Science Fair Project Encyclopedia
|Name, Symbol, Number||Neodymium, Nd, 60|
|Group, Period, Block||_ , 6, f|
|Density, Hardness||6800 kg/m3, no data|
|Appearance||silvery white, yellowish tinge|
|Atomic weight||144.24(3) amu|
|Atomic radius (calc.)||185 (206) pm|
|Covalent radius||no data|
|van der Waals radius||no data|
|e- 's per energy level||2, 8, 18, 22, 8, 2|
|Oxidation states (Oxide)||3 (mildly basic)|
|State of matter||solid (__)|
|Melting point||1297 K (1875 °F)|
|Boiling point||3373 K (5612 °F)|
|Molar volume||20.59 ×10-6 m3/mol|
|Heat of vaporization||273 kJ/mol|
|Heat of fusion||7.14 kJ/mol|
|Vapor pressure||6.03E-3 Pa at 2890 K|
|Velocity of sound||2330 m/s at 293.15 K|
|Electronegativity||1.14 (Pauling scale)|
|Specific heat capacity||190 J/(kg*K)|
|Electrical conductivity||1.57 106/m ohm|
|Thermal conductivity||16.5 W/(m*K)|
|1st ionization potential||533.1 kJ/mol|
|2nd ionization potential||1040 kJ/mol|
|3rd ionization potential||2130 kJ/mol|
|4th ionization potential||3900 kJ/mol|
|Most stable isotopes|
|SI units & STP are used except where noted.|
Neodymium, a rare earth metal, is present in misch metal to the extent of about 18%. The metal has a bright silvery metallic luster; however, being one of the more reactive rare-earth metals, neodymium quickly tarnishes in air, forming an oxide that spalls off and exposes the metal to further oxidation.
Uses of neodymium include:
- Neodymium is a component of didymium used for colouring glass to make welder's goggles.
- Neodymium colours glass in delicate shades ranging from pure violet through wine-red and warm gray. Light transmitted through such glass shows unusually sharp absorption bands; the glass is used in astronomical work to produce sharp bands by which spectral lines may be calibrated. Neodymium is also used to remove the green colour caused by iron contaminants from glass.
- Certain transparent materials with a small concentration of neodymium ions can be used in lasers for infrared wavelengths (1054-1064 nm), e.g. Nd:YAG (yttrium aluminium garnet), Nd:YLF (yttrium lithium fluoride), Nd:YVO (yttrium vanadate), Nd:glass.
- Neodymium salts are used as a colourant for enamels.
- Neodymium is used in very powerful permanent magnets - Nd2Fe14B. These magnets are cheaper than Samarium-Cobalt magnets and appear in products such as Sennheiser or iPod in-ear headphones.
- Neodymium ions are used in active laser media.
- Probably because of similarities to Ca2+, Nd3+ has been reported  to promote plant growth. Rare earth element compounds are frequently used in China as fertilizer.
Neodymium was discovered by Baron Carl Auer von Welsbach, an Austrian chemist, in Vienna in 1885. He separated neodymium, as well as the element praseodymium, from a material known as didymium by means of spectroscopic analysis; however, it was not isolated in relatively pure form until 1925. The name neodymium is derived from the Greek words neos, new, and didymos, twin.
Neodymium is never found in nature as the free element; rather, it occurs in ores such as monazite sand ((Ce,La,Th,Nd,Y)PO4) and bastnasite ((Ce,La,Th,Nd,Y)(CO3)F) that contain small amounts of all the rare earth metals. Neodymium can also be found in Misch metal; it is difficult to separate from other rare earth elements.
Neodymium compounds include:
Naturally occurring Neodymium is composed of 5 stable isotopes, 142Nd, 143Nd, 145Nd, 146Nd and 148Nd, with 142Nd being the most abundant (27.2% natural abundance), and 2 radioisotopes, 144Nd and 150Nd. In all, 31 radioisotopes of Neodymium have been characterized, with the most stable being 150Nd with a half-life (T½) of >1.1×1019 years, 144Nd with a half-life of 2.29×1015 years, and 147Nd with a half-life of 10.98 days. All of the remaining radioactive isotopes have half-lives that are less than 3.38 days, and the majority of these have half-lives that are less than 71 seconds. This element also has 4 meta states with the most stable being 139Ndm (T½ 5.5 hours), 135Ndm (T½ 5.5 minutes) and 141Ndm (T½ 62.0 seconds).
The primary decay mode before the most abundant stable isotope, 142Nd, is electron capture and the primary mode after is beta minus decay. The primary decay products before 142Nd are element Pr (praseodymium) isotopes and the primary products after are element Pm (promethium) isotopes.
Neodymium metal dust is a combustion and explosion hazard.
Neodymium compounds, like all rare earth metals, are of low to moderate toxicity; however its toxicity has not been thoroughly investigated. Neodymium dust and salts are very irritating to the eyes and mucous membranes, and moderately irritating to skin. Breathing the dust can cause lung embolisms, and accumulated exposure damages the liver. Neodymium also acts as an anticoagulant, especially when given intravenously.
Neodymium magnets have been tested for medical uses such as magnetic braces and bone repair, but biocompatibility issues have prevented widespread application.
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