Thulium

Per Teodor Cleve c1885

Monazit - Madagaskar

Thulium is a chemical element with the symbol Tm and atomic number 69. It is a silvery-gray metal that is part of the lanthanide series of the periodic table. Thulium is the thirteenth and antepenultimate element in the lanthanide series. Despite its rarity, thulium has several applications in today's technology and scientific research.

Properties

Thulium is characterized by its bright silvery-gray luster and can be cut with a knife at room temperature. It is relatively soft and malleable, making it easy to work with in various applications. Thulium is ferromagnetic at temperatures below 32 K (−241.2 °C; −402.2 °F), paramagnetic between 32 K and 56 K, and antiferromagnetic above 56 K.

Occurrence

Thulium is the least abundant of the naturally occurring lanthanides, but it is still more common in the Earth's crust than silver. It is found in small amounts in minerals such as monazite and bastnäsite, which are often mined for their rare earth elements. The extraction and purification of thulium from these minerals require complex separation processes, typically involving solvent extraction techniques.

Applications

Despite its scarcity, thulium has several specialized applications. It is used in the production of highly efficient and durable lasers, particularly in solid-state lasers that operate at wavelengths in the infrared range. These lasers have applications in medicine, particularly in laser surgery and in the treatment of certain skin conditions. Thulium is also used in portable X-ray devices as it emits X-rays when bombarded with electrons. Additionally, thulium has potential uses in nuclear reactors as a radiation source for radiography and in the manufacturing of some electronic devices.

History

Thulium was discovered by Swedish chemist Per Teodor Cleve in 1879. Cleve named the element after Thule, a mythical place in Greek and Roman literature and cartography, which is often associated with Scandinavia or the northern regions of Europe. The discovery of thulium was part of Cleve's work on rare earth elements, during which he also identified the element holmium.

Isotopes

The most stable isotope of thulium is Tm-169, which has a half-life of about 128.6 years. It decays into ytterbium-169 through electron capture. There are also several other isotopes of thulium, all of which are radioactive and have relatively short half-lives. The isotopes of thulium range in atomic mass from 145 to 179.

Safety

Thulium compounds, as with many heavy metals, are considered to be of low to moderate toxicity, although their toxicity has not been investigated in detail. It is advisable to handle thulium compounds with care, avoiding ingestion, inhalation, or skin contact.

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