Isotopes of arsenic

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Although arsenic (As) has multiple isotopes, only one of these isotopes is stable; as such, it is considered a monoisotopic element.
Standard atomic mass: 74.92160(2) u

[edit] 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
60As	33	27	59.99313(64)#		5+#
61As	33	28	60.98062(64)#		3/2-#
62As	33	29	61.97320(32)#		1+#
63As	33	30	62.96369(54)#		(3/2-)#
64As	33	31	63.95757(38)#	40(30) ms [18(+43-7) ms]	0+#
65As	33	32	64.94956(32)#	170(30) ms	3/2-#
66As	33	33	65.94471(73)	95.77(23) ms	(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	(5/2-)
68As	33	35	67.93677(5)	151.6(8) s	3+
68mAs	425.21(16) keV			111(20) s [?107(+23-16) ns]	1+
69As	33	36	68.93227(3)	15.2(2) min	5/2-
70As	33	37	69.93092(5)	52.6(3) min	4(+#)
70mAs	32.008(23) keV			96(3) µs	2(+)
71As	33	38	70.927112(5)	65.28(15) h	5/2-
72As	33	39	71.926752(5)	26.0(1) h	2-
73As	33	40	72.923825(4)	80.30(6) d	3/2-
74As	33	41	73.9239287(25)	17.77(2) d	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	2-
76mAs	44.425(1) keV			1.84(6) µs	(1)+
77As	33	44	76.9206473(25)	38.83(5) h	3/2-
77mAs	475.443(16) keV			114.0(25) µs	9/2+
78As	33	45	77.921827(11)	90.7(2) min	2-
79As	33	46	78.920948(6)	9.01(15) min	3/2-
79mAs	772.81(6) keV			1.21(1) µs	(9/2)+
80As	33	47	79.922534(25)	15.2(2) s	1+
81As	33	48	80.922132(6)	33.3(8) s	3/2-
82As	33	49	81.92450(21)	19.1(5) s	(1+)
82mAs	250(200) keV			13.6(4) s	(5-)
83As	33	50	82.92498(24)	13.4(3) s	3/2-#
84As	33	51	83.92906(32)#	4.02(3) s	(3)(+#)
84mAs	0(100)# keV			650(150) ms
85As	33	52	84.93202(21)#	2.021(10) s	(3/2-)#
86As	33	53	85.93650(32)#	0.945(8) s
87As	33	54	86.93990(32)#	0.56(8) s	3/2-#
88As	33	55	87.94494(54)#	300# ms [>300 ns]
89As	33	56	88.94939(54)#	200# ms [>300 ns]	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]

[edit] 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.

[edit] 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.

Isotopes of germanium	Isotopes of arsenic	Isotopes of selenium
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