Neodymium
| Isotope | Atomic mass (Da) | Isotopic abundance (amount fraction) |
|---|---|---|
| 142Nd | 141.907 73(1) | 0.271 52(40) |
| 143Nd | 142.909 82(1) | 0.121 74(26) |
| 144Nd | 143.910 09(1) | 0.237 98(19) |
| 145Nd | 144.912 58(1) | 0.082 93(12) |
| 146Nd | 145.913 12(1) | 0.171 89(32) |
| 148Nd | 147.916 90(2) | 0.057 56(21) |
| 150Nd | 149.920 902(9) | 0.056 38(28) |
Two isotopes of neodymium,144Nd and145Nd, are radioactive but with half-lives so long (2.1(4)×1015a, and more than 6×1016 a, respectively) that there is no measurable effect on the atomic weight of Nd comparablewith the precision of the standard atomic weight.143Nd is the decay product of radioactive147Sm.
Although the resulting fluctuations ofn(143Nd)/n(144Nd) are also too small to affectAr(Nd), they are measurable and do permit deductions to be made in geochronology and in geochemicalphenomena, for instance, the mixing of ocean currents. For such applications, precisemeasurements of isotope abundances and Sm/Nd ratios are needed, and these are greatly facilitated bycomparisons with standard solutions. The "g" notation arises from the presence of naturally occurringfission products found in fossil reactors at Gabon, south-west Africa.
© IUPAC 2003
CIAAW
Neodymium
Ar(Nd) = 144.242(3) since 2005
The name derives from the Greekneos for "new" anddidymos for "twin". It was discovered by theSwedish surgeon and chemist Carl Gustav Mosander in 1841, who called it didymium (or twin) becauseof its similarity to lanthanum, which he had previously discovered two years earlier. In 1885, theAustrian chemist Carl Auer (Baron von Welsbach) separated didymium into two elements, one of which hecalled neodymium (or new twin).
