Holmium

67

dysprosium ← holmium → erbium


-
↑
Ho
↓
Es




periodic table




General


Name, Symbol, Number

holmium, Ho, 67


Chemical series
lanthanides


Group, Period, Block

n/a, 6, f


Appearance
silvery white 



Atomic mass
164.93032(2) g/mol


Electron configuration
[Xe] 4f11 6s2


Electrons per shell
2, 8, 18, 29, 8, 2


Physical properties


Phase
solid


Density (near r.t.)
8.79 g/cm³


Liquid density at m.p.
8.34 g/cm³


Melting point
1734 K
(1461 °C, 2662 °F)


Boiling point
2993 K
(2720 °C, 4928 °F)


Heat of fusion
17.0 kJ/mol


Heat of vaporization
265 kJ/mol


Heat capacity
(25 °C) 27.15 J/(mol·K)




Vapor pressure


P/Pa
1
10
100
1 k
10 k
100 k


at T/K
1432
1584
(1775)
(2040)
(2410)
(2964)



Atomic properties


Crystal structure
hexagonal


Oxidation states
3
(basic oxide)


Electronegativity
1.23 (Pauling scale)


Ionization energies
(more)

1st: 581.0 kJ/mol


2nd: 1140 kJ/mol


3rd: 2204 kJ/mol


Atomic radius
175 pm


Miscellaneous


Magnetic ordering
no data


Electrical resistivity
(r.t.) (poly) 814 nΩ·m


Thermal conductivity
(300 K) 16.2 W/(m·K)


Thermal expansion
(r.t.) (poly)
11.2 µm/(m·K)


Speed of sound (thin rod)
(20 °C) 2760 m/s


Speed of sound (thin rod)
(r.t.) 64.8 m/s


Shear modulus
26.3 GPa


Bulk modulus
40.2 GPa


Poisson ratio
0.231


Vickers hardness
481 MPa


Brinell hardness
746 MPa


CAS registry number
7440-60-0


Notable isotopes




Main article: Isotopes of holmium


iso

NA

half-life

DM

DE (MeV)

DP


163Ho

syn

4570 a

ε

0.003

163Dy


164Ho

syn

29 min

ε

0.987

164Dy


165Ho

100%

Ho is stable with 98 neutrons


166Ho

syn

26,763 h

β-

1.855

166Er


167Ho

syn

3,1 h

β-

1.007

167Er


Holmium (chemical symbol Ho, atomic number 67) is a relatively soft, silvery-white metallic element that is stable in dry air at room temperature. It is a member of the lanthanide series of chemical elements and is also considered one of the "rare earth metals."[1]

Contents

1 Occurrence and isolation
2 History
3 Notable characteristics

3.1 Isotopes


4 Compound
5 Applications
6 Precautions
7 See also
8 Notes
9 References
10 External links
11 Credits



Of all the naturally occurring elements, holmium has the highest magnetic moment. It has therefore been used in high-strength magnets to create the strongest artificially generated magnetic fields. In addition, it is suitable for placement in yttrium-iron-garnet (YIG) and yttrium-lanthanum-fluoride (YLF) solid state lasers found in microwave equipment used for medical and dental procedures. Holmium is also useful in nuclear control rods to absorb neutrons produced by nuclear fission reactions and in a certain type of laser to break up kidney stones. Holmium oxide is used as a yellow glass coloring.

Occurrence and isolation
Like the other rare earth elements, holmium is not found as a free element in nature. It occurs combined with other elements in rare-earth minerals, particularly gadolinite and monazite. Its estimated abundance in the Earth's crust is 1.3 milligrams per kilogram.
Holmium is commercially extracted by ion-exchange from monazite sand (0.05 percent holmium), but it remains difficult to separate from other rare earth elements. It has been isolated by the chemical reduction of its anhydrous chloride or fluoride with metallic calcium.

History
Holmium was discovered by Marc Delafontaine and Jacques-Louis Soret in 1878, when they noticed its unique spectral bands in an absorption spectrum. They called it "Element X." Later that year, Per Teodor Cleve independently discovered the element while working on erbia earth (erbium oxide).
Using a method developed by Carl Gustaf Mosander, Cleve first removed all the known contaminants from erbia and obtained two new materials, one yellowish brown and one green. He named the brown substance holmia (the Latin name for Cleve's hometown, Stockholm), and he called the green one thulia. Holmia was later found to be holmium oxide, and thulia was thulium oxide.

Notable characteristics
Holmium is an inner transition metal (or lanthanide) that lies in period six of the periodic table, between dysprosium and erbium. This relatively soft, malleable element is fairly corrosion-resistant and stable in dry air at standard temperature and pressure. In moist air and at higher temperatures, however, it quickly  oxidizes to form a yellowish oxide. In its pure form, it has a bright silvery luster.
In combining with other elements, holmium exhibits a trivalent character (oxidation number of +3). It has unusual magnetic properties, including the highest magnetic moment (10.6µB) of any naturally occurring element. When combined with yttrium, it forms highly  magnetic compounds.

Isotopes
Natural holmium contains one stable isotope, holmium 165. Many synthetic radioactive isotopes are known, of which the most stable one is holmium 163, with a half-life of 4,570 years. All other radioisotopes have half-lives less than 27 hours, and most have half-lives under three hours.

Compound
Holmium(III) oxide (Ho2O3): This yellow solid was first isolated by Cleve from an impure sample of erbia, as mentioned above. Along with dysprosium(III) oxide (Dy2O3), it is among the most powerfully paramagnetic substances known. It is sometimes used in making specialty glasses.
Applications
Given its unique magnetic properties, holmium has been used to create the strongest artificially generated magnetic fields when placed in high-strength magnets as a magnetic pole piece (also called a magnetic flux concentrator).
Its very high magnetic moment is suitable for use in yttrium-iron-garnet (YIG) and yttrium-lanthanum-fluoride (YLF) solid state lasers found in microwave equipment that is used for medical and dental procedures.
As it can absorb neutrons from nuclear fission reactions, the element is also used in nuclear control rods.
Holmium is used in a laser to break up kidney stones while being minimally invasive.
Holmium oxide is used as a yellow glass coloring.
Precautions
As with other rare earths, holmium appears to have a low rating for acute toxicity. It plays no biological role in humans but may be able to stimulate metabolism.

See also
Chemical element
Inner transition metal
Laser
Magnetism
Metal
Periodic table
Yttrium
Notes

↑ The term "rare earth metals" (or "rare earth elements") is a trivial name applied to 16 chemical elements: scandium, yttrium, and 14 of the 15 lanthanides (excluding promethium), which occur naturally on Earth. Some definitions also include the actinides. The word "earth" is an obsolete term for oxide. The term "rare earth" is discouraged by the International Union of Pure and Applied Chemistry (IUPAC), as these elements are relatively abundant in the Earth's crust.


ReferencesISBN links support NWE through referral fees
Chang, Raymond. 2006. Chemistry. 9th ed. New York: McGraw-Hill Science/Engineering/Math. ISBN 0073221031
Cotton, F. Albert, and Geoffrey Wilkinson. 1980. Advanced Inorganic Chemistry. 4th ed. New York: Wiley. ISBN 0-471-02775-8
Greenwood, N.N. and A. Earnshaw. 1998. Chemistry of the Elements. 2nd ed. Oxford, U.K.; Burlington, MA: Butterworth-Heinemann, Elsevier Science. ISBN 0750633654 Online version
"Holmium" Los Alamos National Laboratory, Chemistry Division. Retrieved October 8, 2007.
Holmium It's Elemental, Jefferson Lab. Retrieved October 8, 2007.
Jones, Adrian P., Frances Wall, and C. Terry Williams, eds. 1996. Rare Earth Minerals: Chemistry, Origin and Ore Deposits. The Mineralogical Society Series. London, UK: Chapman and Hall. ISBN 0412610302
Stwertka, Albert. 1998. Guide to the Elements. Rev. ed. Oxford, UK: Oxford University Press. ISBN 0-19-508083-1
External links
All links retrieved January 12, 2018.

Holmium WebElements.com.
Holmium American Elements.

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