How Does Holmium Impact Chemistry and Everyday Life?
With an Atomic Mass of 164.9303, the chemical element Ho (Holmium) is one of the rarest compounds on earth. Holmium proves excellences in terms of malleability and ductility. This is a white-coloured, silvery textured soft material that possesses unusual magnetic characteristics. From nuclear control reaction procedures to medical treatment options that are non-invasive to a patient, Holmium plays a key role in many real-time applications. Known for its high significance, let us learn about this element Ho, by understanding its properties, chemical nature, examples, and a few important applications.
Important Details about What Holmium is
‘Per Teodor Cleve’ (1840-1905) was the 1st Swedish chemist, who discovered Holmium spectroscopically in 1879 when working with another earth metal ‘Erbium’. The name was assigned for his place of birth named Uppsala in Stockholm, Sweden.
Holmium is one of the rarest elements found on earth and is categorized as lanthanides. The element Ho is located in the 67th position in the periodic table. This is a silver, shiny material but turns yellowish oxide (Ho2O3), during the process of oxidation or when heated directly. Being completely soluble in acids, Holmium gets affected due to the presence of oxygen and water.
As we noted before, the element Holmium has unusual magnetic potential and it also records the highest magnetic moment ever, which is 10.6 µB for a naturally-derived chemical substance.
Let us now quickly understand the physical and chemical properties of Holmium from the following.
Physical and Chemical Properties of the Element Ho
Firstly, here are the physical properties of Holmium.
A key rarest element found on earth. But it is more common than silver and gold.
Soft and silvery in texture and appearance.
Is both malleable and ductile.
Amount of Ho available inside the crust of the earth is approximated to be 0.7 to 1.2 parts per million. But mined in a few countries such as India, the United States of America, Sri Lanka, China, Australia and Brazil, in reserves estimated to be around 400,000 tonnes.
Hexagonal close-packed (hcp) is the crystal structure of Ho.
Forms an alloy when combined with other metals.
High temperature is proportional to its high reactivity.
HOL-me-um is the pronunciation.
Holmium possesses unusual attractive properties along with electrical conductivity, and majorly seen at times of low-temperature conditions.
Gadolinite and Monazite are the rarest isotopes of Ho.
Now, we have Some Important Chemical Properties.
[Xe] 4f11 6s2 is the Electronic Configuration of Ho.
The atomic number is 67 and the atomic mass is 164.9303.
Noted in the periodic table at Row 6.
Present in the section of Lanthanides in the f-block of the periodic table.
Solid structure at 20°C celsius.
Somewhat electropositive.
Stability in room temperature.
Trivalently bonded.
1.23 is the Electronegativity as per the Pauling scale.
2,720°C (4,930°F) is the Boiling Point and Melting Point is 1,470°C (2,680°F).
8.803 grams is the Density of Ho per 1 Cubic Centimetre.
Good desolvation in other acids, similar to other metals.
A gist about the Isotopes and Extraction of Holmium
An isotope is defined to be the more than 2 forms of a chemical element. For the element Ho, there is only 1 naturally-existing isotope which is holmium-165. Holmium-163 is a synthetic isotope with a half-life of 4570 years.
There is a minimum count of 20 isotopes of Holmium that are found to be radioactive. However, there is no proven cases or enough scientific evidence about the health issues or safety measures for using Holmium to date.
When there is a chemical ration between Holmium Fluoride (HoF3) and the Calcium metal, then this process gives rise to Holmium (Ho).
The Significant Applications of Holmium
Even though the element is radioactive and there is no proven record for its toxicity (generally stated to be Low) there are enough applications for using Ho in industries and other research fields. Given below are some important applications of Holmium in real-life.
Holmium acts as a Flux concentrator to many high magnetic fields and also, this is used as an alloy in the production and manufacturing of magnets.
The rods of nuclear control reactors make use of Holmium considering its good neutron absorption capacity. Moreover, the same absorption power of Ho makes it suitable for use as a burnable poison.
For Cubic Zirconia and Glass production, the Holmia also called the holmium oxide, is preferred for giving a natural yellow and red colouration.
To calibrate things, optical spectrophotometers prefer Holmium.
The pole pieces of several static magnets make use of this powerful element Ho, owing to its high permeability.
For non-invasive medical processes, the element Ho is used in the case of solid-state specialized lasers for programs such as cancer treatment, fibre-optics, dental operations, and even for kidney stones.
Holmium is majorly used in the treatment procedures of the eye disorder glaucoma, and even to correct failed or wrong glaucoma surgeries. Holmium lasers come handy for reducing the abnormal range of pressure in human eyes.
In the future, with enough research for its quantum property, one can utilize Holmium for quantum computers and other classical control methods.
Conclusion
Holmium (Ho) is a silver, rare earth metal, with the atomic number 67 and present in the 6th row, f-block of the periodic table. The element is categorized under the lanthanides. It has unusual electrical and magnetic properties and is used in nuclear reactors for its good absorption power. The reactivity of Ho is high at increased temperatures but usually stable at room temperature. Holmium-165 is the only naturally-occurring isotope but there are 20 radioactive isotopes noted for Ho. The toxicity of this element is still not known completely but there is a good number of applications for Holmium in the fields of medicine and dental procedures.
FAQs on Holmium: Properties, Isotopes, and Applications
1. What are the key physical and chemical properties of holmium?
Holmium (Ho) is a rare-earth element with atomic number 67. Its key properties include:
- Physical Properties: It is a bright, silvery, relatively soft, and malleable metal. It is stable in dry air at room temperature but oxidizes to form a yellowish oxide in moist air or at higher temperatures.
- Chemical Properties: As a typical lanthanide, it predominantly forms the +3 oxidation state. It reacts slowly with cold water and more rapidly with hot water to form holmium hydroxide. It also reacts with all halogens to form holmium(III) halides.
- Magnetic Properties: It possesses the highest magnetic moment (10.6 µB) of any naturally occurring element, making it strongly paramagnetic.
2. What is the electron configuration of holmium and what does it imply about its chemical behaviour?
The electron configuration of holmium (Ho) is [Xe] 4f¹¹ 6s². This configuration is significant for two main reasons:
- The two electrons in the outermost 6s orbital are the first to be lost during chemical reactions, followed by one from the 4f orbital, leading to the highly stable +3 oxidation state, which is characteristic of most lanthanides.
- The partially filled 4f orbital, with its unpaired electrons, is responsible for holmium's remarkable magnetic properties and the characteristic colours of its compounds.
3. What are the major applications of holmium in technology and medicine?
Holmium's unique properties make it valuable in several high-tech and medical fields. Its major applications include:
- High-Strength Magnets: It is used as a magnetic flux concentrator to create some of the strongest artificially generated magnetic fields.
- Medical Lasers: Holmium-doped YAG (Ho:YAG) lasers are critical in medicine for procedures like breaking up kidney and bladder stones (lithotripsy) and in orthopaedic surgery, as their infrared light is strongly absorbed by water in tissues.
- Nuclear Reactors: As an excellent neutron absorber, holmium is used in nuclear control rods to manage the rate of fission reactions.
- Glass and Crystal Colouring: Holmium oxide (Holmia) is used as a colorant to give glass and cubic zirconia a distinct yellow or red colour, depending on the lighting.
4. Why does holmium exhibit such powerful magnetic properties?
Holmium's exceptional magnetic strength, the highest of any natural element, stems directly from its electronic structure. It has a magnetic moment of 10.6 Bohr magnetons (µB). This is because the arrangement of electrons in its 4f subshell results in a large number of unpaired electrons. The combined effect of the spin and orbital angular momentum of these 4f electrons creates an extremely powerful atomic magnetic field, making holmium strongly paramagnetic at ambient temperatures and ferromagnetic at very low temperatures (below 19 K).
5. How is holmium metal isolated from its ores?
Holmium is typically found in minerals like monazite and gadolinite alongside other rare-earth elements. After initial separation from other elements, a common method for isolating pure holmium metal is the reduction of its halide with calcium metal. Anhydrous holmium(III) fluoride (HoF₃) is heated with calcium (Ca) in a tantalum crucible. The more reactive calcium displaces the holmium, producing pure holmium metal and calcium fluoride slag, as shown in the reaction: 2HoF₃ + 3Ca → 2Ho + 3CaF₂.
6. What are the isotopes of holmium and which one is important for medical use?
Holmium has only one stable, naturally occurring isotope, holmium-165 (¹⁶⁵Ho), which makes up 100% of its natural abundance. All other isotopes are radioactive. The most significant synthetic radioisotope is holmium-166 (¹⁶⁶Ho). With a half-life of approximately 27 hours, it is used in nuclear medicine for the radiotherapy of cancers and for treating arthritis, as it emits beta particles that can destroy targeted cells.
7. How does the metamerism of holmium oxide cause its colour to change under different lights?
Holmium(III) oxide (Ho₂O₃), or holmia, shows a striking property called metamerism, appearing as different colours under different lighting. This is an optical effect, not a chemical change. Holmia has extremely sharp absorption bands in the visible spectrum, meaning it absorbs very narrow ranges of light colour.
- Under natural daylight, which has a continuous spectrum, the light reflected gives it a yellowish colour.
- Under fluorescent lighting, which often has distinct peaks of emission (e.g., green and red), holmia's sharp bands absorb some of these peaks, altering the balance of reflected light and causing it to appear pinkish-red.
8. How does holmium react with common substances like water and halogens?
As a reactive lanthanide, holmium reacts with many common substances:
- Reaction with Water: It reacts slowly with cold water but more readily with hot water to form holmium hydroxide (Ho(OH)₃) and hydrogen gas: 2Ho (s) + 6H₂O (l) → 2Ho(OH)₃ (aq) + 3H₂ (g).
- Reaction with Halogens: Holmium metal reacts with all halogens (fluorine, chlorine, bromine, iodine) when heated to form the corresponding holmium(III) halides. For instance, its reaction with chlorine gas produces holmium(III) chloride: 2Ho (s) + 3Cl₂ (g) → 2HoCl₃ (s).
