Tantalum is a chemical element; it has symbol Ta and atomic number 73. Previously known as tantalium, it is named after Tantalus, a figure in Greek mythology. Tantalum is a very hard, ductile, lustrous, blue-gray transition metal that is highly corrosion-resistant. It is part of the refractory metals group, which are widely used as components of strong high-melting-point alloys. It is a group 5 element, along with vanadium and niobium, and it always occurs in geologic sources together with the chemically similar niobium, mainly in the mineral groups tantalite, columbite and coltan.
Group 5 is a group of elements in the periodic table. Group 5 contains vanadium (V), niobium (Nb), tantalum (Ta) and dubnium (Db). This group lies in the d-block of the periodic table. This group is sometimes called the vanadium group or vanadium family after its lightest member; however, the group itself has not acquired a trivial name because it belongs to the broader grouping of the transition metals.
Antimony pentafluoride is the inorganic compound with the formula SbF5. This colourless, viscous liquid is a strong Lewis acid and a component of the superacid fluoroantimonic acid, formed upon mixing liquid HF with liquid SbF5 in 1:1 ratio. It is notable for its strong Lewis acidity and the ability to react with almost all known compounds.
Hydrogen fluoride (fluorane) is an inorganic compound with chemical formula HF. It is a very poisonous, colorless gas or liquid that dissolves in water to yield an aqueous solution termed hydrofluoric acid. It is the principal industrial source of fluorine, often in the form of hydrofluoric acid, and is an important feedstock in the preparation of many important compounds including pharmaceuticals and polymers, e.g. polytetrafluoroethylene (PTFE). HF is also widely used in the petrochemical industry as a component of superacids. Due to strong and extensive hydrogen bonding, it boils at near room temperature, much higher than other hydrogen halides.
Tantalum pentoxide, also known as tantalum(V) oxide, is the inorganic compound with the formula Ta
2O
5. It is a white solid that is insoluble in all solvents but is attacked by strong bases and hydrofluoric acid. Ta
2O
5 is an inert material with a high refractive index and low absorption, which makes it useful for coatings. It is also extensively used in the production of capacitors, due to its high dielectric constant.
Selenium tetrafluoride (SeF4) is an inorganic compound. It is a colourless liquid that reacts readily with water. It can be used as a fluorinating reagent in organic syntheses (fluorination of alcohols, carboxylic acids or carbonyl compounds) and has advantages over sulfur tetrafluoride in that milder conditions can be employed and it is a liquid rather than a gas.
Tungsten oxytetrafluoride is an inorganic compound with the formula WOF4. It is a colorless diamagnetic solid. The compound is one of many oxides of tungsten. It is usually encountered as product of the partial hydrolysis of tungsten hexafluoride.
Tantalum(V) bromide is the inorganic compound with the formula Ta2Br10. Its name comes from the compound's empirical formula, TaBr5. It is a diamagnetic, orange solid that hydrolyses readily. The compound adopts an edge-shared bioctahedral structure, which means that two TaBr5 units are joined by a pair of bromide bridges. There is no bond between the Ta centres. Niobium(V) chloride, niobium(V) bromide, niobium(V) iodide, tantalum(V) chloride, and tantalum(V) iodide all share this structural motif.
The dioxygenyl(or dioxyl) ion, O+
2, is a rarely-encountered oxycation in which both oxygen atoms have a formal oxidation state of +1/2. It is formally derived from oxygen by the removal of an electron:
Niobium pentoxide is the inorganic compound with the formula Nb2O5. A colorless, insoluble, and fairly unreactive solid, it is the most widespread precursor for other compounds and materials containing niobium. It is predominantly used in alloying, with other specialized applications in capacitors, optical glasses, and the production of lithium niobate.
Niobium(V) fluoride, also known as niobium pentafluoride, is the inorganic compound with the formula NbF5. It is a colorless solid.
Potassium heptafluorotantalate is an inorganic compound with the formula K2[TaF7]. It is the potassium salt of the heptafluorotantalate anion [TaF7]2−. This white, water-soluble solid is an intermediate in the purification of tantalum from its ores and is the precursor to the metal.
Vanadium(V) fluoride is the inorganic compound with the chemical formula VF5. It is a colorless volatile liquid that freezes near room temperature. It is a highly reactive compound, as indicated by its ability to fluorinate organic substances.
In chemistry, the square antiprismatic molecular geometry describes the shape of compounds where eight atoms, groups of atoms, or ligands are arranged around a central atom, defining the vertices of a square antiprism. This shape has D4d symmetry and is one of the three common shapes for octacoordinate transition metal complexes, along with the dodecahedron and the bicapped trigonal prism.
Polyhalogen ions are a group of polyatomic cations and anions containing halogens only. The ions can be classified into two classes, isopolyhalogen ions which contain one type of halogen only, and heteropolyhalogen ions with more than one type of halogen.
Hafnium tetrafluoride is the inorganic compound with the formula HfF4. It is a white solid. It adopts the same structure as zirconium tetrafluoride, with 8-coordinate Hf(IV) centers.
Tantalum(V) iodide is the inorganic compound with the formula Ta2I10. Its name comes from the compound's empirical formula, TaI5. It is a diamagnetic, black solid that hydrolyses readily. The compound adopts an edge-shared bioctahedral structure, which means that two TaI5 units are joined by a pair of iodide bridges. There is no bond between the Ta centres. Niobium(V) chloride, niobium(V) bromide, niobium(V) iodide, tantalum(V) chloride, and tantalum(V) bromide all share this structural motif.
Organotantalum chemistry is the chemistry of chemical compounds containing a carbon-to-tantalum chemical bond. A wide variety of compound have been reported, initially with cyclopentadienyl and CO ligands. Oxidation states vary from Ta(V) to Ta(-I).
Rhodium pentafluoride is an inorganic compound with the formula Rh4F20. It is a red solid. It is prepared by fluorination of rhodium trifluoride at 400 °C.
Protactinium compounds are compounds containing the element protactinium. These compounds usually have protactinium in the +5 oxidation state, although these compounds can also exist in the +2, +3 and +4 oxidation states.
