Студопедия
Случайная страница | ТОМ-1 | ТОМ-2 | ТОМ-3
АрхитектураБиологияГеографияДругоеИностранные языки
ИнформатикаИсторияКультураЛитератураМатематика
МедицинаМеханикаОбразованиеОхрана трудаПедагогика
ПолитикаПравоПрограммированиеПсихологияРелигия
СоциологияСпортСтроительствоФизикаФилософия
ФинансыХимияЭкологияЭкономикаЭлектроника

Vanadium Subgroup. V.(pronounced /və’neIdiəm/) Vanadium was originally discovered by Andrés Manuel del Río

Vanadium Subgroup | Compounds | Titanium subgroup elements, IVB | Hydroxides Е(ОН)4 are compounds of nonstoichiometric composition ЕО2.nH2O. Ortho-titanic (a-titanic) H4TiO4 (Ti(OH)4), and more inert meta-titanic(b-titanic) H2TiO3 are known. | Chemical properties of titanium |


Читайте также:
  1. Copper subgroup trends
  2. Scandium and Titanium Subgroups
  3. Scandium subgroup
  4. Titanium subgroup elements, IVB
  5. Vanadium Subgroup

V. (pronounced /və’neIdiəm/) Vanadium was originally discovered by Andrés Manuel del Río, a Spanish-born Mexican mineralogist, in 1801, and it was rediscovered in 1831 (N. Sefstrom, Sweeden).

Nb. (pronounced /nai’əubiəm/) (Greek mythology: Niobe, daughter of Tantalus). The English chemist Charles Hatchett reported a new element similar to tantalum in 1801, and named it columbium.

Ta. (pronounced /tæntələm/). Tantalum was discovered in Sweden in 1802 by Anders Ekeberg.

Occurrence

Scandium is found in abundance in the earth's crust that is comparable to the abundance of cobalt. However, scandium is distributed sparsely and occurs in trace amounts in many minerals. Rare minerals thortveitite (Sc,Y)2Si2O7, euxenite, are the only known concentrated sources of this element. Thortveititecan contain up to 45%, as scandium(III) oxide. Scandium is more common in the sun and certain stars than on the Earth.

Yttrium is almost always found combined with the lanthanoids in rare earth minerals and is never found in nature as a free element.

 

  Sc Y La Ac
Content in the Earth crust, %(mol.) 2×10-4 5×10-4 2×10-4 5×10-15
Common minerals thortveitite gadolinite thortveitite    

 

As shown in Table below, titanium is very abundant (its content in the earth crust is larger than that of carbon), Zr and Hf are relatively rare. These elements are encountered only as compounds in nature.

The main minerals are primarily polymorphs of TiO2 (rutile, anatase, brookite etc.), ilmenite (FeTiO3), perovskite (CaTiO3), as well in many iron ores. Significant titanium-bearing ilmenite deposits exist in Ukraine and also in Australia, Canada, China etc.

Zr and Hf are disseminated elements. The most important minerals of Zr are zircon ZrSiO4 and baddeleyite ZrO2. Hafnium is always admixture to zirconium minerals (from 0.5 to 5.5% concerning Zr) and doesn’t form its own minerals.

 

  Ti Zr Hf
Content in the Earth crust, %(mol.) 0.63 1.7×10-2 3.2×10-4
Common minerals Perovskite, rutile, anatase, ilmenite etc. Zircon, baddeleyite -

 

Despite the fact that all these elements are quite abundant and many minerals containing them are known their own mines don’t exist. These elements are dispersed (disseminated) and mostly are admixtures of various ores containng Fe, Ti, or Pb. The minerals of large importance are natronite V2S5, vanadite 3Pb3(VO4)2.PbCl2, columbite Fe(NbO3)2, tantallite Fe(TaO3)2. Niobium has physical and chemical properties similar to those of the element tantalum, and the two are therefore difficult to distinguish.

 

  V Nb Ta
Content in the Earth crust, %(mol.) 0.015 1.0×10-3 2.0×10-4
Common minerals natronite, vanadite columbite Tantalite

Дата добавления: 2015-07-25; просмотров: 61 | Нарушение авторских прав

<== предыдущая страница | следующая страница ==>
Scandium subgroup| Scandium and Titanium Subgroups
mybiblioteka.su - 2015-2024 год. (0.008 сек.)