Neodymium: the essentials
Neodymium atoms have 60 electrons and the shell structure is 22.214.171.124.8.2. The ground state electronic configuration of neutral neodymium is [Xe].4f4.6s2 and the term symbol of neodymium is 5I4.
Neodymium is present in misch metal to the extent of about 18%. The metal has a bright silvery metallic lustre. Neodymium is one of the more reactive rare-earth metals and quickly tarnishes in air, forming an oxide that spalls off and exposes the metal to further oxidation. It is one of the rare earth metals.
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Neodymium: physical properties
Neodymium: heat properties
- Melting point: 1297 [1024 °C (1875 °F)] K
- Boiling point: 1297 [1024 °C (1875 °F)] K
- Enthalpy of fusion: 20.5 kJ mol-1
Neodymium: atom sizes
- Atomic radius (empirical): 185 pm
- Molecular single bond covalent radius: 174 (coordination number 3,6) ppm
- van der Waals radius: 295 ppm
- Pauling electronegativity: 1.14 (Pauling units)
- Allred Rochow electronegativity: 1.07 (Pauling units)
- Mulliken-Jaffe electronegativity: (no data)
Neodymium: orbital properties
- First ionisation energy: 533.08 kJ mol‑1
- Second ionisation energy: 1040.4 kJ mol‑1
- Third ionisation energy: 2130 kJ mol‑1
Neodymium: crystal structure
Neodymium: biological data
- Human abundance by weight: (no data) ppb by weight
Neodymium has no biological role.
Reactions of neodymium as the element with air, water, halogens, acids, and bases where known.
Neodymium: binary compounds
Binary compounds with halogens (known as halides), oxygen (known as oxides), hydrogen (known as hydrides), and other compounds of neodymium where known.
Neodymium: compound properties
Bond strengths; lattice energies of neodymium halides, hydrides, oxides (where known); and reduction potentials where known.
Neodymium: historyNeodymium was discovered by Carl F. Auer von Welsbach in 1885 at Austria. Origin of name: from the Greek words "neos didymos" meaning "new twin".
Neodymium isotopes are used in a variety of scientific applications. Nd-142 has been used for the production of short-lived Tm and Yb isotopes. Nd-146 has been suggested for the production of Pm-147 which can be used as a source for radioisotopic power generation. Several Nd isotopes have been used for the production of other Pm isotopes. Finally, Nd-150 has been used to study double beta decay.
Isolation: neodymium metal is available commercially so it is not normally necessary to make it in the laboratory, which is just as well as it is difficult to isolate as the pure metal. This is largely because of the way it is found in nature. The lanthanoids are found in nature in a number of minerals. The most important are xenotime, monazite, and bastnaesite. The first two are orthophosphate minerals LnPO4 (Ln deonotes a mixture of all the lanthanoids except promethium which is vanishingly rare) and the third is a fluoride carbonate LnCO3F. Lanthanoids with even atomic numbers are more common. The most comon lanthanoids in these minerals are, in order, cerium, lanthanum, neodymium, and praseodymium. Monazite also contains thorium and ytrrium which makes handling difficult since thorium and its decomposition products are radioactive.
For many purposes it is not particularly necessary to separate the metals, but if separation into individual metals is required, the process is complex. Initially, the metals are extracted as salts from the ores by extraction with sulphuric acid (H2SO4), hydrochloric acid (HCl), and sodium hydroxide (NaOH). Modern purification techniques for these lanthanoid salt mixtures are ingenious and involve selective complexation techniques, solvent extractions, and ion exchange chromatography.
Pure neodymium is available through the reduction of NdF3 with calcium metal.
2NdF3 + 3Ca → 2Nd + 3CaF2
This would work for the other calcium halides as well but the product CaF2 is easier to handle under the reaction conditions (heat to 50°C above the melting point of the element in an argon atmosphere). Excess calcium is removed from the reaction mixture under vacuum.