Scandium subgroup

Sc. The existence of scandium was predicted by D. I. Mendeleev. He called this element ekaboron with the atomic mass between 40 and 48 in 1869. In 1879 Lars Fredrik Nilson found a new element in the minerals euxenite and gadolinite from Scandinavia. He named it scandium, from the Latin Scandia meaning "Scandinavia".

Y. In 1787, Carl Axel Arrhenius found a new mineral near Ytterby in Sweden and named it ytterbite, after the village. Johan Gadolin found yttrium's oxide in Arrhenius' sample in 1789 and the element yttrium was first recognised in 1794 by J. Gadolin.

La. It was discovered in 1839 by the Swedish scientist Carl Gustav Mosander after many years of investigation of cerium mineral that had been previously individual substance. Lanthanum was isolated in a relatively pure form in 1923.

Ac. French chemist André-Louis Debierne discovered actinium in 1899 1894. The word actinium comes from the Greek aktis, aktinos, meaning beam or rays, and derived from its radioactivity.

Titanium Subgroup

Ti. (pronounced tai’teniəm) The Englishman, mineralogist-amateur and pastor W. Gregor discovered titanium in 1791. High purity titanium was obtained by A. Moissian in 1895.

Zr. М. Кlaproth discovered this element in 1789 in mineral zircon.

Hf. (pronounced ’hæfniəm) Dirk Coster and Georg von Hevesy discovered hafnium in zirconium ores by the spectroscopical method in 1923. It was the missing element filled the gap in the Periodic table and validated the original 1869 prediction of D. Mendeleyev.

Ku (Rf). This radioactive element was discovered by the Soviet physicist G. Flerov and his co-workers in 1964 (Dubna, USSR):

²⁴²₉₄Pu +²²₁₀Ne = ²⁶⁰₁₀₄Кu + 4¹₀n;

The halfdecay period of the most stable isotope ²⁶⁰₁₀₄Кu is 0.3 sec. The Soviet scientists proposed the name Kurchatovium for the new element. The Americans proposed the name Rutherfordium for the new element.

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. Thortveitite can 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