Neodymium [KNEE-OH-DIM-EE-UM] is present in misch metal (an
alloy of rare earth elements in various naturally occurring proportions) 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.
•Name: Neodymium
•Symbol: Nd
•Atomic number: 60
•Atomic weight: 144.242 (3) [see note g]
•Standard state: solid at 298 K
•CAS Registry ID: 7440-00-8
•Group in periodic table:
•Group name: Lanthanoid
•Period in periodic table: 6 (lanthanoid)
•Block in periodic table: f-block
•Color: silvery white, yellowish tinge
•Classification: Metallic
Historical information
Neodymium was discovered by Carl F. Auer von Welsbach at 1885 in Austria. Von Welsbach separated didymium, an extract of cerite, into two new elemental components, neodymia and praseodymia, by repeated fractionation of ammonium didymium nitrate. Origin of name: from the Greek words "neos didymos" meaning "new twin". While the free metal is a component of misch metal, (a pyrophoric alloy for lighter flints), the element was not isolated in relatively pure form until 1925.
Physical properties
•Melting point: 1297 [or 1024 °C (1875 °F)] K
•Boiling point: 3373 [or 3100 °C (5612 °F)] K
•Density of solid: 6800 kg m-3
Orbital properties
•Ground state electron configuration: [Xe].4f4.6s2
•Shell structure: 2.8.18.22.8.2
•Term symbol: 5I4
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.
•Name: Neodymium
•Symbol: Nd
•Atomic number: 60
•Atomic weight: 144.242 (3) [see note g]
•Standard state: solid at 298 K
•CAS Registry ID: 7440-00-8
•Group in periodic table:
•Group name: Lanthanoid
•Period in periodic table: 6 (lanthanoid)
•Block in periodic table: f-block
•Color: silvery white, yellowish tinge
•Classification: Metallic
Historical information
Neodymium was discovered by Carl F. Auer von Welsbach at 1885 in Austria. Von Welsbach separated didymium, an extract of cerite, into two new elemental components, neodymia and praseodymia, by repeated fractionation of ammonium didymium nitrate. Origin of name: from the Greek words "neos didymos" meaning "new twin". While the free metal is a component of misch metal, (a pyrophoric alloy for lighter flints), the element was not isolated in relatively pure form until 1925.
Physical properties
•Melting point: 1297 [or 1024 °C (1875 °F)] K
•Boiling point: 3373 [or 3100 °C (5612 °F)] K
•Density of solid: 6800 kg m-3
Orbital properties
•Ground state electron configuration: [Xe].4f4.6s2
•Shell structure: 2.8.18.22.8.2
•Term symbol: 5I4
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.
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