60
  Nd  
144.240000
Neodymium

Name: Neodymium
Symbol: Nd
Atomic Number: 60
Atomic Weight: 144.240000
Family: Rare Earth Elements
CAS RN: 7440-00-8
Description: A silvery white rare earth metal the oxidizes easily in air.
State (25C): Solid
Oxidation states: +3

Molar Volume: 20.6 cm3/mole
Valence Electrons: 4f46s2

Boiling Point: 3341K, 3068C, 5554F
Melting Point:1289K, 1016C, 1861F

Electrons Energy Level: 2,8,18,22,8,2
Isotopes: 33 + 5 Stable + 5 meta states
Heat of Vaporization: 273 kJ/mol
Heat of Fusion: 7.14 kJ/mol
Density: 7.01g/cm3 @ 300K
Specific Heat: 0.19 J/gK
Atomic Radius: 2.64
Ionic Radius: 0.995
Electronegativity: 1.14 (Pauling); 1.07 (Allrod Rochow)
57
La
138.9
58
Ce
140.1
59
Pr
140.9
60
Nd
144.2
61
Pm
(145)
62
Sm
150.4
63
Eu
152.0
64
Gd
157.3
65
Tb
158.9
66
Dy
162.5
67
Ho
164.9
68
Er
167.3
69
Tm
168.9
70
Yb
173.0
71
Lu
175.0

1s2 2s2p6 3s2p6d10 4s2p6d10f4 5s2p6 6s2

History

Neodymium, Greek neos + didymos (new twin).   In 1841, Mosander, extracted from cerite a new rose-colored oxide, which he believed contained a new element.  He named the element didymium, as it was an inseparable twin brother of lanthanum.  In 1885 Baron Carl Auer von Welsbach, an Austrian chemist,  separated didymium into two new elemental components, neodymia and praseodymia, by repeated fractionation of ammonium didymium nitrate by means of spectroscopic analysis..  While the free metal is in misch metal, long known and used as a pyrophoric alloy for light flints, the element was not isolated in relatively pure form until 1925. 

Neodymium is frequently misspelled as neodynium.  Today, neodymium is primarily obtained through an ion exchange process of monazite sand (Ce,La,Th,Nd,Y)PO4, a material rich in rare earth elements, and through electrolysis of its halide salts.

Characteristics

The silvery-white metal oxidizes easily in air and reacts with water, displacing hydrogen gas.  Although another of the "rare" earth metals, neodymium is actually more abundant than many better known metals such as gold, silver, tin and lead.  Neodymium quickly tarnishes in air.  The tarnishing forms an oxide layer that falls off, which exposes the metal to further oxidation.  Although a "rare earth metals," it constitutes 38 ppm of Earth's crust.

1s2
2s2 2p6
3s2 3p6 3d10
4s2 4p6 4d10 4f4
5s2 5p6
6s2

It is present in the minerals monazite and bastnasite, which are principal sources of rare-earth metals.  The element may be obtained by separating neodymium salts from other rare earths by ion-exchange or solvent extraction techniques, and by reducing anhydrous halides such as NdF3 with calcium metal.  Other separation techniques are possible.  Neodymium exists in two allotropic forms, with a transformation from a double hexagonal to a body-centered cubic structure taking place at 863oC.

Misch metal, used in lighter flints, is about 18% neodymium. The element is also used in the manufacture of artificial rubies for laser applications.

Occurrence

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 it from other rare earth elements.

Applications

Neodymium makes up about 18% of Misch metal, a material that is used to make flints for lighters. Neodymium is also a component of didymium glass, which is used to make certain types of welder's and glass blower's goggles. Neodymium is added to glass to remove the green color caused by iron contaminants.  It can also be added to glass to create violet, red or gray colors.  Some types of glass containing neodymium are used by astronomers to calibrate devices called spectrometers and other types are used to create artificial rubies for lasers. Some neodymium salts are used to color enamels and glazes.

Compounds

Neodymium compounds include

Halides Oxides
NdF3
NdCl3
NdBr3
NdI3
Nd2O3
Sulfides Nitrides
NdS
Nd2S3
NdN

Isotopes

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 (T) of >1.11019 years, 144Nd with a half-life of 2.291015 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 (T 5.5 hours), 135Ndm (T 5.5 minutes) and 141Ndm (T 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.

atom.gif (700 bytes)

Isotope  
Atomic Mass
 
Half-Life
124Nd 123.95223 ~500 ms
125Nd 124.94888 600 ms
126Nd 125.94322 ~1 seconds
127Nd 126.94050 1.8 seconds
128Nd 127.93539 ~5 seconds
129Nd 128.93319 4.9 seconds
130Nd 129.92851 21 seconds
131Nd 130.92725 33 seconds
132Nd 131.923321 1.56 minutes
133Nd 132.92235 70 seconds
133m1Nd   ~70 seconds
134Nd 133.918790 8.5 minutes
135Nd 134.918181 12.4 minutes
135mNd   5.5 minutes
136Nd 135.914976 50.65 minutes
137Nd 136.914567 38.5 minutes
137mNd   1.60 seconds
138Nd 137.911950 5.04 hours
139Nd 138.911978 29.7 minutes
139m1Nd   5.50 hours
140Nd 139.90955 3.37 days
141Nd 140.909610 2.49 hours
141mNd   62.0 seconds
142Nd 141.9077233 Stable
143Nd 142.9098143 Stable
144Nd 143.9100873 2.29 x 1015 years
145Nd 144.9125736 Stable
146Nd 145.9131169 Stable
147Nd 146.9161004 10.98 days
148Nd 147.916893 Stable
149Nd 148.920149 1.728 hours
150Nd 149.920891 6.7 x1018 years
151Nd 150.923829 12.44 minutes
152Nd 151.924682 11.4 minutes
153Nd 152.927698 31.6 seconds
154Nd 153.92948 25.9 seconds
155Nd 154.93293 8.9 seconds
156Nd 155.93502 5.49(7) seconds
157Nd 156.93903 ~2 seconds
158Nd 157.94160 ~700 ms
159Nd 158.94609 ~500 ms
160Nd 159.94909 ~300 ms
161Nd 160.95388 ~200 ms

Precautions

40px-Skull_and_crossbones.svg.jpg (1420 bytes) Neodymium has a low-to-moderate acute toxic rating; however its toxicity has not been thoroughly investigated. As with other rare earths, neodymium should be handled with care.   The metal should be kept under light mineral oil or sealed in a plastic material.

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.

80px-Flammable.jpg (2186 bytes) Neodymium metal dust is a combustion and explosion hazard.  Neodymium also acts as an anticoagulent, 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.

atom.gif (700 bytes)

Neodymium Data

 

Atomic Structure

Atomic Radius (): 2.64
Atomic Volume cm3/mol : 20.6
Covalent Radius: 1.64
Crystal Structure: Hexagonal (HEX)
Ionic Radius: 0.995

Chemical Properties

Electrochemical Equivalents: 1.7939g/amp-hr
Electron Work Function: 3.2eV
Electronegativity: 1.14 (Pauling); 1.07 (Allrod Rochow)
Heat of Fusion: 7.14kJ/mol
First Ionization Potential: 5.53
Second Ionization Potential: 10.727
Third Ionization Potential: 22.076
Valence Electron Potential: 4 -eV
Ionization Energy: 5.525 eV

Physical Properties

Atomic Mass Average: 144.24
Boiling Point: 3347K, 3074C or 5565F
Melting Point: 1294K, 1021C or 1870F
Heat of Vaporization: 273 kJ/mol
Coefficient of Lineal Thermal Expansion/K-1: 6.7E-6
Electrical Conductivity: 0.0157 106/cm
Thermal Conductivity: 0.165 W/cmK
Density: 7.01g/cm3 @ 300K
Enthalpy of Atomization: 322 kJ/mole @ 25C
Enthalpy of Fusion: 7.14 kJ/mole
Enthalpy of Vaporization: 273 kJ/mole
Molar Volume: 20.6 cm3/mole
Specific Heat: 0.19 J/gK or 0.205 J/g mol
Vapor Pressure: 0.00603 Pa @ 2617C
Estimated Crustal Abundance: 4.15101 milligrams per kilogram
Estimated Oceanic Abundance: 2.810-6 milligrams per liter

Miscellaneous

Evaporation Heat (kJ/mol): 289
First Ionizing Energy (kJ/mol): 531.5
Lattice Constant (): 3.660
Lattice C/A Ratio: 1.614