Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74. The name tungsten comes from the former Swedish name for the tungstate mineral scheelite, tung sten or "heavy stone". Tungsten is a rare metal found on Earth exclusively combined with other elements in chemical compounds rather than alone, it was identified as a new element in 1781 and first isolated as a metal in 1783. Its important ores include scheelite; the free element is remarkable for its robustness the fact that it has the highest melting point of all the elements discovered, melting at 3422 °C. It has the highest boiling point, at 5930 °C, its density is 19.25 times that of water, comparable with that of uranium and gold, much higher than that of lead. Polycrystalline tungsten is an intrinsically hard material, making it difficult to work. However, pure single-crystalline tungsten can be cut with a hard-steel hacksaw. Tungsten's many alloys have numerous applications, including incandescent light bulb filaments, X-ray tubes, electrodes in gas tungsten arc welding and radiation shielding.
Tungsten's hardness and high density give it military applications in penetrating projectiles. Tungsten compounds are often used as industrial catalysts. Tungsten is the only metal from the third transition series, known to occur in biomolecules that are found in a few species of bacteria and archaea, it is the heaviest element known to be essential to any living organism. However, tungsten interferes with molybdenum and copper metabolism and is somewhat toxic to more familiar forms of animal life. In its raw form, tungsten is a hard steel-grey metal, brittle and hard to work. If made pure, tungsten retains its hardness, becomes malleable enough that it can be worked easily, it is worked by drawing, or extruding. Tungsten objects are commonly formed by sintering. Of all metals in pure form, tungsten has the highest melting point, lowest vapor pressure, the highest tensile strength. Although carbon remains solid at higher temperatures than tungsten, carbon sublimes at atmospheric pressure instead of melting, so it has no melting point.
Tungsten has the lowest coefficient of thermal expansion of any pure metal. The low thermal expansion and high melting point and tensile strength of tungsten originate from strong covalent bonds formed between tungsten atoms by the 5d electrons. Alloying small quantities of tungsten with steel increases its toughness. Tungsten exists in two major crystalline forms: α and β; the former is the more stable form. The structure of the β phase is called A15 cubic. Contrary to the α phase which crystallizes in isometric grains, the β form exhibits a columnar habit; the α phase has one third of the electrical resistivity and a much lower superconducting transition temperature TC relative to the β phase: ca. 0.015 K vs. 1–4 K. The TC value can be raised by alloying tungsten with another metal; such tungsten alloys are sometimes used in low-temperature superconducting circuits. Occurring tungsten consists of four stable isotopes and one long-lived radioisotope, 180W. Theoretically, all five can decay into isotopes of element 72 by alpha emission, but only 180W has been observed to do so, with a half-life of ×1018 years.
The other occurring isotopes have not been observed to decay, constraining their half-lives to be at least 4 × 1021 years. Another 30 artificial radioisotopes of tungsten have been characterized, the most stable of which are 181W with a half-life of 121.2 days, 185W with a half-life of 75.1 days, 188W with a half-life of 69.4 days, 178W with a half-life of 21.6 days, 187W with a half-life of 23.72 h. All of the remaining radioactive isotopes have half-lives of less than 3 hours, most of these have half-lives below 8 minutes. Tungsten has 11 meta states, with the most stable being 179mW. Elemental tungsten resists attack by oxygen and alkalis; the most common formal oxidation state of tungsten is +6, but it exhibits all oxidation states from −2 to +6. Tungsten combines with oxygen to form the yellow tungstic oxide, WO3, which dissolves in aqueous alkaline solutions to form tungstate ions, WO2−4. Tungsten carbides are produced by heating powdered tungsten with carbon. W2C is resistant to chemical attack, although it reacts with chlorine to form tungsten hexachloride.
In aqueous solution, tungstate gives the heteropoly acids and polyoxometalate anions under neutral and acidic conditions. As tungstate is progressively treated with acid, it first yields the soluble, metastable "paratungstate A" anion, W7O6–24, which over time converts to the less soluble "paratungstate B" anion, H2W12O10–42. Further acidification produces the soluble metatungstate anion, H2W12O6–40, after which equilibrium is reached; the metatungstate ion exists as a symmetric cluster of twelve tungsten-oxygen octahedra known as the Keggin anion. Many other polyoxometalate anions exist as metastable species; the inclusion of a different atom such as phosphorus in place of the two central hydrogens in metatungstate produces a
St John of God Halswell is a service of the Health and Ability Services division of St John of God Hauora Trust. St John of God Hauora Trust is a New Zealand Registered Charitable Trust that provides health and social services to vulnerable people; the charity is a controlled entity of St John of God Health Care, one of the largest private Catholic providers of healthcare in Australasia. St John of God Halswell provides long-term residential support for people with physical and neurological disabilities in both a residential and community homes setting; the facility is located in the Christchurch suburb of Halswell. The facility is located in Nash Road in the Christchurch suburb of Halswell, close to the Aidanfield subdivision; the St John of God Chapel, a church registered as a Category I heritage building by the New Zealand Historic Places Trust, is part of the complex. St John of God Halswell has 60 beds; the Health and Ability Services division operates two community homes in Addington, two community homes in the Selwyn District and three studio apartments onsite.
The facility provides residential physical disability services for people 16 – 65 years of age, including those with long-term neurological and physical disabilities, such as multiple sclerosis, Huntington's disease, muscular dystrophy, cerebral palsy, spinal injury and brain injury. Where necessary, residents receive 24-hour nursing care and support provided by nurses and clinical and non-clinical teams. St John of God Halswell is situated in 20 acres of grounds, predominately laid in formal gardens. In February 2010, the St John of God Halswell gardens were awarded the Fowler Trophy from the Christchurch Horticultural Society and the Peter Lawrence Trophy from the Christchurch Beautifying Association. In February 2011, St John of God Halswell was awarded the Peter Skellercup Trophy in the Canterbury Horticultural Society “Summer Garden Awards” 2011. Official website
Sarah MacDonald is a Canadian-born organist and composer, living in the UK, holds the positions of Fellow and Director of Music at Selwyn College and Director of Ely Cathedral Girls' Choir. She has been at Selwyn since 1999, is the first woman to hold such a post in an Oxbridge Chapel. In 2018 Sarah was given the honorary award of Associate of the Royal School of Church Music. Sarah came to the United Kingdom from Canada in 1992 as Organ Scholar of Robinson College, Cambridge after studying piano and conducting at The Royal Conservatory of Music's Glenn Gould School in Toronto with Leon Fleisher, Marek Jablonski, John Tuttle. At Cambridge she read for a degree in Music, studied the organ with David Sanger, her early musical studies as a pianist took place at the Victoria Conservatory of Music on the west coast of British Columbia. Sarah has played numerous recitals and conducted choirs throughout the UK, North America, the Middle East, New Zealand, much of mainland Europe, she has made over 35 recordings, variously in the guises of pianist, organist and producer, works most with Regent Records.
Sarah is a winner of the Royal College of Organists' coveted Limpus Prize, has taught organ and conducting for Eton Choral Courses, Oundle for Organists, the Jennifer Bate Organ Academy, courses run by the RCO. For its first ten years, she was a regular director of the Girl Chorister Course at St Thomas' Church Fifth Avenue, in New York City, she is in demand as a guest conductor of international RSCM residential courses. Sarah holds the Royal College of Organists' Fellowship Diploma, is Examiner for the RCO and the Cambridge University Music Faculty, spent many years as a member of the Academic Board of the RCO and as a Trustee.. She is an Honorary Patron of the Herbert Howells Society. Sarah is active as a composer, has had works published by Encore Publications, the Royal School of Church Music, August Press and St James Music Press. Sarah writes a popular monthly column for the American Guild of Organists' magazine'The American Organist', called "UK Report". In January 2020, the'Sarah MacDonald Choral Series' with Selah Publishing was launched.
2019 - Regent Records: Christmas Music by Ben Parry 2019 - Regent Records: The garment of holiness, Choral Music by Iain Quinn 2018 - Regent Records: An Ely Christmas 2018 - Regent Records: Utrumne est ornatum, Choral Music by Mark Gotham 2017 - Regent Records: Marvellous Light, Choral Music by Ben Ponniah 2017 - Regent Records: Christmas from Selwyn 2016 - Regent Records: settings of the Magnificat and Nunc dimittis for upper voices 2016 - Regent Records: choral music by John Hosking 2015 - Regent Records: choral music for Advent and Christmas by Alan Bullard, including'O Come, Emmanuel' 2015 - Regent Records: "The Eternal Ecstasy" - including music by MacMillan, Tavener, Whitacre and Bullard 2014 - Regent Record: Choral music by Phillip Cooke 2013 - Regent Records: Wondrous Cross: liturgical choral music by Alan Bullard 2013 - Regent Records: Penitence and Redemption: Pergolesi Stabat Mater and other music for Lent and Passiontide 2011 - Regent Records: Choral Music by Gary Higginson 2010 - Regent Records: Milles Regretz: music for lutes and voices 2010 - Regent Records: God be in my head: Choral music by Paul Edwards 2009 - Regent Records: Come out, Lazar: the Shorter Choral works of Paul Spicer 2009 - Choir & Organ: A lover’s complaint: New music for choir and organ 2008 - Regent Records: A Candle to the Glorious Sun: Music by Martin Peerson & John Milton Senior 2008 - Regent Records: Sing reign of fair maid: Music for Christmas and the New Year 2007 - Priory Records: Master-Pieces from Selwyn College, Cambridge 2006 - Kevin Mayhew: Christus vincit: Music by Colin Mawby to celebrate his 70th birthday 2006 - Priory Records: Songs of Welcome: Music for Women’s Voices 2005 - URM Audio: The Moon of Wintertime: Carols from around the world 2004 - Priory Records: One day in thy courts: Settings of the Psalms 2003 - Priory Records: Complete New English Hymnal Vol. XIV 2000 - Herald AV Productions: Herbert Howells: Evening Canticles 2020 Several works in the'Sarah MacDonald Choral Series' 2020'Tomorrow shall be my dancing day', arrangement for ATB voices 2019'MacDonald in A flat', evening canticles for mixed voices 20