Difference between revisions of "Neodymium"

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{{Infobox element
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<!-- General properties -->
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|name=Neodymium
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|symbol=Nd
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|pronounce=
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|pronounce 2=
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|alt name=
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|alt names=
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|allotropes=
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|appearance=Silvery white
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<!-- Periodic table -->
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|above=
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|below=[[Uranium|U]]
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|left=[[Praseodymium]]
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|right=Promethium
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|number=60
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|atomic mass=144.242(3)
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|atomic mass 2=
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|group=
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|period=6
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|period ref=
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|period comment=
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|block=f
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|block ref=
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|block comment=
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|electron configuration= [Xe] 4f<sup>4</sup> 6s<sup>2</sup>
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|electron configuration ref=
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|electron configuration comment=
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|electrons per shell=2, 8, 18, 22, 8, 2
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|electrons per shell ref=
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|electrons per shell comment=
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<!-- Physical properties -->
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|physical properties comment=
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|color=Silvery-white
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|phase=Solid
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|phase ref=
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|phase comment=
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|melting point K=1297
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|melting point C=1024
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|melting point F=​1875
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|melting point ref=
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|melting point comment=
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|boiling point K=3347
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|boiling point C=3074
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|boiling point F=5565
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|sublimation point K=
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|sublimation point C=
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|density gplstp=
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|density gpcm3nrt=7.01
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|density gpcm3mp=6.89
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|density gpcm3bp=
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|molar volume=
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|triple point K=
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|triple point kPa=
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|critical point K=
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|critical point MPa=
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|heat fusion=7.14
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|heat fusion ref=
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|heat vaporization=289
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|heat vaporization ref=
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|heat vaporization comment=
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|heat capacity=27.45
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|heat capacity ref=
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|heat capacity comment=
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|heat capacity 2=
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|heat capacity 2 ref=
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|heat capacity 2 comment=
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|vapor pressure 1=1595
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|vapor pressure 10=1774
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|vapor pressure 100=1998
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|vapor pressure 1 k=(2296)
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|vapor pressure 10 k=(2715)
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|vapor pressure 100 k=(3336)
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|vapor pressure ref=
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|vapor pressure 1 2=
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|vapor pressure 1 k 2=
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|vapor pressure 2 comment=
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<!-- Atomic properties -->
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|atomic properties comment=
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|oxidation states='''+4''', '''+3''', +2
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|oxidation states ref=
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|oxidation states comment=(a mildly basic oxide)
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|electronegativity=1.14
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|electronegativity ref=
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|electronegativity comment=
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|ionization energy 1=533.1
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|ionization energy 1 ref=
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|ionization energy 1 comment=
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|ionization energy 2=1040
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|ionization energy 2 ref=
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|ionization energy 2 comment=
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|ionization energy 3=2130
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|ionization energy 3 ref=
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|ionization energy 3 comment=
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|number of ionization energies=
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|ionization energy ref=
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|ionization energy comment=
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|atomic radius=181
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|atomic radius ref=
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|atomic radius comment=
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|atomic radius calculated=
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|atomic radius calculated ref=
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|atomic radius calculated comment=
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|covalent radius=201±6
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|covalent radius ref=
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|covalent radius comment=
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|Van der Waals radius=
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<!-- Miscellanea -->
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|crystal structure=
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|crystal structure prefix=
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|crystal structure ref=
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|crystal structure comment=Double hexagonal close-packed (dhcp)
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|crystal structure 2=
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|speed of sound=
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|speed of sound comment=
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|speed of sound rod at 20=2330
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|speed of sound rod at r.t.=
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|speed of sound rod at r.t. ref=
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|thermal expansion=9.6
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|thermal expansion ref=
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|thermal expansion comment=(α, poly)
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|thermal expansion at 25=
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|thermal expansion at 25 ref=
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|thermal expansion at 25 comment=
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|thermal conductivity=16.5
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|electrical resistivity=6.43·10<sup>-7</sup>
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|electrical resistivity comment=(α, poly)
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|band gap=
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|Curie point K=
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|magnetic ordering=Paramagnetic
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|magnetic ordering ref=
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|tensile strength=
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|tensile strength ref=
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|tensile strength comment=
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|Young's modulus=41.4
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|Young's modulus ref=
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|Young's modulus comment=(α form)
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|Shear modulus=16.3
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|Shear modulus ref=
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|Shear modulus comment=(α form)
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|Bulk modulus=31.8
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|Bulk modulus ref=
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|Bulk modulus comment=(α form)
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|Poisson ratio=0.281
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|Poisson ratio ref=
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|Poisson ratio comment=(α form)
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|Mohs hardness=
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|Vickers hardness=345–745
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|Vickers hardness comment=
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|Brinell hardness=265–700
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|CAS number=7440-00-8
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<!-- History -->
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|prediction date=
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|discovered by= Carl Auer von Welsbach
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|discovery date=1885
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<!-- Isotopes -->
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|isotopes=
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|engvar=
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}}
 
'''Neodymium '''is a [[lanthanide]] with the symbol '''Nd''' and atomic number 60. Also classified as a [[rare earth metal]], it is a silvery solid that tarnishes quickly in air and will completely corrode to a pink oxide powder if stored improperly. Its most common use is in high-strength [[Neodymium iron boron magnet|neodymium magnets]]. As a tripositive ion, neodymium has unusually narrow absorption bands and will undergo color changes depending on the light source.
 
'''Neodymium '''is a [[lanthanide]] with the symbol '''Nd''' and atomic number 60. Also classified as a [[rare earth metal]], it is a silvery solid that tarnishes quickly in air and will completely corrode to a pink oxide powder if stored improperly. Its most common use is in high-strength [[Neodymium iron boron magnet|neodymium magnets]]. As a tripositive ion, neodymium has unusually narrow absorption bands and will undergo color changes depending on the light source.
  

Revision as of 18:23, 20 October 2017

Neodymium,  60Nd
General properties
Name, symbol Neodymium, Nd
Appearance Silvery white
Neodymium in the periodic table

↑
Nd
↓
U
Praseodymium ← Neodymium → Promethium
Atomic number 60
Standard atomic weight (Ar) 144.242(3)
Group, block , f-block
Period period 6
Electron configuration [Xe] 4f4 6s2
per shell
 2, 8, 18, 22, 8, 2
Physical properties
Silvery-white
Phase Solid
Melting point 1297 K ​(1024 °C, ​​1875 °F)
Boiling point 3347 K ​(3074 °C, ​5565 °F)
Density near r.t. 7.01 g/cm3
when liquid, at  6.89 g/cm3
Heat of fusion 7.14 kJ/mol
Heat of 289 kJ/mol
Molar heat capacity 27.45 J/(mol·K)
 pressure
Atomic properties
Oxidation states +4, +3, +2 ​(a mildly basic oxide)
Electronegativity Pauling scale: 1.14
energies 1st: 533.1 kJ/mol
2nd: 1040 kJ/mol
3rd: 2130 kJ/mol
Atomic radius empirical: 181 pm
Covalent radius 201±6 pm
Miscellanea
Crystal structure ​Double hexagonal close-packed (dhcp)
Speed of sound thin rod 2330 m/s (at 20 °C)
Thermal expansion 9.6 µm/(m·K) (α, poly)
Thermal conductivity 16.5 W/(m·K)
Electrical resistivity 6.43·10-7 Ω·m (α, poly)
Magnetic ordering Paramagnetic
Young's modulus 41.4 GPa (α form)
Shear modulus 16.3 GPa (α form)
Bulk modulus 31.8 GPa (α form)
Poisson ratio 0.281 (α form)
Vickers hardness 345–745 MPa
Brinell hardness 265–700 MPa
CAS Registry Number 7440-00-8
History
Discovery Carl Auer von Welsbach (1885)
· references

Neodymium is a lanthanide with the symbol Nd and atomic number 60. Also classified as a rare earth metal, it is a silvery solid that tarnishes quickly in air and will completely corrode to a pink oxide powder if stored improperly. Its most common use is in high-strength neodymium magnets. As a tripositive ion, neodymium has unusually narrow absorption bands and will undergo color changes depending on the light source.

Properties

Physical properties

Neodymium is a silvery metal that is about as dense as tin. Older samples that have been exposed to air show corrosion, which will appear bluish. Although the metal is known for its use in powerful magnets, it is only slightly paramagnetic and cannot be lifted by a neodymium magnet. It may be possible to observe the magnetism by placing a small piece on a styrofoam block and allowing it to move toward a magnet.

Neodymium salts undergo large and dramatic color changes under different light sources. Under incandescent light or sunlight, which consist of continuous spectra, neodymium salts generally appear pink or purple. Fluorescent lighting consists of only a few specific energies of light which do not match the absorption bands of neodymium salts, thus causing the compounds to appear colorless. Holmium compounds will undergo similar color changes.

Chemical properties

Neodymium metal is rather reactive, and a centimeter-sized sample will corrode within a year on exposure to air. Thus, the metal must be stored under oil or in an ampoule filled with argon. The metal reacts only slowly with water, but reacts vigorously with acids and the halogens to form neodymium salts. Most neodymium salts are soluble in water except for the fluoride and oxalate. Neodymium oxide and hydroxide are insoluble in water, but will absorb carbon dioxide from the air to form neodymium carbonate. All three of these compounds are insoluble in water, but will readily dissolve in acids.

Neodymium sulfate is notable for its inverse solubility curve, which causes the salt to precipitate at high temperatures. It is nearly impossible to redissolve after being precipitated. The double sulfate of potassium and neodymium is less soluble than neodymium sulfate itself. Different preparations of neodymium sulfate have given different colors, possibly due to the formation of acid and basic sulfates.

Most lanthanides do not form complexes easily, but there is evidence for a possible chloride complex.

Availability

Pure neodymium metal can be bought from Metallium. It is sold as 5 and 50 gram sizes, as well as rods, ampoules, and coins.

Preparation

The most common source of neodymium is neodymium magnets. It's difficult, however, to extract the neodymium from the magnets, and a procedure to produce pure neodymium metal from neodymium fluoride with either calcium or lithium as the reducer is still in development.

Projects

  • Color changing crystals
  • Color changing glass
  • Extracting neodymium from magnets

Safety

Storage

Neodymium metal must be stored away from air and water. Ampouling the metal is a viable long-term storage solution. Storing the metal under mineral oil is an ideal short-term solution, but air will still diffuse through the oil anyway. Unlike europium, the reaction with water is not violent.

Toxicity

Neodymium compounds do not appear to be very toxic. They act similarly to calcium ions within the body. However, research on the toxicity neodymium compounds is not complete, and they should be handled with general safety precautions in place.

Flammability

Neodymium is somewhat flammable and may spark when struck. Powdered neodymium may ignite very easily. Class D fire extinguishers should be used against neodymium fires. Water may aggravate a neodymium fire and should never be used.

References

Relevant Sciencemadness threads

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