Non Traditional Groupings of Metals by 72b3i16T


									                         NON-IUPAC CLASSIFICATION OF METALS
Coinage Metals
A Group 11 element is one in the series of elements in group 11 in the periodic table, consisting of transition
metals which are the traditional coinage metals of copper (Cu), silver (Ag), and gold (Au). They are also known as
the "noble metals." The name "coinage metals" can be somewhat misleading as various nations have used probably
dozens of metals (including stainless steel, lead, and zinc) in coins. They are all relatively inert, corrosion-resistant
metals which have been used for minting coins, hence their name.
 These metals, especially silver, have unusual properties that make them essential for industrial applications outside
of their monetary or decorative value. They are all excellent conductors of electricity. The most conductive of all
metals are silver, copper and gold in that order. Silver is also the most thermally conductive element, and the most
light reflecting element. Silver also has the unusual property that the tarnish that forms on silver is still highly
electrically conductive.
Copper is used extensively in electrical wiring and circuitry. Gold contacts are sometimes found in precision
equipment for their ability to remain corrosion-free. Silver is used widely in mission-critical applications as electrical
contacts, and is also used in photography (because silver nitrate reverts to metal on exposure to light),
agriculture, medicine, audiophile and scientific applications.
Gold, silver, and copper are quite soft metals and so are easily damaged in daily use as coins. Precious metal may also
be easily abraded and worn away through use. In their numismatic functions these metals must be alloyed with
other metals to afford coins greater durability. The alloying with other metals makes the resulting coins harder, less
likely to become deformed and more resistant to wear.
Gold coins: Gold coins are typically produced as either 90% gold (e.g. with pre-1933 US coins), or 22 carat (92%)
gold (e.g. current collectible coins and “Krugerrands”), with copper and silver making up the remaining weight in
each case. Bullion gold coins are being produced with up to 99.999% gold (in the Canadian Gold Maple Leaf series).
Silver coins: Silver coins are typically produced as either 90% silver - in the case of pre 1965 US minted coins (which
were circulated in many countries), or sterling silver (92.5%) coins for pre-1967 British Commonwealth and other
silver coinage, with copper making up the remaining weight in each case.
Copper coins: Copper coins are often of quite high purity, around 97%, and are usually alloyed with small amounts of
zinc and tin.
Because the face value of coins has fallen below the hard currency value of the historically used metals, this had led
to most modern coins being made of base metals - Cupro-nickel (around 80:20, silver in color) is popular as are
nickel-brass (copper (75), nickel (5) and zinc (20), gold in color), manganese-brass (copper, zinc, manganese, and
nickel), bronze, or simple plated steel.
Heavy Metals
       Types                     Characteristics                            Uses                          Effects
Lead (Pb)              -metallic and cubic close-packed          -protective shield from       -mental retardation among
                       -soft bluish white metal                   radioactivity                 children exposed to lead in
                       -non combustible solid (except as         -lead acid accumulator         water resulting from lead
                        dust)                                    -manufacture antiknock,        pipes and solders in older
                       -routes of exposure: inhalation,           tetraethyl lead Pb(C2H5)4 in water systems
                        ingestion, skin and/or eye contact        petrol                       -exhibit weakness, general
                       -target organs: gastrointestinal          -pigments e.g., white basic    disability, nervous
                        tract, central nervous system,            lead carbonate, Pb(OH)2       disorders and eventual
                        kidneys, blood and gingival tissue        orange pigment ‘red lead’,    death
Mercury (Hg)                                                 -electrodes in the                 -carcinogenic, typically
                       -silver colored liquid transition
                                                              amalgamation of                    cause cancer or are
                                                              electrolysis of brine              mutagenic
                       -non-combustible liquid
                                                             -thermometers                      -cause for kidney damage
                       -routes of exposure: inhalation, skin
                                                             -barometers                        -cause for neurological
                        absorption, ingestion, skin and/or
                                                             -fluorescent lamps                  disorder
                        eye contact
                                                                                                -cause for blindness
                       -target organs: eyes, skin,
                                                                                                -associated with birth
                        respiratory system, central
                        nervous system, kidneys
                                                                                                -damaging to aquatic life
Arsenic (As)           -metalloid and gray brittle non-          -deadly poison in shotgun      -carcinogenic
                        metal flake                               pellets                       -associated with lung cancer
                       -routes of exposure: inhalation,          -metal for mirrors             -results in skin cancer
                        ingestion, skin and/or eye contact.      -glass                         -damage to intestines and
                       -target organs: skin, respiratory         -lasers                         liver, as it is found in
                        system, kidneys, central nervous         -light emitting diodes (LED)    pesticides, wood
                        system, liver, gastrointestinal tract,   -semiconductors                 preservatives and naturally
                        reproductive system                                                      occurring in many
                                                                                                 household products
                                                                                                -toxic when ingested
Cadmium (Cd)           -silvery white transition metal           -nickel-cadmium batteries      -toxic and poisonous
                       -non-combustible solid (except as         -nuclear reactor regulator
                        dust)                                    -red/yellow pigments
                       -route of exposure: inhalation,
                        target organs: respiratory system,
                        kidneys, blood, prostate

Platinum Group
The platinum group (alternatively, the platinum group metals or platinum metals) is a collective name sometimes
used for six metallic elements clustered together in the periodic table. These elements are all transition metals, lying
in the d-block (groups 8, 9, and 10, periods 5 and 6. The six platinum group metals are ruthenium, rhodium,
palladium, osmium, iridium, and platinum. They have similar physical and chemical properties, and tend to occur
together in the same mineral deposits.
The platinum metals have outstanding catalytic properties. They are highly resistant to wear and tarnish, making
platinum, in particular, well suited for fine jewelry. Other distinctive properties include resistance to chemical attack,
excellent high-temperature characteristics, and stable electrical properties. All these properties have been exploited
for industrial applications.
Sperrylite (platinum arsenide, PtAs2) ore is a major source of this metal. A naturally occurring platinum-iridium alloy,
platiniridium, is found in the mineral cooperite (platinum sulfide, PtS). Platinum in a native state, often accompanied
by small amounts of other platinum metals, is found in alluvial and placer deposits in Colombia, Ontario, the Ural
Mountains, and in certain western American states. Platinum is also produced commercially as a by-product of nickel
ore processing. The huge quantities of nickel ore processed makes up for the fact that platinum makes up only two
parts per million of the ore. South Africa, with vast platinum ore deposits in the Merensky Reef of the Bushveld
complex, is the world's largest producer of platinum, followed by Russia.
Iridiosmium is a naturally occurring alloy of iridium and osmium found in platinum-bearing river sands in the Ural
Mountains and in North and South America. Trace amounts of osmium also exist in nickel-bearing ores found in the
Sudbury, Ontario region along with other platinum group metals. Even though the quantity of platinum metals found
in these ores is small, the large volume of nickel ores processed makes commercial recovery possible.
Metallic iridium is found with platinum and other platinum group metals in alluvial deposits. Naturally occurring
iridium alloys include osmiridium and iridiosmium, both of which are mixtures of iridium and osmium. It is recovered
commercially as a by-product from nickel mining and processing.
Ruthenium is generally found in ores with the other platinum group metals in the Ural Mountains and in North and
South America. Small but commercially important quantities are also found in pentlandite extracted from Sudbury,
Ontario and in pyroxenite deposits in South Africa. Ruthenium is commercially isolated through a complex chemical
process in which hydrogen is used to reduce ammonium ruthenium chloride yielding a powder. The powder is then
consolidated by powder metallurgy techniques or by argon-arc welding.
The industrial extraction of rhodium is complex as the metal occurs in ores mixed with other metals such as
palladium, silver, platinum, and gold. It is found in platinum ores and obtained free as a white inert metal which is
very difficult to fuse. Principal sources of this element are located in river sands of the Ural Mountains, in North and
South America and also in the copper-nickel sulfide mining area of the Sudbury Basin region. Although the quantity at
Sudbury is very small, the large amount of nickel ore processed makes rhodium recovery cost effective. However, the
annual world production of this element is only 7 or 8 tons and there are very few rhodium minerals.
Palladium is found as a free metal and alloyed with platinum and gold with platinum group metals in placer deposits
of the Ural Mountains, Australia, Ethiopia, South and North America. However it is commercially produced from
nickel-copper deposits found in South Africa and Ontario. The huge volume of nickel-copper ore processed makes
this extraction profitable in spite of its low concentration in these ores.
Platinum, platinum alloys, and iridium are used as crucible materials for the growth of single crystals, especially
oxides. The chemical industry uses a significant amount of either platinum or a platinum-rhodium alloy catalyst in the
form of gauze to catalyze the partial oxidation of ammonia to yield nitric oxide, which is the raw material for
fertilizers, explosives, and nitric acid.
In recent years, a number of platinum-group metals have become important as catalysts in synthetic organic
chemistry. Ruthenium dioxide is used as coatings on dimensionally stable titanium anodes used in the production of
chlorine and caustic.
Platinum supported catalysts are used in the refining of crude oil, reforming, and other processes used in the
production of high-octane gasoline and aromatic compounds for the petrochemical industry. Since 1979, the
automotive industry has emerged as the principal consumer of platinum-group metals. Palladium, platinum, and
rhodium have been used as oxidation catalyst in catalytic converters to treat automobile exhaust emissions. A wide
range of platinum-group metal alloy compositions are used in low-voltage and low-energy contacts, thick- and thin-
film circuits, thermocouples and furnace components, and electrodes.
Poor Metals (or Post-Transition Metals). Applied to the metallic elements in the p-block of the
periodic table. They have lower melting and boiling points, a higher electronegativity value, and are softer than
transition metals. The grouping includes aluminum, gallium, indium, lead, thallium, and tin. Sometimes antimony,
germanium, and polonium are included in this group of poor metals but these three are really properly considered

Radioactive Metals

Rare Earth Metals
Rare earth elements and rare earth metals are a collection of sixteen chemical elements in the periodic table,
namely scandium, yttrium, and fourteen of the fifteen lanthanoids (excluding promethium), which naturally occur on
the Earth. Scandium, yttrium are included as they tend to occur with the lanthanoids in the same ore deposits. Some
definitions additionally include the actinoids. The terms "rare earth" and "rare earth metal" fall outside the official
IUPAC nomenclature system, however, the terms retain their usability in the classification of metal alloys and other
compounds, as well as distinguishing rare-earth magnets from other types of magnet.
Rare earth elements became known to the world with the discovery of the black mineral gadolinite by Lieutenant
Karl Arrhenius in the year 1887, in a quarry in the village of Ytterby, Sweden. Many of the rare earths are named in
honor of the scientists who discovered the elemental properties, geographical discovery, Latin or Greek, or
Cerium (after Greek deity of fertility, Ceres.)
Dysprosium (from the Greek "dysprositos" meaning hard to get.)
Gadolinium (Johan Gadolin (1760-1852), to honor his investigation of rare earths.)
Lanthanum (from the Greek "lanthanon" meaning I am hidden.)
Neodymium (from a Greek word "neo" which means new-one.)
Praseodymium (from the Greek "praso" which means leek-green.)
Promethium (after Prometheus who brought fire to mortals.)
Samarium (V.E. Samarsky, discovered the rare-earth ore called samarskite.)
Thulium (refers to the mythological land of Thule.)
Ytterbium (named after the Ytterby, Sweden, where the first rare earth ore was discovered.)
"Earth" is an obsolete term for oxide; it is a translation from the French terre as French was the lingua franca when
these elements were discovered at the beginning of the 19th century. "Rare" was used because some of these
elements were believed to be scarce in abundance as minerals. However these elements are (except highly-unstable
promethium) relatively abundant in the Earth's crust; the most abundant, cerium, at 68 parts per million, is the 25th
most abundant element in the crust, more common than lead, while even the least abundant "rare" earth element,
lutetium, is 200 times more abundant than gold.
The principal economic sources of rare earth elements are the rare-earth minerals bastnasite, monazite, and loparite
and the lateritic ion-adsorption clays. Despite their relative abundance, however, these are more difficult to mine
and extract than the sources of transition metals (due in part to their very similar chemical properties), making them
relatively expensive. Their industrial use was very limited until efficient separation techniques were developed, such
as ion exchange, fractional crystallization and liquid-liquid extraction during the late 50's and early 60's.
The following abbreviations are often used:
REE = rare earth elements
LREE = light rare earth elements (La-Sm)
HREE = heavy rare earth elements (Eu-Lu)
Toxic metals are metals that form poisonous soluble compounds and have no biological role (are not essential
minerals). Often heavy metals are thought of as synonymous, but lighter metals also have toxicity, as exemplified by
beryllium, and not all heavy metals are particularly toxic and some are even essential (such as iron). The definition
may also include trace elements when considered in abnormally high, toxic doses. A difference is that there is no
beneficial dose for a toxic metal with no biological role.
Toxic metals imitate the action of an essential element in the body, distorting the metabolic process to cause illness.
Many metals, particularly heavy metals are toxic, but some heavy metals are essential, have a low toxicity, and
bismuth is even non-toxic. Most often the definition includes at least cadmium, lead, mercury and the radioactive
metals. Metalloids (arsenic, polonium) may be included in the definition. Radioactive metals have both radiation
toxicity and chemical toxicity. Metals in an oxidation state abnormal to the body may also become toxic: chromium
(III) is an essential trace element, but chromium (VI) is a carcinogen. The toxicity is a function of solubility, so that as
insoluble salts or even in the metallic form, toxic metals may have negligible toxicity. On the other hand, organo-
metallic forms, such as dimethyl mercury and tetraethyl lead, are extremely toxic. Toxic metals bioaccumulate in the
body and in the food chain. The exceptions are barium and aluminum. Therefore, a common characteristic of toxic
metals is the chronic nature of their toxicity.
Toxic metals: Barium, Beryllium, Aluminum , Cadmium, Lead - lead poisoning, Mercury - mercury poisoning,
Thallium, Antimony; Radioactive metals: Thorium, Uranium; The transuraniums, such as plutonium, americium, etc.
Polonium (a metalloid); Radioactive isotopes of lighter elements, e.g. cobalt-60. Arsenic (see arsenic poisoning) is a
metalloid. Trace elements with toxicity: Chromium as hexavalent Cr(VI); Nickel; Copper; Iron.

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