Zirconium

Today I´m going to talk about zirconium

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.

Table: basic information about and classifications of zirconium.

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 Group name: (none) Period in periodic table: 5 Block in periodic table: d-block Colour: silvery white Classification: Metallic

 Small and large samples of zirconium foil like this, as well as sheet and wire, can be purchased from Advent Research Materials via their web catalogue.

Zirconium: historical information

Zirconium was discovered by Martin Heinrich Klaproth at 1789 in Berlin, Germany. Origin of name: from the Arabic word "zargun" meaning "gold colour".

                                  

 

 

 

 

 

 

The name zircon probably originated from the arabic "zargun", which describes the colour 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.

Zirconium: physical properties

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

 

Zirconium: orbital properties

• Ground state electron configuration:  [Kr].4d².5s²
• Shell structure:  2.8.18.10.2
• Term symbol:   ³F₂
• Pauling electronegativity: 1.33 (Pauling units)
•  First ionisation energy: 640.1 kJ mol^-1
•  Second ionisation energy:  1270 kJ mol^-1

 

Isolation

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 magensium 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.

Iridium

Today I´m going to talk about iridium

Ruthenium, rhodium, palladium, osmium, iridium, and platinum together make up a group of elements referred to as the platinum group metals (PGM).

The name iridium is appropriate, for its salts are highly coloured. Iridium is white, similar to platinum, but with a slight yellowish cast. It is very hard and brittle, making it very hard to machine, form, or work. It is the most corrosion resistant metal known, and was used in making the standard metre bar of Paris, which is a 90% platinum-10% iridium alloy. This metre bar has since been replaced as a fundamental unit of length (see Krypton).
Iridium is not attacked by any of the acids nor by aqua regia, but is attacked by molten salts, such as NaCl and NaCN.

Table: basic information about and classifications of iridium.

Name: Iridium Symbol: Ir Atomic number: 77 Atomic weight: 192.217 (3) Standard state: solid at 298 K CAS Registry ID: 7439-88-5

Group in periodic table: 9 Group name: Precious metal or Platinum group metal Period in periodic table: 6 Block in periodic table: d-block Colour: silvery white Classification: Metallic

 Small and large samples of iridium foil like this, as well as wire, can be purchased via their web catalogue from Advent Research Materials via their web catalogue.

Iridium: historical information

Iridium was discovered by Smithson Tennant, Antoine Fourcroy, Louis Vanquelin, Hippolyte Collet-Descotils at 1803 in England, France. Origin of name: from the Greek word "iris" meaning "rainbow".

                                 

 

Osmium was discovered in 1803 by Smithson Tennant in the dark coloured residue left when crude platinum is dissolved by aqua regia (a mixture of hydrochloric and nitric acid). This dark residue contains both osmium and iridium (named after the Latin word iris meaning rainbow because of the colourful nature of iridium compounds).

Iridium: physical properties

• Melting point: 2739 [or 2466 °C (4471 °F)] K
• Boiling point: 4701 [or 4428 °C (8002 °F)] K
• Density of solid: 22650 kg m^-3

 

Iridium: orbital properties

• Ground state electron configuration:  [Xe].4f¹⁴.5d⁷.6s²
• Shell structure:  2.8.18.32.15.2
• Term symbol:   ⁴F_9/2
• Pauling electronegativity: 2.20 (Pauling units)
•  First ionisation energy: 880 kJ mol^-1
•  Second ionisation energy: 1600 kJ mol^-1

 

Isolation

Isolation: it would not normally be necessary to make a sample of iridium in the laboratory as the metal is available, at a price, commercially. The industrial extraction of iridium is complex as the metal occurs in ores mixed with other metals such as rhodium, palladium, silver, platinum, and gold. Sometimes extraction of the precious metals such as iridium, rhodium, platinum and palladium is the main focus of a partiular industrial operation while in other cases it is a byproduct. The extraction is complex because of the other metals present and only worthwhile since iridium is useful as a specialist metal and is the basis of some catalysts in industry.

Preliminary treatment of the ore or base metal byproduct is required to remove silver, gold, palladium, and platinum. The residue is melted with sodium bisulphate (NaHSO₄) and the resulting mixture extracted with water to give a solution containing rhodium sulphate, Rh₂(SO₄)₃. The insoluble residue contains the iridium. The residue is melted with Na₂O₂ and extracted into water to remove ruthenium and osmium salts. The residue contains iridium oxide, IrO₂. Dissolution of the oxide in regia (a mixture of hydrochloric acid, HCl, and nitric acid, HNO₃) gives a solution containing pure (NH₄)₃IrCl₆. Evaporation to dryness and burning under hydrogen gas gives pure iridium.

Yttrium

Today I´m going to talk about yttrium

Yttrium has a silvery-metallic lustre. 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 colour in television screens.

Table: basic information about and classifications of yttrium.

Name: Yttrium Symbol: Y Atomic number: 39 Atomic weight: 88.90585 (2) Standard state: solid at 298 K CAS Registry ID: 7440-65-5

Group in periodic table: 3 Group name: (none) Period in periodic table: 5 Block in periodic table: d-block Colour: silvery white Classification: Metallic

Yttrium: historical information

Yttrium was discovered by Johann Gadolin at 1794 in Finland. Origin of name: named after 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.

Yttrium: 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

 

Yttrium: orbital properties

• Ground state electron configuration:  [Kr].4d¹.5s²
• Shell structure:  2.8.18.9.2
• Term symbol:   ²D_3/2
• Pauling electronegativity: 1.22 (Pauling units)
•  First ionisation energy: 600 kJ mol^-1
•  Second ionisation energy: 1180 kJ mol^-1

 

Isolation

Isolation: yttrium metal is available commercially so it is not normally necesary 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 extractedas 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

Mercury

Today I´m going to talk about mercury

Mercury is the only common metal liquid at ordinary temperatures. Mercury is sometimes called quicksilver. It rarely occurs free in nature and is found mainly in cinnabar ore (HgS) in Spain and Italy. It is a heavy, silvery-white liquid metal. It is a rather poor conductor of heat as compared with other metals but is a fair conductor of electricity. It alloys easily with many metals, such as gold, silver, and tin. These alloys are called amalgams. Its ease in amalgamating with gold is made use of in the recovery of gold from its ores.

The most important salts are mercuric chloride HgC1₂ (corrosive sublimate - a violent poison), mercurous chloride Hg₂Cl₂ (calomel, occasionally still used in medicine), mercury fulminate (Hg(ONC)₂, a detonator used in explosives), and mercuric sulphide (HgS, vermillion, a high-grade paint pigment).
Organic mercury compounds are important - and dangerous. Methyl mercury is a lethal pollutant found in rivers and lakes. The main source of pollution is industrial wastes settling to the river and lake bottoms.
As mercury is a very volatile element, dangerous levels are readily attained in air. Mercury vapour should not exceed 0.1 mg m^-3 in air. Air saturated with the vapour at 20°C contains mercury in a concentration far greater than that limit. The danger increases at higher temperatures. It is therefore important that mercury be handled with care. Containers of mercury should be securely covered and spillage should be avoided. Mercury should only be handled under in a well-ventilated area. If you are in possession of any mercury you are advised to contact a properly qualified chemist or public health laboratory for its safe disposal.
Small amounts of mercury spillage can be cleaned up by addition of sulphur powder. The resulting mixture should be disposed of carefully.

The result of burning ammonium dichromate, (NH₄)₂Cr₂O₇, containing pellets of mercuric thiocyanate (HgCNS). This is a large scale version of the indoor firework "Serpents in the grass" (only to be demonstrated by a professionally qualified chemist following a legally satisfactory hazard asessment). Improperly done, this reaction is dangerous! Llighting not great - sorry.

 

Table: basic information about and classifications of mercury.

Name: Mercury Symbol: Hg Atomic number: 80 Atomic weight: 200.59 (2) Standard state: liquid at 298 K (the heaviest known elemental liquid) CAS Registry ID: 7439-97-6

Group in periodic table: 12 Group name: (none) Period in periodic table: 6 Block in periodic table: d-block Colour: silvery white Classification: Metallic

Mercury: historical information

Mercury was discovered by Known since ancient times at no data in not known. Origin of name: named after the planet "Mercury" (the origin of the symbol Hg is the Latin word "hydrargyrum" meaning "liquid silver").

                                              

 

 

 

 

 

Mercury was known to ancient Chinese and Hindus before 2000 BC and was found in tubes in Egyptian tombs dated from 1500 BC It was used to forma amalgams of other metals around 500 BC. The Greeks used mercury in ointments and the Romans used it, unfortunately for those using it, in cosmetics.

Mercury is one of the elements which has an alchemical symbol, shown below (alchemy is an ancient pursuit concerned with, for instance, the transformation of other metals into gold).

Sometime prior to the autumn of 1803, the Englishman John Dalton was able to explain the results of some of his studies by assuming that matter is composed of atoms and that all samples of any given compound consist of the same combination of these atoms. Dalton also noted that in series of compounds, the ratios of the masses of the second element that combine with a given weight of the first element can be reduced to small whole numbers (the law of multiple proportions). This was further evidence for atoms. Dalton's theory of atoms was published by Thomas Thomson in the 3rd edition of his System of Chemistry in 1807 and in a paper about strontium oxalates published in the Philosophical Transactions. Dalton published these ideas himself in the following year in the New System of Chemical Philosophy. The symbol used by Dalton for mercury is shown below. [See History of Chemistry, Sir Edward Thorpe, volume 1, Watts & Co, London, 1914.]

 

Mercury: physical properties

• Melting point: 234.32 [or -38.83 °C (-37.89 °F)] K
• Boiling point: 629.88 [or 356.73 °C (674.11 °F)] K
• Density of solid: 14190 kg m^-3

 

Mercury: orbital properties

• Ground state electron configuration:  [Xe].4f¹⁴.5d¹⁰.6s²
• Shell structure:  2.8.18.32.18.2
• Term symbol:   ¹S₀
• Pauling electronegativity: 2.00 (Pauling units)
•  First ionisation energy: 1007.1 kJ mol^-1
•  Second ionisation energy: 1810 kJ mol^-1

 

Isolation

Isolation: the physical appearance of mercury is well known because of its use in many thermometers. It was common to demonstrate the formation of mercury in the laboratory by heating mercury sulphide (cinnabar, HgS) but this is strongly discouraged today because of the toxicity of mercury vapours. Don't do it! However, this method forms the basis of commercial extraction. The prepared cinnabar ore is heated in a current of air and the mercury vapour condensed.

HgS + O₂ (600°C) → Hg (l) + SO₂ (g)

The crude mercury is then washed with nitric acid and treated with air in order to remove impurities as oxides or into solution. Further purification is achieved by distillation at reduced pressure.

Manganese

Today I´m going to talk about manganese

 

Manganese metal is gray-white, resembling iron, but is harder and very brittle. The metal is reactive chemically, and decomposes cold water slowly. Manganese is widely distributed throughout the animal kingdom. It is an important trace element and may be essential for utilisation of vitamin B. Manganese is present in quantity the floor of oceans. It is an important component of steel.

Table: basic information about and classifications of manganese.

Name: Manganese Symbol: Mn Atomic number: 25 Atomic weight: 54.938045 (5) Standard state: solid at 298 K CAS Registry ID: 7439-96-5

Group in periodic table: 7 Group name: (none) Period in periodic table: 4 Block in periodic table: d-block Colour: silvery metallic Classification: Metallic

Manganese: historical information

Manganese was discovered by Johann Gahn at 1774 in Sweden. Origin of name: from the Latin word "magnes" meaning "magnet", or "magnesia nigri" meaning "black magnesia" (MnO₂).

                             

 

 

 

Manganese metal was isolated by Gahn in 1774. He reduced the dioxide (MnO₂, as the mineral pyrolusite) with charcoal (essentially carbon) by heating and the result was a sample of the metal manganese.

Manganese: physical properties

• Melting point: 1519 [or 1246 °C (2275 °F)] K
• Boiling poin: 2334 [or 2061 °C (3742 °F)] K
• Density of solid: 7470 kg m^-3

 

Manganese: orbital properties

• Ground state electron configuration:  [Ar].3d⁵.4s²
• Shell structure:  2.8.13.2
• Term symbol:   ⁶S_5/2
• Pauling electronegativity: 1.55 (Pauling units)
•  First ionisation energy: 717.3 kJ mol^-1
•  Second ionisation energy: 1509.0 kJ mol^-1

 

Isolation

Isolation: it is not normally necessary to make manganese in the laboratory as it is available commercially. Nearly all manganese produced commercially is used in the steel industry as ferromanganese. This made by the reduction of iron oxide, Fe₂O₃, and managanese dioxide, MnO₂, in appropriate proportions with carbon (as coke) in a blast furnace. Pure manganese is available through the electrolysis of manganese sulphate, MnSO₄,

Lead

Today I´m going to talk about lead

Lead is a bluish-white lustrous metal. It is very soft, highly malleable, ductile, and a relatively poor conductor of electricity. It is very resistant to corrosion but tarnishes upon exposure to air. Lead pipes bearing the insignia of Roman emperors, used as drains from the baths, are still in service. Alloys include pewter and solder. Tetraethyl lead (PbEt₄) is still used in some grades of petrol (gasoline) but is being phased out on environmental grounds.

Lead isotopes are the end products of each of the three series of naturally occurring radioactive elements.

Table: basic information about and classifications of lead.

Name: Lead Symbol: Pb Atomic number: 82 Atomic weight: 207.2 (1) Standard state: solid at 298 K CAS Registry ID: 7439-92-1

Group in periodic table: 14 Group name: (none) Period in periodic table: 6 Block in periodic table: p-block Colour: bluish white Classification: Metallic

Lead: historical information

Lead was discovered by Known since ancient times at no data in not known. Origin of name: from the Anglo-Saxon word "lead; Latin, plumbum" (the origin of the symbol Pb is the Latin word "plumbum" meaning "liquid silver".

                                  

 







Lead has been known for ages and is mentioned in Exodus. Alchemists believed lead to be the oldest metal and associated it with the planet Saturn. They spent a lot of time trying to "transmute" lead into gold.

Lead is one of the elements which has an alchemical symbol, shown below (alchemy is an ancient pursuit concerned with, for instance, the transformation of other metals into gold).

Sometime prior to the autumn of 1803, the Englishman John Dalton was able to explain the results of some of his studies by assuming that matter is composed of atoms and that all samples of any given compound consist of the same combination of these atoms. Dalton also noted that in series of compounds, the ratios of the masses of the second element that combine with a given weight of the first element can be reduced to small whole numbers (the law of multiple proportions). This was further evidence for atoms. Dalton's theory of atoms was published by Thomas Thomson in the 3rd edition of his System of Chemistry in 1807 and in a paper about strontium oxalates published in the Philosophical Transactions. Dalton published these ideas himself in the following year in the New System of Chemical Philosophy. The symbol used by Dalton for lead is shown below. [See History of Chemistry, Sir Edward Thorpe, volume 1, Watts & Co, London, 1914.]

 

Lead: physical properties

• Melting point: 600.61 [or 327.46 °C (621.43 °F)] K
• Boiling point: 2022 [or 1749 °C (3180 °F)] K
• Density of solid: 11340 kg m^-3

 

Lead: orbital properties

• Ground state electron configuration:  [Xe].4f¹⁴.5d¹⁰.6s².6p²
• Shell structure:  2.8.18.32.18.4
• Term symbol:   ³P₀
• Pauling electronegativity: 2.33 (Pauling units)
•  First ionisation energy: 715.6 kJ mol^-1
•  Second ionisation energy:  1450.5 kJ mol^-1

 

Isolation

Isolation: there is usually little need to make lead metal in the laboratory as it is so cheap and readily available. Lead is isolated from the sulphide, PbS. The process involves burning in a restricted air flow followed by reduction of the resulting oxide PbO with carbon.

PbS + ³/₂O₂ → PbO + SO₂

PbO + C → Pb + CO

PbO + CO → Pb + CO₂

This gives lead usually contaminated with metals such as antimony, arsenic, copper, gold, silver, tin, and zinc. A fairly complex process is used to strip out these impurities.

Platinum

Today I´m going to talk about platinum

Ruthenium, rhodium, palladium, osmium, iridium, and platinum together make up a group of elements referred to as the platinum group metals (PGM).

Platinum is a beautiful silvery-white metal, when pure, and is malleable and ductile. It has a coefficient of expansion almost equal to that of soda-lime-silica glass, and is therefore used to make sealed electrodes in glass systems.
The metal does not oxidise in air. It is insoluble in hydrochloric and nitric acid, but dissolves when they are mixed as aqua regia, forming chloroplatinic acid (H₂PtCl₆), an important compound. It is corroded by halogens, cyanides, sulphur and alkalis. Hydrogen and oxygen gas mixtures explode in the presence of platinum wire.

Table: basic information about and classifications of platinum.

Name: Platinum Symbol: Pt Atomic number: 78 Atomic weight: 195.084 (9) Standard state: solid at 298 K CAS Registry ID: 7440-06-4

Group in periodic table: 10 Group name: Precious metal or platinum group metal Period in periodic table: 6 Block in periodic table: d-block Colour: greyish white Classification: Metallic

Platinum: historical information

Platinum was discovered by Antonio de Ulloa at 1735 in South America. Origin of name: from the Spanish word "platina" meaning "silver".    
         

               

                                      

                     

                                                                 

The metal was used by pre-Columbian Indians but platinum was "rediscovered" in South America by Ulloa in 1735 and by Wood in 1741. In 1822 plenty of platinum was discovered in the Ural Mountains in Russia.

Platinum is one of the elements which has an alchemical symbol, shown below
Sometime prior to the autumn of 1803, the Englishman John Dalton was able to explain the results of some of his studies by assuming that matter is composed of atoms and that all samples of any given compound consist of the same combination of these atoms. Dalton also noted that in series of compounds, the ratios of the masses of the second element that combine with a given weight of the first element can be reduced to small whole numbers (the law of multiple proportions). This was further evidence for atoms. Dalton's theory of atoms was published by Thomas Thomson in the 3rd edition of his System of Chemistry in 1807 and in a paper about strontium oxalates published in the Philosophical Transactions. Dalton published these ideas himself in the following year in the New System of Chemical Philosophy. The symbol used by Dalton for platinum is shown below. [See History of Chemistry, Sir Edward Thorpe, volume 1, Watts & Co, London, 1914.]

 

Platinum: physical properties

• Melting point: 2041.4 [or 1768.3 °C (3214.9 °F)] K
• Boiling point: 4098 [or 3825 °C (6917 °F)] K
• Density of solid: 21090 kg m^-3

 

Platinum: orbital properties

• Ground state electron configuration:  [Xe].4f¹⁴.5d⁹.6s¹
• Shell structure:  2.8.18.32.17.1
• Term symbol:   ³D₃
• Pauling electronegativity: 2.28 (Pauling units)
•  First ionisation energy: 870 kJ mol^-1
•  Second ionisation energy: 1791 kJ mol^-1

 

Isolation

Isolation: it would not normally be necessary to make a sample of platinum in the laboratory as the metal is available commercially. The industrial extraction of platinum is complex as the metal occurs in ores mixed with other metals such as palladium and gold. Sometimes extraction of the precious metals such as platinum and palladium is the main focus of a partiular industrial operation while in other cases it is a byproduct. The extraction is complex and only worthwhile since platinum is the basis of important catalysts in industry.

Preliminary treatment of the ore or base metal byproduct with aqua regia (a mixture of hydrochloric acid, HCl, and nitric acid, HNO₃) gives a solution containing complexes of gold and palladium as well as H₂PtCl₆. The gold is removed from this solution as a precipitate by treatment with iron chloride (FeCl₂). The platinum is precipitated out as impure (NH₄)₂PtCl₆ on treatment with NH₄Cl, leaving H₂PdCl₄ in solution. The (NH₄)₂PtCl₆ is burned to leave an impure platinum sponge. This can be purified by redissolving in aqua regia, removal of rhodium and iridium impurities by treatment of the solution with sdoium bromate, and precipitation of pure (NH₄)₂PtCl₆ by treatment with ammonium hydroxide, NH₄OH. This yields platinum metal by burning.

Zinc

Today I´m going to talk about zinc

Zinc-deficient animals require 50% more food to gain the same weight of an animal supplied with adequate amounts of zinc. Zinc is not particularly toxic and is an essential element in the growth of all animals and plants.

Plating thin layers of zinc on to iron or steel is known as galvanising and helps to protect the iron from corrosion.

Table: basic information about and classifications of zinc.

Name: Zinc Symbol: Zn Atomic number: 30 Atomic weight: 65.38 (2) Standard state: solid at 298 K CAS Registry ID: 7440-66-6

Group in periodic table: 12 Group name: (none) Period in periodic table: 4 Block in periodic table: d-block Colour: bluish pale grey Classification: Metallic

Zinc: historical information

Zinc was discovered by Andreas Marggraf at 1746 in Germany. Origin of name: from the German word "zink".

 

 

 

 

 

 

 

Centuries before zinc was recognized as a distinct element, zinc ores were used for making brass (a mixture of copper and zinc). A brass dating from between 1400-1000 BC has been found in Palestine. An alloy containing 87% zinc was found in prehistoric ruins in Transylvania. The smelting of zinc ores with copper was apparently discovered in Cyprus and was used later by the Romans. Metallic zinc was produced in the 13th century in India by reducing calamine (zinc carbonate, ZnCO₃) with organic substances such as wool.

The metal was rediscovered later in Europe. William Champion set up a zinc industry in Bristol (England) in the 1740s. Other plants were established a little later in Belgium and Silesia.
Sometime prior to the autumn of 1803, the Englishman John Dalton was able to explain the results of some of his studies by assuming that matter is composed of atoms and that all samples of any given compound consist of the same combination of these atoms. Dalton also noted that in series of compounds, the ratios of the masses of the second element that combine with a given weight of the first element can be reduced to small whole numbers (the law of multiple proportions). This was further evidence for atoms. Dalton's theory of atoms was published by Thomas Thomson in the 3rd edition of his System of Chemistry in 1807 and in a paper about strontium oxalates published in the Philosophical Transactions. Dalton published these ideas himself in the following year in the New System of Chemical Philosophy. The symbol used by Dalton for zinc is shown below. [See History of Chemistry, Sir Edward Thorpe, volume 1, Watts & Co, London, 1914.]

 

Zinc: physical properties

• Melting point: 692.68 [or 419.53 °C (787.15 °F)] K
• Boiling point: 1180 [or 907 °C (1665 °F)] K
• Density of solid: 7140 kg m^-3

 

Zinc: orbital properties

• Ground state electron configuration:  [Ar].3d¹⁰.4s²
• Shell structure:  2.8.18.2
• Term symbol:   ¹S₀
• Pauling electronegativity: 1.65 (Pauling units)
•  First ionisation energy: 906.4 kJ mol^-1
•  Second ionisation energy: 1733.3 kJ mol^-1

 

Isolation

Isolation: zinc metal is readily available commercially so it is not normally necesary to make it in the laboratory. Most zinc production is based upon sulphide ores. These are roasted in industrial plants to form zinc oxide, ZnO. This may be reduced with carbon to form zinc metal, but in practice ingenious technology is required to ensure that the resulting zinc does not contain oxide impurities.

ZnO + C → Zn + CO

ZnO + CO → Zn + CO₂

CO₂ + C → 2CO

The other type of extraction is electrolytic. Dissolution of crude zinc oxide, ZnO, in sulphuric acid gives zinc sulphate, ZnSO₄ in solution. Cadmium is an impurity and this is removed as a precipitate of cadmium sulphate by the addition of zinc dust. Electrolysis of the ZnSO₄ solution using aluminium cathodes and lead alloyed with silver anodes gives pure zinc metal coated on the aluminium. Oxygen gas is liberated at the anode.
Very pure zinc may be formed from crude zinc by zone refining and single crystals can be grown with purities of better than 99.9999%.