Metals

Of 107 known chemical elements of the Periodic System of Chemical Elements 85 - metals and only 22 - non-metals. Metals such as gold, silver and copper, are known man since prehistoric times. In the ancient and middle ages it was believed that there are only 7 metals (gold, silver, copper, tin, lead, iron and mercury). M.V. Lomonosov defined metal as "a bright body that can be forged" and referred to metals as gold, silver, copper, tin, iron and lead. A. Lavoisier in the "Initial Course of Chemistry" (1789) mentioned already 17 metals. At the beginning of the 19th century, the discovery of platinum metals, followed by alkaline, alkaline earth and a number of others.

Metals that were discovered as a result of predictions based on D. Mendeleyev's periodic law are gallium, scandium and germanium

Metals that were discovered as a result of predictions based on D. Mendeleyev's periodic law are gallium, scandium and germanium. In the middle of the 20th century, by means of nuclear reactions, transuranium elements were obtained - radioactive metals that did not exist in the period. Modern metallurgy receives over 75 metals and on their basis more than 5000 alloys.

Most of the metals are present in nature in the form of ores and compounds. They form oxides, sulphides, carbonates and other chemical compounds. For the production of pure metals and their further application, it is necessary to separate them from ores and carry out purification. If necessary, doping and other processing of metals. The study of this is the science of metallurgy. Metallurgy distinguishes ores of ferrous metals (based on iron) and non-ferrous (iron does not include them). Gold, silver and platinum also apply to precious metals. In addition, in small quantities they are present in sea water, plants, living organisms.

Metals are extracted from the earth in the process of mining. The extracted ores serve as a relatively rich source of necessary elements. To determine the location of ores in the earth's crust, special search methods are used, including prospecting and exploration of ore deposits. Deposits of ores are developed by open or quarry method and by underground or mine method. All metals (except mercury and, conditionally, France) under normal conditions are in a solid state, but they have different hardness, which is found on the Mohs scale.

Most metals are plastic, that is, the metal wire can be bent and it will not break. This is due to the displacement of the layers of metal atoms without breaking the bond between them. The most plastic are gold, silver and copper. All metals conduct electricity well; this is due to the presence in their crystal lattices of mobile electrons moving under the action of the electric field. Silver, copper and aluminum have the greatest electrical conductivity; for this reason the last two metals are most often used as a material for wires.

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