An amalgam is an alloy of mercury with another metal. Most metals are soluble in mercury, but some (such as iron) are not. Amalgam also may be a solution of metal-like ion complexes, such as ammonium. Amalgams are commonly used in dental fillings. General Name, Symbol, Number mercury, Hg, 80 Chemical series transition metals Group, Period, Block 12, 6, d Appearance silvery Standard atomic weight 200. ... Amalgam Comics was a metafictional American comic book publisher, and part of a collaboration between Marvel Comics and DC Comics, in which the two comic book publishers merged their characters to create new ones (e. ... Amalgamation, meaning to combine or unite into one form, has several uses: Amalgam, in chemistry, mining and dentistry, the result of the blending of mercury with another metal or alloy Amalgamation (mining), the process of separation of precious metals from ore. ... An alloy is a homogeneous hybrid of two or more elements, at least one of which is a metal, and where the resulting material has metallic properties. ... General Name, Symbol, Number mercury, Hg, 80 Chemical series transition metals Group, Period, Block 12, 6, d Appearance silvery Standard atomic weight 200. ... This article is about metallic materials. ... It has been suggested that this article or section be merged with Solution. ... For other uses, see Iron (disambiguation). ... A ball-and-stick model of the ammonium cation Ammonium is also an old name for the Siwa Oasis in western Egypt. ... This article is about the dental profession. ...

Dentistry

Amalgam filling

For some centuries, dentists have been cleaning out decay and creating dental fillings using filling material such as stone chips, resin, cork, turpentine, gum, lead and gold leaf. The renowned physician Ambroise Paré (1510 – 1590) used lead or cork to fill teeth. Amalgams have been in wide use since the mid-1800s, when they became the first true standard filling material. Image File history File links Amalgam. ... Image File history File links Amalgam. ... X-rays can reveal if a person has cavities Dentistry is the practical application of knowledge of dental science (the science of placement, arrangement, function of teeth) to human beings. ... It has been suggested that this article or section be merged into dental restoration. ... This article does not cite any references or sources. ... A cork stopper for a wine bottle Champagne corks Varnished cork tiles can be used for flooring, as a substitute for linoleum or tiles. ... For the band, see Turpentine (band). ... Natural gums are polysaccharides of natural origin, capable of causing a large viscosity increase in solution, even at small concentrations. ... This article is about the metal. ... GOLD refers to one of the following: GOLD (IEEE) is an IEEE program designed to garner more student members at the university level (Graduates of the Last Decade). ... Ambroise Paré. Ambroise Paré (1510 – December 20, 1590) was a French surgeon, the official royal surgeon for kings Henry II, Francis II, Charles IX and Henry III, is considered by some as one of the Fathers of Surgery. ...

Amalgams are used in dentistry because they are cheap, easy to use, and more durable than many alternatives. They are generally regarded as safe, though this is not without controversy (see below). Modern low-copper amalgams have a powder component composed of 69.4% silver, 3.6% copper, 26.2% tin, and 0.8% zinc; and they have a liquid component of 42% to 45% mercury by weight^{[citation needed]}. The amalgam remains soft for a short time so it can be packed to fill any irregular volume, and then forms a hard compound. This article is about the chemical element. ... For other uses, see Copper (disambiguation). ... This article is about the metallic chemical element. ... General Name, symbol, number zinc, Zn, 30 Chemical series transition metals Group, period, block 12, 4, d Appearance bluish pale gray Standard atomic weight 65. ... General Name, Symbol, Number mercury, Hg, 80 Chemical series transition metals Group, Period, Block 12, 6, d Appearance silvery Standard atomic weight 200. ...

The first people to use amalgam to fill cavities were the Chinese in the 7th century.^[1] In 1816, Auguste Taveau developed a dental amalgam from silver coins and mercury. This early amalgam was low in mercury and had to be heated in order for the silver to dissolve at any appreciable rate. More modern dental amalgams are mixed cold. Current dental amalgams contain copper to eliminate the gamma-2 phase of the silver-mercury-tin alloy. The gamma-2 phase is weaker than the other phases, so a high-copper, low-gamma-2 dental amalgam has superior strength.

Dental amalgam controversy

Main article: Dental amalgam controversy

The Dental amalgam controversy is a debate over the use of amalgams, which contain mercury, as a dental filling. Though mercury itself is a potent neurotoxin, amalgam fillings are considered safe by most dentists. Recent random clinical trials have found no evidence of neurological harm associated with their use in children, examining a period of 5-7 years following treatment.^[2][3] Still, some worry about the difficulties of conclusively excluding the possibility of neurological effects.^[4] They point out that such effects may be delayed beyond the period examined in the studies; may be larger in a vulnerable subset of patients, such as those who are genetically predisposed to mercury sensitivity; or may simply have been lost in the noise of measurement. These concerns are especially significant considering the tremendous number of patients with amalgam fillings. Thus, while the studies cited provide strong evidence that there is little risk of large scale neurological harm for most patients, even a risk small enough to be easily missed could affect a large number of people. The Dental amalgam controversy is a debate over the use of amalgams, which contain mercury, as a dental filling. ... General Name, Symbol, Number mercury, Hg, 80 Chemical series transition metals Group, Period, Block 12, 6, d Appearance silvery Standard atomic weight 200. ... Dental fillings are inserted as restorations in the treatment of dental cavities, after drilling out the cavities. ...

Chemical analysis

Mercury is the preferred electrode material for the analysis of metals by anodic stripping voltammetry. The formation of amalgams facilitates the reduction of most metal ions in aqueous solutions that is normally not possible because their reduction potentials are more negative than the potential for the reduction of the solution. Voltammetry is a category of electroanalytical methods used in analytical chemistry and various industrial processes. ...

Use in organic chemistry

Formation of amalgams is used to increase the reactivity of metals. In the Grignard reaction, amalgamation of the magnesium makes the reaction more facile. In the Barbier reaction and other reactions using aluminum, it is absolutely necessary, as the surface oxide coating normally makes aluminum inert. The Grignard reaction is an organometallic chemical reaction involving alkyl- or aryl-magnesium halides, also called Grignard reagents, with electrophiles. ... General Name, symbol, number magnesium, Mg, 12 Chemical series alkaline earth metals Group, period, block 2, 3, s Appearance silvery white solid at room temp Standard atomic weight 24. ... The Barbier reaction is an organic reaction between a alkyl halide and a carbonyl group as an electrophilic substrate in the presence of aluminium, zinc, indium, tin or its salts. ... Aluminum is a soft and lightweight metal with a dull silvery appearance, due to a thin layer of oxidation that forms quickly when it is exposed to air. ...

Mining

Mercury has been used in the gold and silver mining processes due to the ease with which mercury will amalgamate with them. In gold placer mining, in which small particles of gold are washed from sand or gravel deposits, mercury was often used to separate the gold from other heavy minerals. GOLD refers to one of the following: GOLD (IEEE) is an IEEE program designed to garner more student members at the university level (Graduates of the Last Decade). ... This article is about the chemical element. ... Miners operate a hydraulic sluice in San Francisquito Canyon, Los Angeles County. ...

After all of the usable metal had been extracted from the ore, mercury was poured down a long copper trough which formed a thin coating of mercury on the surface. The waste ore was then poured down the trough, and any gold in the waste amalgamated with the mercury. This coating was occasionally scraped off and distilled to remove the mercury, leaving behind fairly high-purity gold.

Mercury amalgamation was first applied to silver ores with the invention of the patio process in Mexico in 1557. Other amalgamation processes were invented for processing silver ores, including pan amalgamation and the Washoe process. The patio process was a process used to refine silver from silver sulfide ores. ... The patio process was a process used to extract silver from silver sulfide ores. ... The patio process was a process used to extract silver from silver sulfide ores. ...

With the invention of mercury amalgamation to treat silver ore, mercury became essential to the silver mines of the New World. The Spanish Empire transported mercury from Almadén across the Atlantic to supply the silver mines of Zacatecas and Potosí. Another source for mercury in the Spanish Empire was the mine of Huancavelica in Peru, discovered in 1563. In 1648, the Viceroy of Peru declared that Potosí and Huancavelica were "the two pillars that support this kingdom and that of Spain."^[5] An anachronous map of the Spanish Empire (1492-1898). ... Almadén,Spain, is a town in the province of Ciudad Real, within the Autonomous Community of Castilla la Mancha. ... Zacatecas is a city in Mexico, the capital of the state of Zacatecas. ... Potosí is a city, the capital of the department of Potosí in Bolivia. ... Huancavelica is a city in Peru. ... A viceroy is a royal official who governs a country or province in the name of and as representative of the monarch. ...

Today, mercury amalgamation has been replaced by other methods to recover gold and silver from ore. Dangers of mercury pollution have played a part in the near-disappearance of mercury amalgamation processes. Mercury amalgamation is still commonly used by small-scale gold placer miners, especially in less-developed countries, most notably Brazil.

The amalgam table is used in gold productions and was the main way to collect fine particles of gold during the 1800s. The table is simply a sloped, smooth surface with a copper sheet overlaid and smeared with mercury. The pulp from the stamp battery is directed over the table. The finely crushed gold chemically bonds with the mercury, and hence sticks to the table for later collection. However, if there is any oil in the water, it will surround the gold and cause it to float away and not bond properly with the mercury.

Other uses

Thallium amalgam is used as liquid for thermometers, because it freezes at -58°C^{[citation needed]}, whereas pure mercury freezes at -38°C. General Name, Symbol, Number thallium, Tl, 81 Chemical series poor metals Group, Period, Block 13, 6, p Appearance silvery white Standard atomic weight 204. ... A thermometer is a device used to measure temperatures or temperature changes. ... Celsius is, or relates to, the Celsius temperature scale (previously known as the centigrade scale). ...

See also

• Sodium amalgam
• Mercury-aluminum amalgam

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In chemistry, sodium amalgam is an amalgam, or alloy of mercury, with sodium metal. ... A mercury-aluminum amalgam is a chemical reagent that uses aluminum coated with mercury to reduce compounds, such as the reduction of imines to amines. ... Wikipedia does not have an article with this exact name. ... Wiktionary (a portmanteau of wiki and dictionary) is a multilingual, Web-based project to create a free content dictionary, available in over 150 languages. ...

References

1. ^ American Dental Association, History of Dentistry [1]. Accessed May 29, 2006.
2. ^ Neurobehavioral effects of dental amalgam in children: a randomized clinical trial.. JAMA (2006). Retrieved on 2006-12-23.
3. ^ Neuropsychological and renal effects of dental amalgam in children: a randomized clinical trial.. JAMA (2006).
4. ^ Mercury in Dental Amalgam—A Neurotoxic Risk?. JAMA (2006).
5. ^ Arthur Preston Whitaker, The Huancavelica Mercury Mine: A Contribution to the History of the Bourbon Renaissance in the Spanish Empire, Harvard Historical Monographs 16 (Cambridge, MA: Harvard University Press, 1941).

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