Isotopes of lanthanum

Naturally occurring lanthanum (57La) is composed of one stable (139La) and one radioactive (138La) isotope, with the stable isotope, 139La, being the most abundant (99.91% natural abundance). There are 38 radioisotopes that have been characterized, with the most stable being 138La, with a half-life of 1.02×1011 years; 137La, with a half-life of 60,000 years and 140La, with a half-life of 1.6781 days. The remaining radioactive isotopes have half-lives that are less than a day and the majority of these have half-lives that are less than 1 minute. This element also has 12 nuclear isomers, the longest-lived of which is 132mLa, with a half-life of 24.3 minutes.

The isotopes of lanthanum range in atomic weight from 116.95 u (117La) to 154.96 u (155La).

Main isotopes of lanthanum (57La)
Iso­tope Decay
abun­dance half-life (t1/2) mode pro­duct
137La syn 6×104 y ε 137Ba
138La 0.089% 1.05×1011 y ε 138Ba
β 138Ce
139La 99.911% stable
Standard atomic weight Ar, standard(La)
  • 138.90547(7)[1]
Lanthanum stable nucleus
Stable Z/N chart of La and Ba

List of isotopes

nuclide
symbol
Z(p) N(n)  
isotopic mass (u)
 
half-life[n 1] decay
mode(s)[2][n 2]
daughter
isotope(s)[n 3]
nuclear
spin and
parity
representative
isotopic
composition
(mole fraction)
range of natural
variation
(mole fraction)
excitation energy
117La 57 60 116.95007(43)# 23.5(26) ms β+ 117Ba (3/2+,3/2−)
p 116Ba
117mLa 151(12) keV 10(5) ms (9/2+)
118La 57 61 117.94673(32)# 200# ms β+ 118Ba
119La 57 62 118.94099(43)# 1# s β+ 119Ba 11/2−#
120La 57 63 119.93807(54)# 2.8(2) s β+ 120Ba
β+, p 119Cs
121La 57 64 120.93301(54)# 5.3(2) s β+ 121Ba 11/2−#
β+, p 120Cs
122La 57 65 121.93071(32)# 8.6(5) s β+ 122Ba
β+, p 121Cs
123La 57 66 122.92624(21)# 17(3) s β+ 123Ba 11/2−#
124La 57 67 123.92457(6) 29.21(17) s β+ 124Ba (7−,8−)
124mLa 100(100)# keV 21(4) s low(+#)
125La 57 68 124.920816(28) 64.8(12) s β+ 125Ba (11/2−)
125mLa 107.0(10) keV 390(40) ms (3/2+)
126La 57 69 125.91951(10) 54(2) s β+ 126Ba (5)(+#)
126mLa 210(410) keV 20(20) s (0−,1−,2−)
127La 57 70 126.916375(28) 5.1(1) min β+ 127Ba (11/2−)
127mLa 14.8(12) keV 3.7(4) min β+ 127Ba (3/2+)
IT 127La
128La 57 71 127.91559(6) 5.18(14) min β+ 128Ba (5+)
128mLa 100(100)# keV <1.4 min IT 128La (1+,2−)
129La 57 72 128.912693(22) 11.6(2) min β+ 129Ba 3/2+
129mLa 172.1(4) keV 560(50) ms IT 129La 11/2−
130La 57 73 129.912369(28) 8.7(1) min β+ 130Ba 3(+)
131La 57 74 130.91007(3) 59(2) min β+ 131Ba 3/2+
131mLa 304.52(24) keV 170(10) µs 11/2−
132La 57 75 131.91010(4) 4.8(2) h β+ 132Ba 2−
132mLa 188.18(11) keV 24.3(5) min IT (76%) 132La 6−
β+ (24%) 132Ba
133La 57 76 132.90822(3) 3.912(8) h β+ 133Ba 5/2+
134La 57 77 133.908514(21) 6.45(16) min β+ 134Ba 1+
135La 57 78 134.906977(11) 19.5(2) h β+ 135Ba 5/2+
136La 57 79 135.90764(6) 9.87(3) min β+ 136Ba 1+
136mLa 255(9) keV 114(3) ms IT 136La (8)(−#)
137La 57 80 136.906494(14) 6(2)×104 y EC 137Ba 7/2+
138La[n 4] 57 81 137.907112(4) 1.02(1)×1011 y β+ (66.4%) 138Ba 5+ 9.0(1)×10−4
β (33.6%) 138Ce
138mLa 72.57(3) keV 116(5) ns (3)+
139La[n 5] 57 82 138.9063533(26) Stable 7/2+ 0.99910(1)
140La[n 5] 57 83 139.9094776(26) 1.6781(3) d β 140Ce 3−
141La 57 84 140.910962(5) 3.92(3) h β 141Ce (7/2+)
142La 57 85 141.914079(6) 91.1(5) min β 142Ce 2−
143La 57 86 142.916063(17) 14.2(1) min β 143Ce (7/2)+
144La 57 87 143.91960(5) 40.8(4) s β 144Ce (3−)
145La 57 88 144.92165(10) 24.8(20) s β 145Ce (5/2+)
146La 57 89 145.92579(8) 6.27(10) s β (99.99%) 146Ce 2−
β, n (.007%) 145Ce
146mLa 130(130) keV 10.0(1) s β 146Ce (6−)
147La 57 90 146.92824(5) 4.015(8) s β (99.96%) 147Ce (5/2+)
β, n (.04%) 146Ce
148La 57 91 147.93223(6) 1.26(8) s β (99.85%) 148Ce (2−)
β, n (.15%) 147Ce
149La 57 92 148.93473(34)# 1.05(3) s β (98.6%) 149Ce 5/2+#
β, n (1.4%) 148Ce
150La 57 93 149.93877(43)# 510(30) ms β (97.3%) 150Ce (3+)
β, n (2.7%) 149Ce
151La 57 94 150.94172(43)# 300# ms [>300 ns] β 151Ce 5/2+#
152La 57 95 151.94625(43)# 200# ms [>300 ns] β 152Ce
153La 57 96 152.94962(64)# 150# ms [>300 ns] β 153Ce 5/2+#
154La 57 97 153.95450(64)# 100# ms β 154Ce
155La 57 98 154.95835(86)# 60# ms β 155Ce 5/2+#
  1. ^ Bold for isotopes with half-lives longer than the age of the universe (nearly stable)
  2. ^ Abbreviations:
    EC: Electron capture
    IT: Isomeric transition
  3. ^ Bold for stable isotopes, bold italics for near-stable isotopes (half-life longer than the age of the universe)
  4. ^ Primordial radionuclide
  5. ^ a b Fission product

Notes

  • Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.
  • 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

  1. ^ Meija, Juris; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305.
  2. ^ "Universal Nuclide Chart". nucleonica.
Cerium

Cerium is a chemical element with the symbol Ce and atomic number 58. Cerium is a soft, ductile and silvery-white metal that tarnishes when exposed to air, and it is soft enough to be cut with a knife. Cerium is the second element in the lanthanide series, and while it often shows the +3 oxidation state characteristic of the series, it also exceptionally has a stable +4 state that does not oxidize water. It is also considered one of the rare-earth elements. Cerium has no biological role and is not very toxic.

Despite always occurring in combination with the other rare-earth elements in minerals such as those of the monazite and bastnäsite groups, cerium is easy to extract from its ores, as it can be distinguished among the lanthanides by its unique ability to be oxidized to the +4 state. It is the most common of the lanthanides, followed by neodymium, lanthanum, and praseodymium. It is the 26th-most abundant element, making up 66 ppm of the Earth's crust, half as much as chlorine and five times as much as lead.

Cerium was the first of the lanthanides to be discovered, in Bastnäs, Sweden by Jöns Jakob Berzelius and Wilhelm Hisinger in 1803, and independently by Martin Heinrich Klaproth in Germany in the same year. In 1839 Carl Gustaf Mosander became the first to isolate the metal. Today, cerium and its compounds have a variety of uses: for example, cerium(IV) oxide is used to polish glass and is an important part of catalytic converters. Cerium metal is used in ferrocerium lighters for its pyrophoric properties. Cerium-doped YAG phosphor is used in conjunction with blue light-emitting diodes to produce white light in most commercial white LED light sources.

Lanthanum

Lanthanum is a chemical element with the symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes rapidly when exposed to air and is soft enough to be cut with a knife. It is the eponym of the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table, of which lanthanum is the first and the prototype. It is also sometimes considered the first element of the 6th-period transition metals, which would put it in group 3, although lutetium is sometimes placed in this position instead. Lanthanum is traditionally counted among the rare earth elements. The usual oxidation state is +3. Lanthanum has no biological role in humans but is essential to some bacteria. It is not particularly toxic to humans but does show some antimicrobial activity.

Lanthanum usually occurs together with cerium and the other rare earth elements. Lanthanum was first found by the Swedish chemist Carl Gustav Mosander in 1839 as an impurity in cerium nitrate – hence the name lanthanum, from the Ancient Greek λανθάνειν (lanthanein), meaning "to lie hidden". Although it is classified as a rare earth element, lanthanum is the 28th most abundant element in the Earth's crust, almost three times as abundant as lead. In minerals such as monazite and bastnäsite, lanthanum composes about a quarter of the lanthanide content. It is extracted from those minerals by a process of such complexity that pure lanthanum metal was not isolated until 1923.

Lanthanum compounds have numerous applications as catalysts, additives in glass, carbon arc lamps for studio lights and projectors, ignition elements in lighters and torches, electron cathodes, scintillators, GTAW electrodes, and other things. Lanthanum carbonate is used as a phosphate binder in cases of renal failure.

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