Yttrium (Y)
Yttrium (Y) is a metallic element with the atomic number 39 and is classified as a transition metal, distinguishing it from other rare earth elements that typically belong to the lanthanide series. It was first discovered in the late 18th century from a mineral known as ytterbite in Sweden, which contained a previously unknown substance that was later identified as yttrium. This element is soft, silvery-white, and reactive, forming a protective oxide layer when exposed to air, although it can ignite under certain conditions.
Yttrium is primarily extracted from rare earth minerals, such as monazite and gadolinite, and is the fortieth most abundant element in the Earth's crust. It has several important industrial applications, particularly in high-tech fields. For instance, yttrium oxide is crucial in creating phosphors for red color in television tubes and LED screens, while yttrium is used to enhance the strength of various metal alloys.
Moreover, the radioactive isotope yttrium-90 plays a significant role in medicine, being utilized in treatments for certain cancers and in advanced surgical tools. Despite its various uses, yttrium serves no major biological function and can be toxic if inhaled or improperly managed in the environment, highlighting the need for careful handling.
Yttrium (Y)
- Element Symbol: Y
- Atomic Number: 39
- Atomic Mass: 88.9059
- Group # in Periodic Table: 3
- Group Name: Transition metals
- Period in Periodic Table: 5
- Block of Periodic Table: d-block
- Discovered by: Johan Gadolin (1789)
Yttrium is a metallic chemical element of the periodic table. It is a rare earth element, although unlike most other rare earth elements, it does not belong to the lanthanide group of elements. Instead, yttrium is classified as a transition metal. Rare earth elements typically occur together in nature and are oftentimes difficult to separate. Yttrium was the first of the rare earth elements to be discovered.
In 1787 Carl Arrhenius discovered a mineral in a quarry outside the small Swedish town of Ytterby. He sent a sample of this mineral, named ytterbite in honor of the town where it was discovered, to Finnish chemist Johan Gadolin. After analyzing the sample, Gadolin found that the mineral contained amounts of silica, alumina, and beryllium oxide, as well as 38 percent of an then-unknown substance—yttrium. In honor of Gadolin and his discoveries, ytterbite was renamed in 1800 to gadolinite. Gadolin’s sample of yttrium was impure, however, and contained eight other oxides of rare earth metals. In 1828 German chemist Friedrich Wöhler produced an impure yttrium metal, but it was not until 1953 that Frank Spedding of the Ames Laboratory in Iowa produced the purest yttrium metal. In total there are four elements named for the town of Ytterby, Sweden: yttrium, ytterbium, terbium, and erbium.
Physical Properties
Yttrium has a silvery-white color. At 298 kelvins (K), its standard state is a soft solid, with a density of 4.48 grams per cubic centimeter (g/cm3). Yttrium is susceptible to corrosion when exposed to air and quickly develops a protective oxide coating on its surface. This film makes yttrium relatively stable in air, but in fine amounts such as shavings, yttrium metal can spontaneously ignite if heated to temperatures of 400 degrees Celsius (°C) or above.
The melting point of yttrium is 1522 °C. Its boiling point is 3345 °C. The specific heat of yttrium is relatively high, at 298 joules per kilogram-kelvin (J/kg·K). Yttrium is a good conductor, with an electrical conductivity of 1.8 × 106 siemens per meter (S/m). It has a thermal conductivity of 17 watts per meter-kelvin (W/m·K). Yttrium is paramagnetic, which means that it is magnetized when placed within a magnetic field, but it does not retain this property upon removal.
Chemical Properties
The most common oxidation state of yttrium is +3. Yttrium reacts readily with water, decomposing it to a hydrogen gas, and it also reacts with mineral acids. The most common yttrium compound is yttrium oxide; insoluble compounds of yttrium are regarded as nontoxic, but water-soluble compounds are considered toxic. Yttrium has a hexagonal close-packed crystal structure.
Naturally occurring yttrium consists solely of yttrium-89, the element’s only stable isotope. Nineteen other radioactive isotopes exist, the least stable of which, yttrium-106, has a half-life of about 150 nanoseconds. The most stable of yttrium’s radioactive isotopes is yttrium-88, with a half-life of 106.63 days. Almost all of the remaining unstable yttrium isotopes have half-lives of less than one hour.
Unstable yttrium isotopes with mass numbers less than 89 (yttrium’s only stable isotope) undergo positron emission, a form of beta decay in which a proton is converted to a neutron, causing the isotope to release energy in the form of a positron and an electron neutrino. In yttrium, this process usually results in isotopes of strontium. Unstable yttrium isotopes with mass numbers greater than 89 undergo electron emission, another form of beta decay, in which a neutron is converted to a proton, resulting in the release of an electron and an electron neutrino. Yttrium isotopes that undergo this type of decay produce isotopes of zirconium.
Applications
Despite the name "rare earth element," such elements are usually quite abundant on Earth, occurring naturally in many different sources. Yttrium is not found freely in nature, but it is present in almost all rare earth minerals, including monazite and gadolinite. It is from monazite sand, which is made up of about 3 percent yttrium, that the element is most often extracted commercially via solvent extraction and ion exchange. In addition, the mineral xenotime, which is mined in Malaysia, consists of nearly 50 percent yttrium. Approximately six hundred metric tons of yttrium are mined annually. Yttrium is the fortieth most abundant element in Earth’s crust, with amounts measured at 33 parts per million. Samples of lunar soil brought back from the Apollo missions were tested and found to contain even higher amounts of yttrium—up to 213 parts per million. Yttrium serves no major biological role, but it can be toxic if inhaled, and long-term exposure can increase the risk of developing lung cancer. Yttrium that is dumped back into the environment amasses in soil, which leads to higher concentrations in both humans (typically in the liver) and animals.
Yttrium oxide has many uses and accounts for the majority of the element’s practical applications. Hundreds of thousands of pounds of yttrium oxide are used in conjunction with europium; together, the two create phosphors that make the red color in television tubes and LED televisions. Additionally, yttrium can be used as an alloy to refine the grain size and increase the strength of titanium, aluminum, and magnesium. The radioactive isotope yttrium-90 has various uses in the field of medicine. It is an ingredient in various drugs used to treat certain kinds of cancer, including leukemia and lymphoma, and is also used in the production of certain needles that display more cutting precision than typical medical scalpels. These needles have been used to cut pain-transmitting nerves in the spinal cord.
Bibliography
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Haynes, William M., ed. CRC Handbook of Chemistry and Physics. 95th ed. Boca Raton: CRC, 2014. Print.
Lucas, Jacques, et al. Rare Earths: Science, Technology, Production and Use. Waltham: Elsevier, 2015. Print.
"Technical Data for Yttrium." The Photographic Periodic Table of the Elements. Element Collection, n.d. Web. 11 Aug. 2015.
"Yttrium (Y)." Encyclopaedia Britannica. Encyclopaedia Britannica, 25 May 2014. Web. 11 Aug. 2015.