Copper and its alloys
How copper interacts with other compounds
Copper is a non-ferrous soft metal which has been used by humanity for several thousand years. Copper continues to play an important role and is widely used in industry and for other purposes.
General characteristics of the metal
Copper is found in the fourth major period and 11-th group of the periodic table. The atomic number of copper is 29, its atomic weight is 63.546. Copper has two stable natural isotopes, with the mass numbers 63 and 65. The Latin name of the element is cuprum, and the chemical symbol is Cu.
Copper has high ductility and is an excellent conductor of heat and electricity. Its melting temperature is 1084.62 degrees Celsius. The density of the metal is 8.96 g/cm3. In nature, the element is encountered both in minerals and in free form.
Chemical properties of copper
Copper is a rather chemically inert metal, with two oxidation states shown in compounds: +1 and +2.
Substances in which these values change to +3 are encountered rarely. Copper interacts with oxygen, hydrochloric acid and other compounds at high temperatures. Also, on heating a protective oxide film forms on the surface of the metal, which protects it from further oxidation. Copper interacts with simple substances: selenium, halogens and sulfur. The element can form complex compounds or binary salts. Almost all complex copper compounds are poisonous. Monovalent copper in various compounds readily oxidizes to bivalent copper.
Here you’ll find awesome experiments for learning properties of copper.
Copper alloys and their properties
Numerous alloys contain a copper base. When certain components are added, the properties of the copper alloy are significantly improved in comparison with pure copper.
The following alloys exist:
brass – a combination of copper and zinc in various ratios (this alloy has high durability and resistance to chemical impact);
bronze – a copper alloy with 12% tin;
cupronickel – an alloy of 5–30% nickel and copper;
constantan – an alloy of 45% nickel and 55% copper.
Copper(I) oxide is a brown-red solid substance with a molar mass of 143.09 g/mol. Its melting temperature is 1,232 degrees Celsius, and boiling temperature is 1,800 degrees Celsius. Copper oxide does not dissolve in water, but dissolves in acids. Copper(I) oxide is diluted in a concentrated solution of ammonia, forming the colorless complex [Cu(NH₃)₂]⁺, and easily oxidizes in air to an ammonium complex of a blue-violet color [Cu(NH₃)₄(H₂O)₂]²⁺, which dissolves in hydrochloric acid with the formation of CuCl₂. Copper(I) oxide can be obtained by the oxidation of copper in a lack of oxygen, the equation of the reaction is:
4Cu + O₂ → 2 Cu₂O.