Technetium (43)

Since its discovery, searches for the element technetium [TEK-NET-EE-UM] in terrestrial materials have been made without success. Technetium has been found in the spectrum of S-, M-, and N-type stars, and its presence in stellar matter is leading to new theories of the production of heavy elements in the stars.

Technetium is a silvery-grey metal that tarnishes slowly in moist air. Until 1960, technetium was available only in small amounts. The chemistry of technetium is related to that of rhenium.

•Name: Technetium
•Symbol: Tc
•Atomic number: 43
•Atomic weight: [ 98 ]
•Standard state: solid at 298 K
•CAS Registry ID: 7440-26-8
•Group in periodic table: 7
•Period in periodic table: 5
•Block in periodic table: d-block
•Color: silvery grey metallic
•Classification: Metallic

Historical information

Technetium was discovered by Carlo Perrier, Emilio Segre at 1937 in Italy. Origin of name is from the Greek word "technikos" meaning "artificial". Element 43 (technetium) was predicted on the basis of the periodic table by Mendeleev. He suggested that it should be very similar to manganese and gave it the name ekamanganese. Technetium was erroneously reported as having been discovered in 1925, at which time it was named masurium. The element was actually discovered by C. Perrier and Emilio Gino Segre in Italy in 1937. It was found in a sample of molybdenum bombarded by deuterons. Technetium was the first element to be produced artificially and all its isotopes are radioactive. It is named after the Greek technetos, artificial.

Physical properties

•Melting point: 2430 [or 2157 °C (3915 °F)] K
•Boiling point: 4538 [or 4265 °C (7709 °F)] K
•Density of solid: 11500 kg m-3

Orbital properties

•Ground state electron configuration: [Kr].4d6.5s1
•Shell structure: 2.8.18.14.1
•Term symbol: 6S5/2

Isolation

It is never necessary to make a sample of technetium anywhere other than specialist laboratories. This is because technetium is radioactive. Technetium is a byproduct of the nuclear industry and is a product of uranium decay. Alternatively it can be made by the bombardment of molydenum targets with deuterium nuclei.

Because of the scale of the nuclear industry it is possible to make quite large quantities of technetium (kilograms). The metal itself may be made by the reaction of the sulfide Tc2S7 with hydrogen at 1100°C or of the pertechnate NH4TcO4 with hydrogen.

Molybdenum (42)

Molybdenum (MO-LIB-DEN-UM) is a silvery-white, hard, transition metal. Scheele discovered it in 1778. It was often confused with graphite and lead ore. Molybdenum is used in alloys, electrodes and catalysts. The World War 2 German artillery piece called "Big Bertha" contains molybdenum as an essential component of its steel.

•Name: Molybdenum
•Symbol: Mo
•Atomic number: 42
•Atomic weight: 95.96
•Standard state: solid at 298 K
•CAS Registry ID: 7439-98-7
•Group in periodic table: 6
•Period in periodic table: 5
•Block in periodic table: d-block
•Color: grey metallic
•Classification: Metallic

Historical information

Molybdenum was discovered by Carl William Scheele at 1781 in Sweden. Origin of name is from the Greek word "molybdos" meaning "lead". In 1778 Carl Welhelm Scheele conducted research on an ore now known as molybdenite. He concluded that it did not contain lead as was suspected at the time and reported that the mineral contained a new element that he called molybdenum after the mineral. Molybdenum metal was prepared in an impure form in 1782 by Peter Jacob Hjelm.

Physical properties

•Melting point: 2896 [or 2623 °C (4753 °F)] K
•Boiling point: 4912 [or 4639 °C (8382 °F)] K
•Density of solid: 10280 kg m-3

Orbital properties

•Ground state electron configuration: [Kr].4d5.5s1
•Shell structure: 2.8.18.13.1
•Term symbol: 7S3

Isolation

It is not normally necessary to make samples of molybdenum metal in the laboratory since it is readily available commercially. Industrially, its extraction is sometimes linked to copper production. The normal process is for the sulfide MoS2 to be "roasted" to form the oxide MoO3. This is often used directly in the steel industry.

Pure samples of the metal are available by first dissolving the oxide in ammonium hydroxide to make ammonium molybdate, (NH4)2[MO4], and then reduction of the molybdate with hydrogen gas to form the metal.

Niobium (41)

The name niobium was adopted officially by IUPAC in 1950, but a few commercial producers still like to refer to it as columbium. Niobium is a shiny, white, soft, and ductile metal, and takes on a bluish tinge when exposed to air at room temperatures for a long time. The metal starts to oxidize in air at high temperatures, and when handled hot must be done so under a protective atmosphere so as to minimize oxide production.

•Name: Niobium
•Symbol: Nb
•Atomic number: 41
•Atomic weight: 92.90638 (2)
•Standard state: solid at 298 K
•CAS Registry ID: 7440-03-1
•Group in periodic table: 5
•Period in periodic table: 5
•Block in periodic table: d-block
•Color: grey metallic
•Classification: Metallic

Historical information

Niobium was discovered by Charles Hatchett at 1801 in England. Origin of name: from the Greek word "Niobe" meaning "daughter of Tantalus" (tantalum is closely related to niobium in the periodic table). Niobium was discovered in 1801 by Charles Hatchett in an ore called columbite sent to England in the 1750s by John Winthrop the Younger, the first governor of Connecticut, USA. Hatchett called the new element columbium. He was not able to isolate the free element. There was then considerable confusion concerning the distinction between niobium and tantalum as they are so closely related. This confusion was resolved by Heinrich Rose, who named niobium, and Marignac in 1846. The name niobium is now used in place of the original name "columbium".

The metal niobium was first prepared in 1864 by Blomstrand, who reduced the chloride by heating it in a hydrogen atmosphere.

Physical properties

•Melting point: 2750 [or 2477 °C (4491 °F)] K
•Boiling point: 5017 [or 4744 °C (8571 °F)] K
•Density of solid: 8570 kg m-3

Orbital properties

•Ground state electron configuration: [Kr].4d4.5s1
•Shell structure: 2.8.18.12.1
•Term symbol: 6D1/2

 

Isolation

Isolation of niobium appears to be complicated. Niobium minerals usually contain both niobium and tantalum. Since they are so similar chemically, it is difficult to separate them. Niobium can be extracted from the ores by first fusing the ore with alkali, and then extracting the resultant mixture into hydrofluoric acid, HF. Current methodology involves the separation of tantalum from these acid solutions using a liquid-liquid extraction technique. In this process tantalum salts are extracted into the ketone MIBK (methyl isobutyl ketone, 4-methyl pentan-2-one). The niobium remains in the HF solution. Acidification of the HF solution followed by further extraction in MIBK gives an organic solution containing niobium.

Zirconium (40)

Zirconium is a greyish-white lustrous metal. The finely divided metal can ignite spontaneously in air, especially at elevated temperatures. The solid metal is much more difficult to ignite. The inherent toxicity of zirconium compounds is low. Hafnium is invariably found in zirconium ores, and the separation is difficult. Commercial grade zirconium contains from 1 to 3% hafnium. The hafnium is removed from the zirconium used in the nuclear power industry.

Zirconium is found in S-type stars, and has been identified in the sun and meteorites. Analyses of lunar rock samples show a surprisingly high zirconium oxide content as compared with terrestrial rocks. Some forms of zircon (ZrSiO4) have excellent gemstone qualities.

•Name: Zirconium
•Symbol: Zr
•Atomic number: 40
•Atomic weight: 91.224 (2)
•Standard state: solid at 298 K
•CAS Registry ID: 7440-67-7
•Group in periodic table: 4
•Period in periodic table: 5
•Block in periodic table: d-block
•Color: silvery white
•Classification: Metallic

Historical information
Zirconium was discovered, in its impure form, by Martin Heinrich Klaproth at 1789 in Berlin, Germany. Origin of name is from the Arabic word "zargun" meaning "gold color," which describes the color of the gemstone now known as zircon (ZrSiO4). The minerals jargon, hyacinth, and jacinth also contain zircon and these have been known since biblical times and are mentioned in the bible in several places. The existence of a new element within these minerals was not suspected until studies by Martin Heinrich Klaproth in the late 18th century.

The impure metal was first isolated by Jöns Jacob Berzelius in 1824 who heated a mixture of potassium and potassium zirconium fluoride together in an iron tube. Pure zirconium was first prepared in 1914.

Physical properties
•Melting point: 2128 [or 1855 °C (3371 °F)] K
•Boiling point: 4682 [or 4409 °C (7968 °F)] K
•Density of solid: 6511 kg m-3

Orbital properties
•Ground state electron configuration: [Kr].4d2.5s2
•Shell structure: 2.8.18.10.2
•Term symbol: 3F2

Isolation
Zirconium is available from commercial sources so preparation in the laboratory is not normally required. In industry, reduction of ores with carbon is not a useful option as intractable carbides are produced. As for titanium, the Kroll method is used for zirconium and involves the action of chlorine and carbon upon baddeleyite (ZrO2). The resultant zirconium tetrachloride, ZrCl4, is separated from the iron trichloride, FeCl3, by fractional distillation. Finally ZrCl4 is reduced to metallic zirconium by reduction with magnesium (Mg). Air is excluded so as to prevent contamination of the product with oxygen or nitrogen.

ZrO2 + 2Cl2 + 2C (900°C) → ZrCl4 + 2CO

ZrCl4 + 2Mg (1100°C) → 2MgCl2 + Zr

Excess magnesium and magnesium dichloride is removed from the product by treatment with water and hydrochloric acid to leave a zirconium "sponge". This can be melted under helium by electrical heating.

FUN FACTS!
•Australia, Brazil, India, Russia and the USA are the major locations where zirconium deposits are found.
•It is abundant in S-type stars and its existence has also been detected in the Sun and the meteorites.
•The abundance of this metal in lunar rock samples has been found to be higher than what is found in terrestrial rocks.
•As a transition metal, zirconium is a good conductor of heat and fire. It also scores well on malleability and ductility.
•The metal has an atomic radius (pm) of 160 and Ionic radius of 790(+4e).
•Its lattice structure is hexagonal, and it has a lattice constant of 3.230.
•Specific heat is 0.281 @20°C J/g mol, and fusion heat is 19.2 (kJ/mol).
•Zirconium in powder form is highly susceptible to combustion, however, far less when in solid form.
•Alkalis, acids, salt water and many other agents have no corrosive effects on zirconium. However, if combined with hydrochloric and sulfuric acid, it will dissolve. This reaction becomes faster in the presence of fluorine.
•Inhalation of the compounds of this metal may cause skin and lung granulomas (a tumor composed of granulation tissue resulting from injury or inflammation or infection). Minor skin irritation has also been reported due to contact with zirconium powder. If it comes in contact with eyes, then it may warrant medical attention.
•The metal attains the property of a superconductor (a conductor that offers zero resistance to current; for this it must attain a certain temperature called the "critical temperature") when alloyed with niobium (soft, gray, ductile transition metal - more to come soon).
•The metal shares similar properties with titanium. However, the former has higher density and melting temperature than that of the latter.

Uses for Zirconium

# Zirconium is the source of the closest mimic of diamond - Cubic Zirconia (CZ). It is popularly fashioned as a diamond simulant (non-diamond material).

# Given the metal's low absorption of neutrons, and significant resistant towards heat and chemical corrosion, it is widely used in the working of nuclear reactors. Here the metal is used to provide an outer covering to components such as the fuel rods that run the reactor. As a matter of fact the nuclear power industry exploits 90% of the metal produced each year.

# As the metal is extremely high on the corrosion-resistance factor, it finds its applications in many industries which make use of corrosive agents such as in high-performance pumps, valves, etc.

# Zirconium oxide or zirconia, is mainly used in the manufacture of ceramic materials. It is an inorganic metal oxide, and a compound of zirconium. It is also used as a gemstone as it has a high refractive index.

# The main sources of zirconium are the minerals called zircon (ZrSiO4) and baddeleyite (ZrO2). A process known as the Kroll process is applied to obtain the metal from these minerals.

# Another use of zirconium is evident by black zirconium rings. These rings are available in elegant and luxurious designs for fashion-conscious people. These rings are scratch-resistant and do not sustain the wear and tear unlike other common metals.

# A common ingredient in antiperspirant is aluminum zirconium. It is, however, related to the development of breast cancer and Alzheimer's Disease. But there is no solid evidence to back this fact, and there are many controversies regarding the ill effects of the same.

# Zirconium also finds its application in steel as an alloying agent. Vacuum tubes, different surgical appliances, lamp filaments, piping, artificial joints and limbs require this metal. Apart from these, the metal is employed in photoflash bulbs, explosive primers, rayon spinnerets, etc.

Yttrium (39)

Yttrium (IT-REE-UM) has a silvery-metallic luster. Yttrium turnings ignite in air. Yttrium is found in most rare-earth minerals. Moon rocks contain yttrium and yttrium is used as a "phosphor" to produce the red color in television screens.

•Name: Yttrium
•Symbol: Y
•Atomic number: 39
•Atomic weight: ...88.90585
•Standard state: solid at 298 K
•CAS Registry ID: 7440-65-5
•Group in periodic table: 3
•Period in periodic table: 5
•Block in periodic table: d-block
•Color: silvery white
•Classification: Metallic

Historical information

Yttrium was discovered by Johann Gadolin at 1794 in Finland. Origin of name is the village of "Ytterby" near Vaxholm in Sweden. Yttria (yttrium oxide, Y2O3), was discovered by Johann Gadolin in 1794 in a mineral called gadolinite from Ytterby. Ytterby is the site of a quarry in Sweden which contains many unusual minerals containing erbium, terbium, and ytterbium as well as yttrium. Friedrich Wohler obtained the impure element in 1828 by reduction of the anhydrous chloride (YCl3) with potassium.

Physical properties

•Melting point: 1799 [or 1526 °C (2779 °F)] K
•Boiling point: 3609 [or 3336 °C (6037 °F)] K
•Density of solid: 4472 kg m-3

Orbital properties

•Ground state electron configuration: [Kr].4d1.5s2
•Shell structure: 2.8.18.9.2
•Term symbol: 2D3/2

Isolation

Yttrium metal is available commercially so it is not normally necessary to make it in the laboratory. Yttrium is found in lathanoid minerals and the extraction of the yttrium and the lanthanoid metals from the ores is highly complex. Initially, the metals are extracted as salts from the ores by extraction with sulphuric acid (H2SO4), hydrochloric acid (HCl), and sodium hydroxide (NaOH). Modern purification techniques for these lanthanoid salt mixtures involve selective complexation techniques, solvent extractions, and ion exchange chromatography.

Pure yttrium is available through the reduction of YF3 with calcium metal.

2YF3 + 3Ca → 2Y + 3CaF2

Interesting Facts...

Yttrium (English/French/German/Swedish) Ittrio (Italian) Ytrio (Spanish)

Yttrium is often used to make alloys with other metals. An alloy is made by melting and mixing two or more metals. The mixture has properties different from those of the individual metals. Two of yttrium's most interesting applications are in lasers and superconducting materials.

A laser is a device for producing very bright light of a single color. One of the most popular lasers is made of yttrium, aluminum, and garnet. One of the most widely used lasers today is the yttrium-aluminum-garnet (YAG) Laser. YAG Lasers often contain other elements. These elements change the kind of light produced by the laser in one way or another. The Laser is said to be doped with another element if it contains a small amount of that element. An example of this kind of laser is one doped with neodymium. The neodymium-doped YAG (Nd:YAG) laser has been used to make Long distance measurements (for my 2171 friends - think of the MULE and the range finders).

Garnet is a gem-like material with a sand-like composition. Superconducting materials are substances with no resistance to the flow of an electric current. An electric current that begins to flow through them never stops. Superconducting materials may have many very important applications in the future.

Yttrium phosphors have long been used in color television sets and in computer monitors.

None of the radioactive isotopes of yttrium has any important commercial use. However, yttrium-90 is now being tested as a treatment for cancer. Radiation given off by the isotope kills cancer cells. Researchers believe that yttrium-90 may find wider use in the future for treating cancer. One advantage of using this isotope is that is easy to obtain. It is produced when another radioactive isotope (strontium-90) breaks down. Strontium-90 is a by-product formed in nuclear power plants.