs	56 Ba		72 Hf	73 Ta	74 W	75 Re	76 Os	77 Ir	78 Pt	79 Au	80 Hg	81 Tl	82 Pb	83 Bi	84 Po	85 At	86 Rn
87 Fr	88 Ra		104 Rf	105 Db	106 Sg	107 Bh	108 Hs	109 Mt	110 Ds	111 Rg	112 Cn	113 Uut	114 Fl	115 Uup	116 Lv	117 Uus	118 Uuo

		57 La	58 Ce	59 Pr	60 Nd	61 Pm	62 Sm	63 Eu	64 Gd	65 Tb	66 Dy	67 Ho	68 Er	69 Tm	70 Yb	71 Lu
		89 Ac	90 Th	91 Pa	92 U	93 Np	94 Pu	95 Am	96 Cm	97 Bk	98 Cf	99 Es	100 Fm	101 Md	102 No	103 Lr
Table of nuclides Categories: Isotopes Tables of nuclides Metastable isotopes Isotopes by element

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