METALS AND NONMETALS

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METALS AND NONMETALS

There are some distinctions between metals and nonmetals. Metals are distinguished from nonmetals by their high conductivity for heat and electricity, by metallic luster and by their resistance to electric current. Their use in industry is explained not only by those properties, but also by the fact that their properties, such as strength and hardness, can be greatly improved by alloying them with other metals.

There are several important groups of metals and alloys. The common metals such as iron, copper, zinc, etc. are produced in great quantities.

The so-called precious metals include silver, gold, platinum and palladium. The light metals are aluminium, beryllium and titanium. They are important in aircraft and rocket construction.

Many elements are classified as semimetals (bismuth, for example) because they have much poorer conductivity than common metals.

Nonmetals (carbon, silicon, sulphur) in the solid state are usually brittle materials without metallic luster and are usually poor conductors of electricity. Nonmetals show great variety of chemical properties than common metals do.

Metals can undergo corrosion, changing in this case their chemical and electromechanical properties. In order to protect metals from corrosion the products made of metals and steel are coated by some films (coatings). Organic coatings protect metals and steel from corrosion by forming a corrosion-resistant barrier between metal or steel and the corrosive environment.

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