Thallium

Thallium

Thallium is a chemical element with the symbol Tl and atomic number 81. This soft gray poor metal resembles tin but discolors when exposed to air. The two chemists William Crookes and Claude-Auguste Lamy discovered thallium independently in 1861 by the newly developed method of flame spectroscopy...

(Tl) has 37 isotope

Isotope

Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...

s which have atomic mass

Atomic mass

The atomic mass is the mass of a specific isotope, most often expressed in unified atomic mass units. The atomic mass is the total mass of protons, neutrons and electrons in a single atom....

es that range from 176 to 212. ²⁰³Tl and ²⁰⁵Tl are the only stable isotopes and ²⁰⁴Tl is the most stable radioisotope with a half-life

Half-life

Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...

 of 3.78 years. ²⁰⁷Tl, with a half-life of 4.77 minutes, has the longest half-life of naturally occurring radioisotopes.

Thallium-202 (half-life 12.23 days) can be made in a cyclotron while thallium-204 (half-life 3.78 years) is made by the neutron activation

Neutron activation

Neutron activation is the process in which neutron radiation induces radioactivity in materials, and occurs when atomic nuclei capture free neutrons, becoming heavier and entering excited states. The excited nucleus often decays immediately by emitting particles such as neutrons, protons, or alpha...

 of stable thallium in a nuclear reactor

Nuclear reactor

A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid , which runs through turbines that power either ship's...

.

Standard atomic mass: 204.3833(2) u

Table

nuclide symbol	historic name	Z(p Proton The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number.... )	N(n Neutron The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of... )	isotopic mass (u)	half-life	decay mode(s)Abbreviations: EC: Electron capture Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... IT: Isomeric transition Isomeric transition An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer....	daughter isotope(s)Bold for stable isotopes	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
		excitation energy
176Tl		81	95	176.00059(21)#	5.2(+30-14) ms			(3-,4-,5-)
177Tl		81	100	176.996427(27)	18(5) ms	p Proton emission Proton emission is a type of radioactive decay in which a proton is ejected from a nucleus. Proton emission can occur from high-lying excited states in a nucleus following a beta decay, in which case the process is known as beta-delayed proton emission, or can occur from the ground state of very...	176Hg	(1/2+)
						α Alpha decay Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle and thereby transforms into an atom with a mass number 4 less and atomic number 2 less...  (rare)	173Au
177mTl		807(18) keV			230(40) µs	p	176Hg	(11/2-)
						α	173Au
178Tl		81	97	177.99490(12)#	255(10) ms	α	174Au
						p (rare)	177Hg
179Tl		81	98	178.99109(5)	270(30) ms	α	175Au	(1/2+)
						p (rare)	178Hg
179mTl		860(30)# keV			1.60(16) ms	α	175Au	(9/2-)
						IT Isomeric transition An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer....  (rare)	179Tl
180Tl		81	99	179.98991(13)#	1.5(2) s	α (75%)	176Au
						β+ Beta decay In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a...  (25%)	180Hg
						β+, 80Kr (10−4%)	100Ru, 80Kr
181Tl		81	100	180.986257(10)	3.2(3) s	α	177Au	1/2+#
						β+	181Hg
181mTl		857(29) keV			1.7(4) ms	α	177Au	9/2-#
						β+	181Hg
182Tl		81	101	181.98567(8)	2.0(3) s	β+ (96%)	182Hg	2-#
						α (4%)	178Au
182m1Tl		100(100)# keV			2.9(5) s	α	178Au	(7+)
						β+ (rare)	182Hg
182m2Tl		600(140)# keV						10-
183Tl		81	102	182.982193(10)	6.9(7) s	β+ (98%)	183Hg	1/2+#
						α (2%)	179Au
183m1Tl		630(17) keV			53.3(3) ms	IT (99.99%)	183Tl	9/2-#
						α (.01%)	179Au
183m2Tl		976.8(3) keV			1.48(10) µs			(13/2+)
184Tl		81	103	183.98187(5)	9.7(6) s	β+	184Hg	2-#
184m1Tl		100(100)# keV			10# s	β+ (97.9%)	184Hg	7+#
						α (2.1%)	180Au
184m2Tl		500(140)# keV			>20 ns			(10-)
185Tl		81	104	184.97879(6)	19.5(5) s	α	181Au	1/2+#
						β+	185Hg
185mTl		452.8(20) keV			1.93(8) s	IT (99.99%)	185Tl	9/2-#
						α (.01%)	181Au
						β+	185Hg
186Tl		81	105	185.97833(20)	40# s	β+	186Hg	(2-)
						α (.006%)	182Au
186m1Tl		320(180) keV			27.5(10) s	β+	186Hg	(7+)
186m2Tl		690(180) keV			2.9(2) s			(10-)
187Tl		81	106	186.975906(9)	~51 s	β+	187Hg	(1/2+)
						α (rare)	183Au
187mTl		335(3) keV			15.60(12) s	α	183Au	(9/2-)
						IT	187Tl
						β+	187Hg
188Tl		81	107	187.97601(4)	71(2) s	β+	188Hg	(2-)
188m1Tl		40(30) keV			71(1) s	β+	188Hg	(7+)
188m2Tl		310(30) keV			41(4) ms			(9-)
189Tl		81	108	188.973588(12)	2.3(2) min	β+	189Hg	(1/2+)
189mTl		257.6(13) keV			1.4(1) min	β+ (96%)	189Hg	(9/2-)
						IT (4%)	189Tl
190Tl		81	109	189.97388(5)	2.6(3) min	β+	190Hg	2(-)
190m1Tl		130(90)# keV			3.7(3) min	β+	190Hg	7(+#)
190m2Tl		290(70)# keV			750(40) µs			(8-)
190m3Tl		410(70)# keV			>1 µs			9-
191Tl		81	110	190.971786(8)	20# min	β+	191Hg	(1/2+)
191mTl		297(7) keV			5.22(16) min	β+	191Hg	9/2(-)
192Tl		81	111	191.97223(3)	9.6(4) min	β+	192Hg	(2-)
192m1Tl		160(50) keV			10.8(2) min	β+	192Hg	(7+)
192m2Tl		407(54) keV			296(5) ns			(8-)
193Tl		81	112	192.97067(12)	21.6(8) min	β+	193Hg	1/2(+#)
193mTl		369(4) keV			2.11(15) min	IT (75%)	193Tl	9/2-
						β+ (25%)	193Hg
194Tl		81	113	193.97120(15)	33.0(5) min	β+	194Hg	2-
						α (10−7%)	190Au
194mTl		300(200)# keV			32.8(2) min	β+	194Hg	(7+)
195Tl		81	114	194.969774(15)	1.16(5) h	β+	195Hg	1/2+
195mTl		482.63(17) keV			3.6(4) s	IT	195Tl	9/2-
196Tl		81	115	195.970481(13)	1.84(3) h	β+	196Hg	2-
196mTl		394.2(5) keV			1.41(2) h	β+ (95.5%)	196Hg	(7+)
						IT (4.5%)	196Tl
197Tl		81	116	196.969575(18)	2.84(4) h	β+	197Hg	1/2+
197mTl		608.22(8) keV			540(10) ms	IT	197Tl	9/2-
198Tl		81	117	197.97048(9)	5.3(5) h	β+	198Hg	2-
198m1Tl		543.5(4) keV			1.87(3) h	β+ (54%)	198Hg	7+
						IT (46%)	198Tl
198m2Tl		687.2(5) keV			150(40) ns			(5+)
198m3Tl		742.3(4) keV			32.1(10) ms			(10-)#
199Tl		81	118	198.96988(3)	7.42(8) h	β+	199Hg	1/2+
199mTl		749.7(3) keV			28.4(2) ms	IT	199Tl	9/2-
200Tl		81	119	199.970963(6)	26.1(1) h	β+	200Hg	2-
200m1Tl		753.6(2) keV			34.3(10) ms	IT	200Tl	7+
200m2Tl		762.0(2) keV			0.33(5) µs			5+
201TlMain isotope used in scintigraphy Scintigraphy Scintigraphy is a form of diagnostic test used in nuclear medicine, wherein radioisotopes are taken internally, and the emitted radiation is captured by external detectors to form two-dimensional images...		81	120	200.970819(16)	72.912(17) h	EC Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino...	201Hg	1/2+
201mTl		919.50(9) keV			2.035(7) ms	IT	201Tl	(9/2-)
202Tl		81	121	201.972106(16)	12.23(2) d	β+	202Hg	2-
202mTl		950.19(10) keV			572(7) µs			7+
203Tl		81	122	202.9723442(14)	Observationally StableBelieved to undergo α decay to 199Au			1/2+	0.2952(1)	0.29494-0.29528
203mTl		3400(300) keV			7.7(5) µs			(25/2+)
204Tl		81	123	203.9738635(13)	3.78(2) a	β- (97.1%)	204Pb	2-
						EC (2.9%)	204Hg
204m1Tl		1104.0(4) keV			63(2) µs			(7)+
204m2Tl		2500(500) keV			2.6(2) µs			(12-)
204m3Tl		3500(500) keV			1.6(2) µs			(20+)
205TlFinal decay product of 4n+1 decay chain Decay chain In nuclear science, the decay chain refers to the radioactive decay of different discrete radioactive decay products as a chained series of transformations...  (the Neptunium series)		81	124	204.9744275(14)	Observationally StableBelieved to undergo α decay to 201Au			1/2+	0.7048(1)	0.70472-0.70506
205m1Tl		3290.63(17) keV			2.6(2) µs			25/2+
205m2Tl		4835.6(15) keV			235(10) ns			(35/2-)
206Tl	Radium E	81	125	205.9761103(15)	4.200(17) min	β-	206Pb	0-	TraceIntermediate decay product Decay product In nuclear physics, a decay product is the remaining nuclide left over from radioactive decay. Radioactive decay often involves a sequence of steps...  of 238U Uranium-238 Uranium-238 is the most common isotope of uranium found in nature. It is not fissile, but is a fertile material: it can capture a slow neutron and after two beta decays become fissile plutonium-239...
206mTl		2643.11(19) keV			3.74(3) min	IT	206Tl	(12-)
207Tl	Actinium C	81	126	206.977419(6)	4.77(2) min	β-	207Pb	1/2+	TraceIntermediate decay product Decay product In nuclear physics, a decay product is the remaining nuclide left over from radioactive decay. Radioactive decay often involves a sequence of steps...  of 235U Uranium-235 - References :* .* DOE Fundamentals handbook: Nuclear Physics and Reactor theory , .* A piece of U-235 the size of a grain of rice can produce energy equal to that contained in three tons of coal or fourteen barrels of oil. -External links:* * * one of the earliest articles on U-235 for the...
207mTl		1348.1(3) keV			1.33(11) s	IT (99.9%)	207Tl	11/2-
						β- (.1%)	207Pb
208Tl	Thorium C	81	127	207.9820187(21)	3.053(4) min	β-	208Pb	5(+)	TraceIntermediate decay product Decay product In nuclear physics, a decay product is the remaining nuclide left over from radioactive decay. Radioactive decay often involves a sequence of steps...  of 232Th
209Tl		81	128	208.985359(8)	2.161(7) min	β-	209Pb	(1/2+)
210Tl	Radium C	81	129	209.990074(12)	1.30(3) min	β- (99.991%)	210Pb	(5+)#	Trace
						β-, n Neutron emission Neutron emission is a type of radioactive decay of atoms containing excess neutrons, in which a neutron is simply ejected from the nucleus. Two examples of isotopes which emit neutrons are helium-5 and beryllium-13... (.009%)	209Pb
211Tl		81	130	210.99348(22)#	1# min [>300 ns]			1/2+#
212Tl		81	131	211.99823(32)#	30# s [>300 ns]			5+#

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.