Holmium 166

Holmium has almost no commercial applications, although it has unusual magnetic properties, which are used in the pole pieces of superconducting research magnets (Tallahassee, Florida). One variant of the YAG laser material is also holmium doped. 

Q Cermet is a composite material, co-sintered with a ceramic (an oxide) and a metol powder. 

Erbium has a limited use. It is, however, possible to exploit the fact that, like many lanthanides, the element has specific light absorption characteristics. Erbium oxide, itself rose pink, colors glass and glazing. This glass absorbs infrared radiation. 

SYMBOL Ho PERIOD 6 SERIES NAME Lanthanide ATOMIC NO 67 

ATOMIC MASS 164.903 amu VALENCE 3 OXIDATION STATE -t-3 NATURAL STATE  

ORIGIN OF NAME Derived from the Latin word for the ancient city named Holmia (present-day Stockholm, located in Sweden). 

ISOTOPES There are a total of 57 isotopes of holmium. Only one of these, Ho-165, is stable, and it is the only isotope found in the Earth s crust. All the other 56 isotopes have half-lives of a few milliseconds to 1.20x10+ years, the half-life of Ho-166. 

Holmium is a crystal-like, solid rare-earth with a metaUic luster. It is one of the more scarce elements of the lanthanide series. It is soft, hke lead, and can be hammered and pounded into thin sheets. 

Hodgkin s third major project was determining the structure of the protein insulin. It was only technical advances in the 1960s that made the solution finally possible. When the results were published in 1969, the researchers were listed in alphabetical order, showing her willingness to share credit and her egalitarian attitude toward all research workers. 

Marelene Rayner-Canham Geoffrey W. Rayner-Canham 

Farago, Peter (1977). Interview with Dorothy Crowfoot Hodgkin. Journal of Chemical Education 54(4) 214—216. 

Georgina (1998). Dorothy Hodgkin A Life. London Granta Publications. 

McGrayne, Sharon Bertsch (1993). Nobel Prize Women in Science Their Lives, Struggles and Momentous Discoveries. New York Birch Lane Press. 

Data reported for the solubility constant of Ho(OH)3(s) are listed in Table 8.43. The accepted data relate only to a temperature of 25 °C and at zero ionic strength. N o data at fixe d ionic strength are ret aine d by this review. The average of the values listed in Table 8.39 is selected as the solubility constant for Ho(OH)3(s) at zero ionic strength. 

Data reported for the stability constant of HoOH are listed in Table 8.44. The data only cover a relatively small temperature range (25-55°C), the majority of which come from the study of Klungness and Byrne (2000). This latter study obtained data at 0.7 moll NaClO from 25 to 55 °C and also at 25 °C from 0.1 to 5.5 moll using NaClO as the medium. The only other accepted datum on the stability of HoOH comes from the work of Frolova, Kumok and Serebrennikov (1966) who determined a stability constant at 25 °C and in 0.3 moll NaClO. All of these data are retained in the present review. 

There are only two literature sources that list data for the stabihty of the higher monomeric stability constants of holmium (Fatin-Rouge and BiinzU, 1999 Step-anchikova and Biteikina, 2006), where the former study proposed values for the stability of Ho(OH)g(aq) in two media at 0.1 moll and the latter for the three species Ho(OH)2 to Ho(OH)4 at zero ionic strength. These data are not considered consistent with the stability constant selected for HoOH in this review. For the data of Fatin-Rouge and Biinzli (1999), the stability constant given for log 0 indicates that it is greater than 3-log 4. As indicated previously, this behaviour 

T(°C) / (reported) Medium / (mol kg ) trix (molkg-M log / , (reported) log (accepted) References 

25 0 — Data at fixed ionic strength 0 -7.85 Chirkst, Lobacheva and Dzhevaga (2011) 

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L. Holmia, for Stockholm). The special absorption bands of holmium were noticed in 1878 by the Swiss chemists Delafontaine and Soret, who announced the existence of an "Element X." Cleve, of Sweden, later independently discovered the element while working on erbia earth. The element is named after cleve s native city. Holmia, the yellow oxide, was prepared by Homberg in 1911. Holmium occurs in gadolinite, monazite, and in other rare-earth minerals. It is commercially obtained from monazite, occurring in that mineral to the extent of about 0.05%. It has been isolated by the reduction of its anhydrous chloride or fluoride with calcium metal. 

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. 

Parameter Gadolinium Terbium Dysprosium Holmium Erbium ThuUmn Ytterbium Lutetium... 

Some nut trees accumulate mineral elements. Hickory nut is notable as an accumulator of aluminum compounds (30) the ash of its leaves contains up to 37.5% of AI2O2, compared with only 0.032% of aluminum oxide in the ash of the Fnglish walnut s autumn leaves. As an accumulator of rare-earth elements, hickory greatly exceeds all other plants their leaves show up to 2296 ppm of rare earths (scandium, yttrium, lanthanum, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium). The amounts of rare-earth elements found in parts of the hickory nut are kernels, at 5 ppm shells, at 7 ppm and shucks, at 17 ppm. The kernel of the Bra2d nut contains large amounts of barium in an insoluble form when the nut is eaten, barium dissolves in the hydrochloric acid of the stomach. 

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... 

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