Isotopes of astatine

Astatine (At) has 37 known isotopes, all of which are radioactive; the range of their mass numbers is from 191 to 229. There exist also 23 metastable excited states. The longest-lived isotope is ²¹⁰At, which has a half-life of 8.1 hours; the longest-lived isotope existing in naturally occurring decay chains is ²¹⁹At with a half-life of 56 seconds.

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
191At	85	106		1.7(+11-5) ms			(1/2+)
191mAt				2.1(+4-3) ms			(7/2-)
193At	85	108	192.99984(6)	28(+5-4) ms	α	189Bi	(1/2+)
193m1At	50 keV			21(5) ms			(7/2-)
193m2At	39 keV			27(+4-5) ms			(13/2+)
194At	85	109	193.99873(20)	~40 ms	α	190Bi	3+#
					β+ (rare)	194Po
194mAt	480(190) keV			~250 ms	α	190Bi	10-#
					IT (rare)	194At
195At	85	110	194.996268(10)	328(20) ms	α (75%)	191Bi	(1/2+)
					β+ (25%)	195Po
195mAt	34(7) keV			147(5) ms			9/2-#
196At	85	111	195.99579(6)	253(9) ms	α (96%)	192Bi	3+#
					β+ (4%)	196Po
196m1At	-30(80) keV			20# ms			10-#
196m2At	157.9(1) keV			11 µs			5+#
197At	85	112	196.99319(5)	0.390(16) s	α (96%)	193Bi	(9/2-)
					β+ (4%)	197Po
197mAt	52(10) keV			2.0(2) s			(1/2+)
198At	85	113	197.99284(5)	4.2(3) s	α (94%)	194Bi	(3+)
					β+ (6%)	198Po
198mAt	330(90)# keV			1.0(2) s			(10-)
199At	85	114	198.99053(5)	6.92(13) s	α (89%)	195Bi	(9/2-)
					β+ (11%)	199Po
200At	85	115	199.990351(26)	43.2(9) s	α (57%)	196Bi	(3+)
					β+ (43%)	200Po
200m1At	112.7(30) keV			47(1) s	α (43%)	196Bi	(7+)
					IT	200At
					β+	200Po
200m2At	344(3) keV			3.5(2) s			(10-)
201At	85	116	200.988417(9)	85(3) s	α (71%)	197Bi	(9/2-)
					β+ (29%)	201Po
202At	85	117	201.98863(3)	184(1) s	β+ (88%)	202Po	(2,3)+
					α (12%)	198Bi
202m1At	190(40) keV			182(2) s			(7+)
202m2At	580(40) keV			460(50) ms			(10-)
203At	85	118	202.986942(13)	7.37(13) min	β+ (69%)	203Po	9/2-
					α (31%)	199Bi
204At	85	119	203.987251(26)	9.2(2) min	β+ (96.2%)	204Po	7+
					α (3.8%)	200Bi
204mAt	587.30(20) keV			108(10) ms	IT	204At	(10-)
205At	85	120	204.986074(16)	26.2(5) min	β+ (90%)	205Po	9/2-
					α (10%)	201Bi
205mAt	2339.65(23) keV			7.76(14) µs			29/2+
206At	85	121	205.986667(22)	30.6(13) min	β+ (99.11%)	206Po	(5)+
					α (.89%)	202Bi
206mAt	807(3) keV			410(80) ns			(10)-
207At	85	122	206.985784(23)	1.80(4) h	β+ (91.4%)	207Po	9/2-
					α (8.6%)	203Bi
208At	85	123	207.986590(28)	1.63(3) h	β+ (99.45%)	208Po	6+
					α (.55%)	204Bi
209At	85	124	208.986173(8)	5.41(5) h	β+ (95.9%)	209Po	9/2-
					α (4.1%)	205Bi
210At	85	125	209.987148(8)	8.1(4) h	β+ (99.82%)	210Po	(5)+
					α (.175%)	206Bi
210m1At	2549.6(2) keV			482(6) µs			(15)-
210m2At	4027.7(2) keV			5.66(7) µs			(19)+
211At	85	126	210.9874963(30)	7.214(7) h	EC (58.2%)	211Po	9/2-
					α (41.8%)	207Bi
212At	85	127	211.990745(8)	0.314(2) s	α (99.97%)	208Bi	(1-)
					β+ (.03%)	212Po
					β- (2×10−6%)	212Rn
212m1At	223(7) keV			0.119(3) s	α (99%)	208Bi	(9-)
					IT (1%)	212At
212m2At	4771.6(11) keV			152(5) µs			(25-)
213At	85	128	212.992937(5)	125(6) ns	α	209Bi	9/2-
214At	85	129	213.996372(5)	558(10) ns	α	210Bi	1-
214m1At	59(9) keV			265(30) ns
214m2At	231(6) keV			760(15) ns			9-
215At	85	130	214.998653(7)	0.10(2) ms	α	211Bi	9/2-	Trace
216At	85	131	216.002423(4)	0.30(3) ms	α (99.99%)	212Bi	1-
					β- (.006%)	216Rn
					EC (3×10−7%)	216Po
216mAt	413(5) keV			100# µs			(9-)
217At	85	132	217.004719(5)	32.3(4) ms	α (99.98%)	213Bi	9/2-
					β- (.012%)	217Rn
218At	85	133	218.008694(12)	1.5(3) s	α (99.9%)	214Bi	1-#	Trace
					β- (.1%)	218Rn
219At	85	134	219.011162(4)	56(3) s	α (97%)	215Bi	5/2-#	Trace
					β- (3%)	219Rn
220At	85	135	220.01541(6)	3.71(4) min	β- (92%)	220Rn	3(-#)
					α (8%)	216Bi
221At	85	136	221.01805(21)#	2.3(2) min	β-	221Rn	3/2-#
222At	85	137	222.02233(32)#	54(10) s	β-	222Rn
223At	85	138	223.02519(43)#	50(7) s			3/2-#

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.

References

• Isotope masses from:
  • G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties". Nuclear Physics A 729: 3–128. Bibcode 2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf. 
• 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 and 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. http://www.iupac.org/publications/pac/75/6/0683/pdf/. 
  • 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. http://iupac.org/publications/pac/78/11/2051/pdf/. 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 and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties". Nuclear Physics A 729: 3–128. Bibcode 2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf. 
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. http://www.nndc.bnl.gov/nudat2/. 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 978-0849304859. 

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