Holmium properties

Heat of vaporization, 66 see also Vaporization Helium, 91 boiling point, 63 heat of vaporization, 105 interaction between atoms, 277 ionization energy, 268 molar volume, 60 on Sun, 447 source, 91 Hematite, 404 Hemin, structure of, 397 Hess s Law, 111 Heterogeneous, 70 systems and reaction rate, 126 n-Hexane properties, 341 Hibernation, 2 Hildebrand, Joel H.. 163 Holmium, properties, 412 Homogeneous, 70 systems and reaction rate, 126 Hydration, 313 Hydrazine, 46, 47, 231 Hydrides of third-row elements, 102 boiling point of. 315 Hydrocarbons, 340 unsaturated, 342... 

Pure holmium has a metallic to bright silver luster. It is relatively soft and malleable, and is stable in dry air at room temperature, but rapidly oxidizes in moist air and at elevated temperatures. The metal has unusual magnetic properties. Few uses have yet been found for the element. The element, as with other rare earths, seems to have a low acute toxic rating. 

Silver-colored, ductile metal that is attacked slowly by air and water. The element exhibits interesting magnetic properties. Found in television tubes. Laser material such as YAG (yttrium-aluminum garnet) doped with holmium (as well as chromium and thulium) can be applied in medicine, especially in sensitive eye operations. 

Although stable at room temperatures, hohnium will corrode at higher temperatures and humidity. Its oxide coating is a yellowish film that reacts slowly with water and dissolves in weak acids. Holmium has one of the highest magnetic properties of any substance, but it has little commercial use. 

Einsteinium has homologous chemical and physical properties of the rare-earth holmium (g Ho), located just above it in the lanthanide series in the periodic table. 

Currently, holmium metal does not have much commercial application. However, because of its unusual magnetic properties, it is being used in research studies to explore the magnetic and alloying behavior of metals. 

A consequence of the lanthanide contraction is that when holmium is reached, the increase in size from n = 5 — n = 6 has been lost and Ho34- is the same size as the much lighter Y1+ (104 pm) with correspondingly similar properties.44 The contraction docs not proceed sufficiently far to include Sc3+ (88 pm), but its properties may be extrapolated from the lanthanide series, and in some ways it provides a bridge between the strictly lanthanide metals and the transition metals... 

Lanthanide elements (referred to as Ln) have atomic numbers that range from 57 to 71. They are lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). With the inclusion of scandium (Sc) and yttrium (Y), which are in the same subgroup, this total of 17 elements are referred to as the rare earth elements (RE). They are similar in some aspects but very different in many others. Based on the electronic configuration of the rare earth elements, in this chapter we will discuss the lanthanide contraction phenomenon and the consequential effects on the chemical and physical properties of these elements. The coordination chemistry of lanthanide complexes containing small inorganic ligands is also briefly introduced here [1-5]. 

Element 39, with 4d 5s2 electron configuration, is also similar to the lanthanides. It occurs with the lanthanides in minerals the best source is xenotime, YPO4. Yttrium has properties approximately midway between those of Sc and La its compounds also resemble those of the heavy earths dysprosium and holmium, the ionic radius (0.90 A) being similar. 

Another potential use for holmium is a result of its very unusual and strong magnetic properties. It has been used in alloys with other metals to produce some of the strongest magnetic fields ever produced. Holmium also has some limited use in the manufacture of control rods for nuclear power plants. Control rods limit the number of neutrons available to cause the fission of uranium in nuclear reactors, thus controlling the amount of energy produced in the plant. 

The name is from the Latin Holmia for the city of Stockholm, the region where the original minerals were found. The discovery of holmium was part of the complex yttria rare-earths research. A new element was suggested by Jacques-Louis Soret (1827-1890) in 1878 and was named by Per Theodor Cleve (1840-1905) in 1880 its oxide was isolated in 1886 by Lecoq de Boisbaudran. The pure metal was isolated in 1911 by 0. Holmberg. It is a rare element and does not occur in pure form in nature. The silvery metal has unusual magnetic properties but no current commercial uses. 

It is generally held that metal oxide perovskites with extrinsic oxygen vacancies react with atmospheric water. This entrains hydrogen into the lattice and leads to their significant proton conducting properties. The location of these hydrogen atoms was studied as a function of a series of dopants in a cerium based ceramic. The dopants were niobium, holmium... 

Cleve studied the group of elements known as the lanthanide elements. In 1879 he discovered two new lanthanide elements holmium and thufinm. The following year he undertook a thorough investigation of the newly discovered element scandium and proved that it had the properties predicted... 

The lanthanide or rare earth elements (atomic numbers 57 through 71) typically add electrons to the 4f orbitals as the atomic number increases, but lanthanum (4f°) is usually considered a lanthanide. Scandium and yttrium are also chemically similar to lanthanides. Lanthanide chemistry is typically that of + 3 cations, and as the atomic number increases, there is a decrease in radius for each lanthanide, known as the lanthanide contraction. Because bonding within the lanthanide series is usually predominantly ionic, the lanthanide contraction often determines the differences in properties of lanthanide compounds and ions. Lanthanide compounds often have high coordination numbers between 6 and 12. see also Cerium Dysprosium Erbium Europium Gadolinium Holmium Lanthanum Lutetium Praseodymium Promethium Samarium Terbium Thulium Ytterbium. 

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