View source for Isotopes of technetium



'''[[Technetium]]''' ('''Tc''') is one of the two elements in the first 82 that have no stable [[isotope]]s (in fact, it is the lowest-numbered element that is exclusively radioactive); the other such element is [[promethium]].<ref>''LANL Periodic Table'', "Technetium" paragraph 2</ref> The most stable [[Radionuclide|radioisotope]]s are <sup>98</sup>Tc ([[half-life]] of 4.2 [[Annum|Ma]]), <sup>97</sup>Tc (half-life: 2.6 Ma) and <sup>99</sup>Tc (half-life: 211.1 [[annum|ka]]).<ref name="environmentalchemistry">  EnvironmentalChemistry.com, "Technetium",  Nuclides / Isotopes</ref>

Twenty-two other radioisotopes have been characterized with [[atomic mass]]es ranging from 87.933 [[atomic mass unit|u]] (<sup>88</sup>Tc) to 112.931 u (<sup>113</sup>Tc). Most of these have half-lives that are less than an hour; the exceptions are <sup>93</sup>Tc (half-life: 2.75 hours), <sup>94</sup>Tc (half-life: 4.883 hours), <sup>95</sup>Tc (half-life: 20 hours), and <sup>96</sup>Tc (half-life: 4.28 days).<ref name="environmentalchemistry"/>

Technetium also has numerous [[nuclear isomer|meta states]].  <sup>97m</sup>Tc is the most stable, with a half-life of 90.1 days (0.097 MeV). This is followed by <sup>95m</sup>Tc (half life: 61 days, 0.038 MeV), and <sup>99m</sup>Tc (half-life: 6.01 hours, 0.143 MeV). <sup>99m</sup>Tc only emits [[gamma ray]]s, subsequently decaying to <sup>99</sup>Tc.<ref name="environmentalchemistry"/>

For isotopes lighter than the most stable isotope, <sup>98</sup>Tc, the primary [[decay mode]] is [[electron capture]], giving [[molybdenum]]. For the heavier isotopes, the primary mode is [[Beta decay|beta emission]], giving [[ruthenium]], with the exception that <sup>100</sup>Tc can decay both by beta emission and electron capture.<ref name="environmentalchemistry"/><ref>CRC Handbook, 85th edition, table of the isotopes</ref>

Technetium-99 is the most common and most readily available isotope, as it is a major product of the fission of uranium-235.  One gram of <sup>99</sup>Tc produces 6.2×10<sup>8</sup> disintegrations a second (that is, 0.62 G[[Becquerel|Bq]]/g).<ref>''The Encyclopedia of the Chemical Elements'', page 693, "Toxicology", paragraph 2</ref>

=== Stability of technetium isotopes ===
Technetium and [[promethium]] are unusual light elements in that they have no stable isotopes. The reason for this is somewhat complicated. 

Using the [[liquid drop model]] for atomic nuclei, one can derive a semiempirical formula for the binding energy of a nucleus. This formula predicts a "valley of beta stability" along which nuclides do not undergo beta decay.  Nuclides that lie "up the walls" of the valley tend to decay by beta decay towards the center (by emitting an electron, emitting a [[positron]], or capturing an electron).  For a fixed number of nucleons ''A'', the binding energies lie on one or more [[parabola]]s, with the most stable nuclide at the bottom.  One can have more than one parabola because isotopes with an even number of protons and an even number of neutrons are more stable than isotopes with an odd number of neutrons and an odd number of protons. A single beta decay then transforms one into the other.  When there is only one parabola, there can be only one stable isotope lying on that parabola.  When there are two parabolas, that is, when the number of nucleons is even, it can happen (rarely) that there is a stable nucleus with an odd number of neutrons and an odd number of protons (although this happens only in four instances).  However, if this happens, there can be no stable isotope with an even number of neutrons and an even number of protons. 

For technetium (''Z''=43), the valley of beta stability is centered at around 98 nucleons.  However, for every number of nucleons from 95 to 102, there is already at least one stable nuclide of either molybdenum (''Z''=42) or ruthenium (''Z''=44).  For the isotopes with odd numbers of nucleons, this immediately rules out a stable isotope of technetium, since there can be only one stable nuclide with a fixed odd number of nucleons.  For the isotopes with an even number of nucleons, since technetium has an odd number of protons, any isotope must also have an odd number of neutrons.  In such a case, the presence of a stable nuclide having the same number of nucleons and an even number of protons rules out the possibility of a stable nucleus.<ref>RADIOCHEMISTRY and NUCLEAR CHEMISTRY</ref>

== Table ==
{| class="wikitable" style="font-size:95%; white-space:nowrap"
! rowspan="2" | nuclide<br />symbol
! Z([[proton|p]])
! N([[neutron|n]])
! &nbsp;<br />isotopic mass (u)<br />&nbsp;
! rowspan="2" | half-life
! rowspan="2" | nuclear<br />spin
! rowspan="2" | representative<br />isotopic<br />composition<br />(mole fraction)
! rowspan="2" | range of natural<br />variation<br />(mole fraction)
|-
! colspan="3" | excitation energy
|-
| <sup>85</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 42
| 84.94883(43)#
| <110 ns
| 1/2-#
|
|
|-
| <sup>86</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 43
| 85.94288(32)#
| 55(6) ms
| (0+)
|
|
|-
| style="text-indent:1em" | <sup>86m</sup>Tc
| colspan="3" style="text-indent:2em" | 1500(150) keV
| 1.11(21) µs
| (5+,5-)
|
|
|-
| <sup>87</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 44
| 86.93653(32)#
| 2.18(16) s
| 1/2-#
|
|
|-
| style="text-indent:1em" | <sup>87m</sup>Tc
| colspan="3" style="text-indent:2em" | 20(60)# keV
| 2# s
| 9/2+#
|
|
|-
| <sup>88</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 45
| 87.93268(22)#
| 5.8(2) s
| (2,3)
|
|
|-
| style="text-indent:1em" | <sup>88m</sup>Tc
| colspan="3" style="text-indent:2em" | 0(300)# keV
| 6.4(8) s
| (6,7,8)
|
|
|-
| <sup>89</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 46
| 88.92717(22)#
| 12.8(9) s
| (9/2+)
|
|
|-
| style="text-indent:1em" | <sup>89m</sup>Tc
| colspan="3" style="text-indent:2em" | 62.6(5) keV
| 12.9(8) s
| (1/2-)
|
|
|-
| <sup>90</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 47
| 89.92356(26)
| 8.7(2) s
| 1+
|
|
|-
| style="text-indent:1em" | <sup>90m</sup>Tc
| colspan="3" style="text-indent:2em" | 310(390) keV
| 49.2(4) s
| (8+)
|
|
|-
| <sup>91</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 48
| 90.91843(22)
| 3.14(2) min
| (9/2)+
|
|
|-
| style="text-indent:1em" | <sup>91m</sup>Tc
| colspan="3" style="text-indent:2em" | 139.3(3) keV
| 3.3(1) min
| (1/2)-
|
|
|-
| <sup>92</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 49
| 91.915260(28)
| 4.25(15) min
| (8)+
|
|
|-
| style="text-indent:1em" | <sup>92m</sup>Tc
| colspan="3" style="text-indent:2em" | 270.15(11) keV
| 1.03(7) µs
| (4+)
|
|
|-
| <sup>93</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 50
| 92.910249(4)
| 2.75(5) h
| 9/2+
|
|
|-
| style="text-indent:1em" | <sup>93m1</sup>Tc
| colspan="3" style="text-indent:2em" | 391.84(8) keV
| 43.5(10) min
| 1/2-
|
|
|-
| style="text-indent:1em" | <sup>93m2</sup>Tc
| colspan="3" style="text-indent:2em" | 2185.16(15) keV
| 10.2(3) µs
| (17/2)-
|
|
|-
| <sup>94</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 51
| 93.909657(5)
| 293(1) min
| 7+
|
|
|-
| style="text-indent:1em" | <sup>94m</sup>Tc
| colspan="3" style="text-indent:2em" | 75.5(19) keV
| 52.0(10) min
| (2)+
|
|
|-
| <sup>95</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 52
| 94.907657(6)
| 20.0(1) h
| 9/2+
|
|
|-
| style="text-indent:1em" | <sup>95m</sup>Tc
| colspan="3" style="text-indent:2em" | 38.89(5) keV
| 61(2) d
| 1/2-
|
|
|-
| <sup>96</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 53
| 95.907871(6)
| 4.28(7) d
| 7+
|
|
|-
| style="text-indent:1em" | <sup>96m</sup>Tc
| colspan="3" style="text-indent:2em" | 34.28(7) keV
| 51.5(10) min
| 4+
|
|
|-
| <sup>97</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 54
| 96.906365(5)
| 2.6E+6 a
| 9/2+
|
|
|-
| style="text-indent:1em" | <sup>97m</sup>Tc
| colspan="3" style="text-indent:2em" | 96.56(6) keV
| 91.4(8) d
| 1/2-
|
|
|-
| <sup>98</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 55
| 97.907216(4)
| 4.2(3)E+6 a
| (6)+
|
|
|-
| style="text-indent:1em" | <sup>98m</sup>Tc
| colspan="3" style="text-indent:2em" | 90.76(16) keV
| 14.7(3) µs
| (2)-
|
|
|-
| [[Tc-99|<sup>99</sup>Tc]]
| style="text-align:right" | 43
| style="text-align:right" | 56
| 98.9062547(21)
| 2.111(12)E+5 a
| 9/2+
|
|
|-
| style="text-indent:1em" | [[Tc-99m|<sup>99m</sup>Tc]]
| colspan="3" style="text-indent:2em" | 142.6832(11) keV
| 6.0058(12) h
| 1/2-
|
|
|-
| <sup>100</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 57
| 99.9076578(24)
| 15.8(1) s
| 1+
|
|
|-
| style="text-indent:1em" | <sup>100m1</sup>Tc
| colspan="3" style="text-indent:2em" | 200.67(4) keV
| 8.32(14) µs
| (4)+
|
|
|-
| style="text-indent:1em" | <sup>100m2</sup>Tc
| colspan="3" style="text-indent:2em" | 243.96(4) keV
| 3.2(2) µs
| (6)+
|
|
|-
| <sup>101</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 58
| 100.907315(26)
| 14.22(1) min
| 9/2+
|
|
|-
| style="text-indent:1em" | <sup>101m</sup>Tc
| colspan="3" style="text-indent:2em" | 207.53(4) keV
| 636(8) µs
| 1/2-
|
|
|-
| <sup>102</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 59
| 101.909215(10)
| 5.28(15) s
| 1+
|
|
|-
| style="text-indent:1em" | <sup>102m</sup>Tc
| colspan="3" style="text-indent:2em" | 20(10) keV
| 4.35(7) min
| (4,5)
|
|
|-
| <sup>103</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 60
| 102.909181(11)
| 54.2(8) s
| 5/2+
|
|
|-
| <sup>104</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 61
| 103.91145(5)
| 18.3(3) min
| (3+)#
|
|
|-
| style="text-indent:1em" | <sup>104m1</sup>Tc
| colspan="3" style="text-indent:2em" | 69.7(2) keV
| 3.5(3) µs
| 2(+)
|
|
|-
| style="text-indent:1em" | <sup>104m2</sup>Tc
| colspan="3" style="text-indent:2em" | 106.1(3) keV
| 0.40(2) µs
| (+)
|
|
|-
| <sup>105</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 62
| 104.91166(6)
| 7.6(1) min
| (3/2-)
|
|
|-
| <sup>106</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 63
| 105.914358(14)
| 35.6(6) s
| (1,2)
|
|
|-
| <sup>107</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 64
| 106.91508(16)
| 21.2(2) s
| (3/2-)
|
|
|-
| style="text-indent:1em" | <sup>107m</sup>Tc
| colspan="3" style="text-indent:2em" | 65.7(10) keV
| 184(3) ns
| (5/2-)
|
|
|-
| <sup>108</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 65
| 107.91846(14)
| 5.17(7) s
| (2)+
|
|
|-
| <sup>109</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 66
| 108.91998(10)
| 860(40) ms
| 3/2-#
|
|
|-
| <sup>110</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 67
| 109.92382(8)
| 0.92(3) s
| (2+)
|
|
|-
| <sup>111</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 68
| 110.92569(12)
| 290(20) ms
| 3/2-#
|
|
|-
| <sup>112</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 69
| 111.92915(13)
| 290(20) ms
| 2+#
|
|
|-
| <sup>113</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 70
| 112.93159(32)#
| 170(20) ms
| 3/2-#
|
|
|-
| <sup>114</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 71
| 113.93588(64)#
| 150(30) ms
| 2+#
|
|
|-
| <sup>115</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 72
| 114.93869(75)#
| 100# ms [>300 ns]
| 3/2-#
|
|
|-
| <sup>116</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 73
| 115.94337(75)#
| 90# ms [>300 ns]
| 2+#
|
|
|-
| <sup>117</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 74
| 116.94648(75)#
| 40# ms [>300 ns]
| 3/2-#
|
|
|-
| <sup>118</sup>Tc
| style="text-align:right" | 43
| style="text-align:right" | 75
| 117.95148(97)#
| 30# ms [>300 ns]
| 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==
{{Reflist}}
* Isotope masses from [http://www.nndc.bnl.gov/amdc/index.html 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 [http://www.iupac.org/publications/pac/2003/7506/7506x0683.html Atomic weights of the elements. Review 2000 (IUPAC Technical Report)]. ''Pure Appl. Chem.'' Vol. 75, No. 6, pp. 683-800, (2003) and [http://www.iupac.org/news/archives/2005/atomic-weights_revised05.html 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. [http://amdc.in2p3.fr/web/nubase_en.html 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 [http://www.nndc.bnl.gov/nudat2/ 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.

{{Isotope nav | element=technetium | lighter=Isotopes of molybdenum | heavier=Isotopes of ruthenium }}

[[Category:Isotopes|Technetium]]
[[Category:Technetium]]
[[Category:Fission products|Technetium-99]]

[[zh:鎝的同位素]]
opes of technetium]]

{{WikiDoc Help Menu}}
{{WS}}