Isotopes of radon

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There are thirty four known isotopes of radon (Rn). The most stable isotope is ²²²Rn, which is a decay product (daughter product) of ²²⁶Ra, has a half-life of 3.823 days and emits alpha particles. ²²⁰Rn is a natural decay product of thorium and is called “thoron.” It has a half-life of 55.6 seconds and also emits alpha radiation. ²¹⁹Rn is derived from actinium, is called “actinon,” is an alpha emitter and has a half-life of 3.96 seconds.

Contents 1 Decay chain 2 Older nomenclature 3 Table 3.1 Notes 4 References

[edit] Decay chain

The full decay series of ²³⁸U which produces natural radon is as follows (with half-lives):

²³⁸U (4.5 x 10⁹ yr), ²³⁴Th (24.1 days), ²³⁴Pa (1.18 min), ²³⁴U (2.457 x 10⁵ yr), ²³⁰Th (75,000 yr), ²²⁶Ra (1,600 yr), ²²²Rn (3.82 days), ²¹⁸Po (3.1 min), ²¹⁴Pb (26.8 min), ²¹⁴Bi (19.7 min), ²¹⁴Po (164 µs), ²¹⁰Pb (22.3 yr), ²¹⁰Bi (5.01 days), ²¹⁰Po (138 days), ²⁰⁶Pb (stable).

[edit] Older nomenclature

Isotopes of radon occurring within the radioactive disintegration chains of actinium, radium and thorium were known as:

• actinon or actinium emanation : ²¹⁹Rn
• thoron or thorium emanation : ²²⁰Rn
• radon or radium emanation, emanation, emanon, or niton : ²²²Rn

[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
195Rn	86	109	195.00544(5)	6 ms	3/2-#
195mRn	50(50) keV			6 ms	13/2+#
196Rn	86	110	196.002115(16)	4.7(11) ms [4.4(+13-9) ms]	0+
197Rn	86	111	197.00158(7)	66(16) ms [65(+25-14) ms]	3/2-#
197mRn	200(60)# keV			21(5) ms [19(+8-4) ms]	(13/2+)
198Rn	86	112	197.998679(14)	65(3) ms	0+
199Rn	86	113	198.99837(7)	620(30) ms	3/2-#
199mRn	180(70) keV			320(20) ms	13/2+#
200Rn	86	114	199.995699(14)	0.96(3) s	0+
201Rn	86	115	200.99563(8)	7.0(4) s	(3/2-)
201mRn	280(90)# keV			3.8(1) s	(13/2+)
202Rn	86	116	201.993263(19)	9.94(18) s	0+
203Rn	86	117	202.993387(25)	44.2(16) s	(3/2-)
203mRn	363(4) keV			26.7(5) s	13/2(+)
204Rn	86	118	203.991429(16)	1.17(18) min	0+
205Rn	86	119	204.99172(5)	170(4) s	5/2-
206Rn	86	120	205.990214(16)	5.67(17) min	0+
207Rn	86	121	206.990734(28)	9.25(17) min	5/2-
207mRn	899.0(10) keV			181(18) µs	(13/2+)
208Rn	86	122	207.989642(12)	24.35(14) min	0+
209Rn	86	123	208.990415(21)	28.5(10) min	5/2-
209m1Rn	1173.98(13) keV			13.4(13) µs	13/2+
209m2Rn	3636.78(23) keV			3.0(3) µs	(35/2+)
210Rn	86	124	209.989696(9)	2.4(1) h	0+
210m1Rn	1690(15) keV			644(40) ns	8+#
210m2Rn	3837(15) keV			1.06(5) µs	(17)-
210m3Rn	6493(15) keV			1.04(7) µs	(22)+
211Rn	86	125	210.990601(7)	14.6(2) h	1/2-
212Rn	86	126	211.990704(3)	23.9(12) min	0+
213Rn	86	127	212.993883(6)	19.5(1) ms	(9/2+)
214Rn	86	128	213.995363(10)	0.27(2) µs	0+
214mRn	4595.4 keV			245(30) ns	(22+)
215Rn	86	129	214.998745(8)	2.30(10) µs	9/2+
216Rn	86	130	216.000274(8)	45(5) µs	0+
217Rn	86	131	217.003928(5)	0.54(5) ms	9/2+
218Rn	86	132	218.0056013(25)	35(5) ms	0+
219Rn	86	133	219.0094802(27)	3.96(1) s	5/2+
220Rn	86	134	220.0113940(24)	55.6(1) s	0+
221Rn	86	135	221.015537(6)	25.7(5) min	7/2(+)
222Rn	86	136	222.0175777(25)	3.8235(3) d	0+
223Rn	86	137	223.02179(32)#	24.3(4) min	7/2
224Rn	86	138	224.02409(32)#	107(3) min	0+
225Rn	86	139	225.02844(32)#	4.66(4) min	7/2-
226Rn	86	140	226.03089(43)#	7.4(1) min	0+
227Rn	86	141	227.03541(45)#	20.8(7) s	5/2(+#)
228Rn	86	142	228.03799(44)#	65(2) s	0+

[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.

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