معلومات عن النحاس

Name: Copper Symbol: Cu
Type: Transition Metal Atomic weight: 63.546
Density @ 293 K: 8.96 g/cm3 Atomic volume: 7.1 cm3/mol
Discovered: Copper has been known since ancient times and has been used by people for over ten thousand years. The Copper Age sits between the Neothilic (Stone) and Bronze Ages. The Copper Age took place at different times in different cultures, when people began using copper tools alongside stone tools. The word copper is derived from the Latin word 'cuprum' meaning 'metal of Cyprus'. The Mediterranean island of Cyprus was an ancient source of mined copper.

States
State (s, l, g): solid
Melting point: 1357.77 K (1084.62 oC) Boiling point: 2833 K (2560 oC)



Energies
Specific heat capacity: 0.38 J g-1 K-1 Heat of atomization: 338 kJ mol-1
Heat of fusion: 13.050 kJ mol-1 Heat of vaporization: 300.30 kJ mol-1
1st ionization energy: 745.4 kJ mol-1 2nd ionization energy: 1957.9 kJ mol-1
3rd ionization energy: 3553.5 kJ mol-1 Electron affinity: 118.5 kJ mol-1
Oxidation & Electrons
Shells: 2,8,18,1 Electron configuration: [Ar] 3d10 4s1
Minimum oxidation number: 0 Maximum oxidation number: 4
Min. common oxidation no.: 0 Max. common oxidation no.: 2
Electronegativity (Pauling Scale): 1.95 Polarizability volume: 6.7 Å3



Small and large samples of copper foil like this, as well as sheet, wire, insulated wire, mesh, and rod (and copper alloy in foil, sheet, and wire form) can be purchased from Advent Research Materials via their web catalogue.


The result of adding different metal salts to a burning reaction mixture of potassium chlorate and sucrose. The red colour originates from strontium sulphate. The orange/yellow colour originates from sodium chloride. The green colour originates from barium chlorate and the blue colour originates from copper (I) chloride. The lilac colour that should be evident from the potassium chlorate is washed out by the other colours, all of which are more intense (only to be demonstrated by a professionally qualified chemist following a legally satisfactory hazard asessment). Improperly done, this reaction is dangerous!

Copper (I) chloride salts imparts a blue colour to flames. The picture above shows the colour arising from adding cuprous chloride (CuCl) to a burning mixture of potassium chlorate and sucrose. This flame is relatively cool. Hotter flames burn green bacause of emission from copper atoms (only to be demonstrated by a professionally qualified chemist following a legally satisfactory hazard asessment).
Isolation

Isolation: copper metal is readily available commercially so it is not normally necesary to make it in the laboratory. Most copper production is based upon sulphide ores containing little copper but quite a lot of iron. New cleaner technologies are now important but older processes present major environmental problems. Complex procedures are used initially to form a form of copper sulphide appropriate for final reduction via a copper(I) oxide. The resulting crude copper is purified using an electrolytic procedure involving plating onto pure copper cathodes.

2Cu2S + 3O2 → 2Cu2O + 2SO2

2Cu2O + Cu2S → 6Cu + SO2

Notably, the purification step leaves an "anode slime" which contains useful amounts of silver and gold.
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