Metals

Metal, any of a class of substances characterized by high electrical and thermal conductivity as well as by malleability, ductility, and high reflectivity of light.

Approximately three-quarters of all known chemical elements are metals. The most abundant varieties in the Earth’s crust are aluminum, iron, calcium, sodium, potassium, and magnesium. The vast majority of metals are found in ores (mineral-bearing substances), but a few such as copper, gold, platinum, and silver frequently occur in the free state because they do not readily react with other elements.

Metals are used in:

• Transportation – cars, buses, trucks, trains, ships, and airplanes.
• Aerospace – unmanned and manned rockets and the space shuttle.
• Computers and other electronic devices that require conductors (TV, radio, stereo, calculators, security devices, etc.)
• Communications, including satellites that depend on a tough but light metal shell.
• Food processing and preservation – microwave and conventional ovens and refrigerators and freezers.
• Construction – nails in conventional lumber construction and structural steel in other buildings.
• Biomedical applications – as artificial replacement for joints and other prostheses.
• Electrical power production and distribution – boilers, turbines, generators, transformers, power lines, nuclear reactors, oil wells, and pipelines. Farming – tractors, combines, planters, etc.
• Household conveniences — Ovens, dish and clothes washers, vacuum cleaners, blenders, pumps, lawn mowers and trimmers, plumbing, water heaters, heating/cooling, etc.