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Holmium

What is Holmium

Holmium (pronunciation: HOHL-mee-em) is a silvery metal belonging to the group of lanthanides and represented by the chemical symbol Ho [1, 2]. It has one stable naturally occurring isotope, 165Ho, with a natural abundance of 100% while its most stable radioisotope, 163Ho has a half-life period of 4,570 years [3].

Holmium

Where is Holmium Found

Although Holmium does not freely occur in nature, it is found as a component in several minerals including bastnaesite and monazite [1, 4]. Commercially, it is obtained from monazite, bastnaesite, and xenotime ores through ion exchange and is isolated by calcium reduction of its anhydrous fluoride [1, 4, 5]. While top 3 holmium producing countries include China, Russia, and Malaysia, the top 3 nations with the largest holmium holdings in the world are China, the CIS countries, and the USA [1].

History

Origin of its Name: It is derived from ‘Holmia’, the Latin name for the Swedish capital Stockholm [1].

Who discovered it: Holmium was discovered by the Swedish chemist Per Teodor Cleve, and independently by the Swiss chemist Louis Soret along with Marc Delafontaine [1].

When and How was it Discovered

In 1878, Louis Soret and Marc Delafontaine while investigating yttrium at Geneva found that it was contaminated with other lanthanoids, observing unexplained spectral lines [1, 4]. They extracted a new element ‘X’, which is now known as holmium [4]. In that same year, Per Teodor Cleve worked with erbium at Uppsala to discover a brown and a green substance, which he named holmia (holmium oxide) and thulia (thulium oxide) respectively [4].

The pure form of holmium was separated by the Swedish botanist Otto Holmberg [4].

Holmium Symbol

Holmium Identification

Atomic number 67 [1]
CAS number 7440-60-0 [1]
Position in the periodic table Group Period Block
  Lanthanides [1] 6 [1] f [1]

Properties and Characteristics of Holmium

General Properties

Atomic mass 164.930 amu [1]
Relative atomic mass 164.930 [1]

Physical Properties

Color Bright silvery-white [1, 4]
Melting point/freezing point 1472 °C, 2682 °F [1]
Boiling point 2700 °C, 4892 °F [1]
Density 8.80 g cm-3 [1]
State of matter at room temperature (solid/liquid/gas) Solid [1, 4]
Hardness
– Brinell 746 MPa [6]
– Mohs 1.65 [6]
– Vickers 481 MPa [6]
Electrical conductivity 1.1X106 S/m [6]
Thermal (heat) conductivity 16 W/(m K) [6]
Specific heat 165 J kg-1 K-1 [1]
Bulk modulus 40.2 GPa [1]
Shear modulus 26.3 GPa [1]
Young’s modulus 64.8 GPa [1]
Vapor pressure
– Temperature (K) 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
– Pressure (Pa) 3.20 X 10-9 2.32 X 10-5 8.37 X 10-3 0.546 12.3

Chemical Properties

Oxidation states 3 [1]
Isotopes Isotope Mass Abundance (%) Half-life Mode of decay
  165Ho 164.930 100

Atomic Data of Holmium (Element 67)

Valence electrons 2 [7]
Quantum numbers
– n 4 [7]
– ℓ 3 [7]
– m 0 [7]
– ms -1/2 [7]
Electron configuration (noble gas configuration) [Xe] 4f116s2 [1]
Atomic structure
– Number of electrons 67 [4]
– Number of neutrons 98 [4]
– Number of protons 67 [4]
Radius of Atom
– Atomic radius 2.30 Å [1]
– Covalent radius 1.79 Å [1]
Electronegativity (Pauling-scale) 1.23 [1]
Electron affinity Unknown [1]
Ionization energy (kJ mol-1) 1st 2nd 3rd 4th 5th 6th 7th 8th
  580.987 1138.5 2203.73 4100.6

Holmium Electron Configuration (Bohr Model)

How is Holmium Used

  • Since it is an excellent absorber of neutrons, its isotopes are used in the control rods of nuclear reactors to control fission chain reactions [1, 4].
  • Holmium has special magnetic properties, and so its alloys are used for producing magnets and flux concentrators for high-intensity magnetic fields [4].
  • Holmium-doped solid-state lasers are used for medical procedures including breaking-up of kidney stones (lithotripsy), and benign prostatic hyperplasia surgeries like prostate enucleation (HoLEP), resection (HoLRP), and ablation (HoLAP) [4, 8].
  • Holmium oxide or holmia can be used as a red or yellow coloring agent for cubic zirconia and glass [4].

Holmium Element 67

Holmium Toxicity

The element 67 is not considered to be harmful because it has low toxicity [4]. However, holmium salts can be toxic if orally consumed, inhaled, or injected in large amounts [9].

Interesting Facts

  • Holmium is graphically represented by an image of the coat of arms of Stockholm, the Swedish capital after which the element is named [1].
  • The element quickly oxidizes at high temperatures and in the moist air [5].

Holmium Laser System Lithotripsy

Cost of Holmium

The cost of pure holmium is $8.6 per gram and $8600 per kg [4], but in bulk, its price is $10 per gram [10].

References

  1. http://www.rsc.org/periodic-table/element/67/holmium
  2. https://education.jlab.org/itselemental/ele067.html
  3. https://www.webelements.com/holmium/isotopes.html
  4. https://www.chemicool.com/elements/holmium.html
  5. https://www.livescience.com/38360-facts-about-holmium.html
  6. http://www.periodictable.com/Elements/067/data.html
  7. http://chemistry-reference.com/q_elements.asp?Symbol=Ho&language=en
  8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4526611/
  9. http://nautilus.fis.uc.pt/st2.5/scenes-e/elem/e06740.html
  10. https://hobart.k12.in.us/ksms/PeriodicTable/holmium.htm

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