94 | The History and Use of Our Earth’s Chemical Elements AbundanceandSource
94 | The History and Use of Our Earth’s Chemical Elements AbundanceandSource
Vanadium is not found in its pure state. Small amounts of vanadium can be found in phosphate rocks and some iron ores. Most of it is recovered from two minerals: vanadinite, which is a compound of lead and chlorine plus some vanadium oxide, and carnotite, a min- eral containing uranium, potassium, and an oxide of vanadium. Because of its four oxidation states and its ability to act as both a metal and a nonmetal, vanadium is known to chemically combine with over 55 different elements.
Vanadium’s principal ores are roscoelite, patronite, vanadinite, and carnotite, which are found in the states of Idaho, Montana, Arkansas, and Arizona as well as in Mexico and Peru. It is also a by-product from the production of phosphate ores.
History Two unrelated discoveries of vanadium seem to have occurred. When he was experiment-
ing with iron in 1830, Nils Gabriel Sefstrom (1787–1845), a Swedish chemist and mineralo- gist, identified a small amount of a new metal. Because vanadium compounds have beautiful colors, he named this new metal after Vanadis, the mythological goddess of youth and beauty in his native country, Scandinavia.
Earlier, in 1801 in Mexico, Andres Manuel del Rio, a chemist and mineralogist, discovered an unusual substance he called erythronium, but he was told it was similar to chromium. Only later was it found to be vanadium. Some early references credit Del Rio with vanadium’s discovery, but the most recent references list Sefstrom as the discoverer.
Sometime later in 1869, vanadium metal was isolated from its ores by Henry Enfield Roscoe (1833–1915), but Sefstrom had already received credit for the discovery of the ele- ment vanadium.
CommonUses The major use of vanadium is as an alloying metal to make a strong and corrosion-resis-
tant form of steel that is well suited for structures such as nuclear reactors. It does not absorb neutrons or become “stretched” by heat and stress, as does normal stainless steel, thus making vanadium ideal for the construction of nuclear reactors.
Some of its compounds, particularly the oxides, are used in chemical industries as catalysts
to speed up organic chemical reactions. The yellow-brown vanadium pentoxide (V 2 O 5 ) is used as a catalyst to facilitate the production of sulfuric acid by the contact process. Vanadium pent- oxide is also used as a photographic developer, to dye textiles, and in the production of artificial rubber. When combined with glass, it acts as a filter against ultraviolet rays from sunlight.
ExamplesofCompounds The ions of vanadium are V 2+ , V 3+ , V 4+ , and V 5+ , and they enable the formation of
four different oxides of vanadium: vanadium(II) oxide (VO), vanadium(III) oxide (V 2 O 3 ), vanadium(IV) oxide (VO 2 ), and vanadium(V) oxide or vanadium pentoxide (V 2 O 5 ). The same sequence of four vanadium ions can combine with chlorine and fluorine to form related compounds. Vanadium carbide (VC) is used to alloy iron to produce high-speed, high-temperature cut- ting tools for cutting metals and other hard substances.
Guide to the Elements | 95 Vanadium sulfate (VOSO 4 ) acts as a catalyst as well as a reducing agent. It is used to color
glass and ceramics and as a mordant (fixing dyes to textiles). Vanadium pentoxide (V 2 O 5 ) is a reddish-yellow powder extracted from minerals using strong acids or alkalies. In addition to being used as a catalyst for many organic chemical reactions, it is used in photography and in UV-protected windowpanes and to color ceramics and dye cloth.
Hazards Vanadium powder, dust, and most of its oxide compounds are explosive when exposed
to heat and air. They are also toxic when inhaled. Vanadium chloride compounds are strong irritants to the skin and poisonous when ingested.
Many of its compounds must be stored in a dry, oxygen-free atmosphere or in containers of inert gas. Protective clothing and goggles should be worn when handling vanadium, as well as with most of the other transition elements.
CHROMIUM SYMBOL:Cr PERIOD:4 GROUP:6(VIB) ATOMICNO:24
ATOMICMASS:51.996amu VALENCE:2,3,and6 OXIDATIONSTATE:+2,+3,and +6 NATURALSTATE:Solid ORIGINOFNAME:FromtheGreekwordchromaorchromos,meaning“color,”becauseof themanycolorsofitsmineralsandcompounds. ISOTOPES:Thereare26isotopesoftheelementchromium;fourarestableandfound innature,andtherestareartificiallyproducedwithhalf-livesfromafewmicroseconds toafewdays.Thefourstableisotopesandtheirpercentageofcontributiontothe
totalamountofchromiumonEarthareasfollows: 50 Cr=4.345%, 52 Cr=83.789%, 53 Cr=9.501%,and 54 Cr=2.365%.Cr-50isradioactivebuthassuchalonghalf-
life—1.8×10 +17 years—thatitisconsideredtocontributeabout4%tothetotalamountof chromiumfoundonEarth.
ELECTRONCONFIGURATION EnergyLevels/Shells/Electrons Orbitals/Electrons
s2,p6
3-M=13
s2,p6,d5