Holmium

Holmium is a chemical element with the symbol Ho and atomic number 67. It is one of the rare-earth elements and part of the lanthanide series. Holmium is a soft, silvery metal that bends easily. It does not rust easily, but it can react with air and form a yellowish coating.

Holmium is found with other rare-earth metals, like thulium. It is very rare, making up only 1.4 parts per million of the Earth's crust, about as common as tungsten. It was first found in 1878 by chemists Per Theodor Cleve, Jacques-Louis Soret, and Marc Delafontaine. The name holmium comes from Holmia, the Latin name for Stockholm.

Holmium is mostly found in minerals such as monazite and gadolinite. Its ions can glow with special light, which is used in some lasers and to color glass. Holmium is good for making very strong magnets because it has the highest magnetic permeability. It can also absorb neutrons, so it is used in nuclear reactors to help control reactions.

Properties

Holmium is the eleventh member of the lanthanide series. It is found in period 6 of the periodic table, between the lanthanides dysprosium and erbium, and above the actinide einsteinium.

Holmium is a soft, shiny metal that does not rust easily. It has special magnetic qualities, especially when cooled down. It can form strong magnetic materials when mixed with other metals like yttrium.

Holmium slowly changes when exposed to air, creating a layer that looks like rust on iron. It reacts with water and different gases to form new compounds, and it dissolves in acids to create solutions with yellow colors.

Holmium is most often found in a +3 oxidation state. Natural holmium is made of one stable type, holmium-165. Scientists have made many different types of holmium.

Compounds

Oxides and chalcogenides

Holmium(III) oxide is the only oxide of holmium. Its color changes with the light. In daylight, it looks yellowish. Under special light, it looks orange-red, like another oxide called erbium oxide. This happens because of how holmium ions give off light.

Holmium also makes other compounds called chalcogenides. One example is holmium(III) sulfide, which has orange-yellow crystals. It can form in different shapes under high pressure. Holmium(III) sulfide is made by mixing holmium(III) oxide with hydrogen sulfide at high temperatures. Holmium also makes a compound called holmium(III) selenide, which has special magnetic properties when it is very cold.

Halides

All four trihalides of holmium are known. Holmium(III) fluoride is a yellowish powder made by mixing holmium(III) oxide with ammonium fluoride. Holmium(III) chloride is made in a similar way, using ammonium chloride. These compounds have a special layered structure. Holmium also makes compounds with bromine and iodine, made by mixing holmium with these elements.

Organoholmium compounds

Main article: Organolanthanide chemistry

Organoholmium compounds act like compounds of other lanthanides. They mostly form ionic bonds and include some types of chemical structures, such as cyclopentadienides and simple alkyls and aryls, which can form long chains.

History

Holmium was first noticed in 1878 by Swiss chemists. A Swedish chemist also found it while studying another material. He named it after his hometown, Stockholm. It took many years for scientists to fully separate and study this element.

Occurrence and production

Holmium is a rare element that is never found alone in nature. It is mixed with other elements in minerals such as gadolinite and monazite. It is mainly found in China, the United States, Brazil, India, Sri Lanka, and Australia. Only about 10 kilograms of holmium are produced each year.

Holmium is a very rare part of the Earth's crust, making up just 1.3 parts per million. It can also be found in tiny amounts in soil and seawater but is almost not found in the air. It is difficult to separate holmium from other similar elements, but it can be taken from monazite sand using special methods.

Applications

Holmium is a special material that can be used in many important ways. For example, it helps scientists check how well machines that measure light work. It can also create very strong magnetic fields, which are useful in making tiny magnets.

Holmium is used in certain types of lasers that help doctors perform precise surgeries. It can also be used to help treat some kinds of cancer and improve medical imaging. Scientists are studying how it might help build future computers.

Biological role and precautions

Holmium does not have a role in human biology, but its salts can help speed up some body processes. People usually get about a milligram of holmium each year from their food. Plants generally do not take in much holmium from the soil. Some vegetables have been found to have tiny amounts of holmium, but this is usually not a problem.

Holmium and its soluble salts can be harmful if eaten, but insoluble holmium salts are not dangerous. Holmium dust can catch fire or cause explosions. If large amounts of holmium salts are breathed in, eaten, or put into the body, they can cause serious harm. The long-term effects of holmium on the body are still unknown, and it is thought to have low immediate harm from short exposure.