Metal
Metal
A metal is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typically malleable or ductile.
A metal (from Greek μέταλλον métallon, "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typically malleable (they can be hammered into thin sheets) or ductile (can be drawn into wires). A metal may be a chemical element such as iron, an alloy such as stainless steel, or a molecular compound such as polymeric sulfur nitride.
In physics, a metal is generally regarded as any substance capable of conducting electricity at a temperature of absolute zero.
In chemistry, two elements that would otherwise qualify (in physics) as brittle metals—arsenic and antimony—are commonly instead recognised as metalloids due to their chemistry (predominately non-metallic for arsenic, and balanced between metallicity and nonmetallicity for antimony).
In astrophysics the term "metal" is cast more widely to refer to all chemical elements in a star that are heavier than the lightest two, hydrogen and helium, and not just traditional metals. In this sense the first four "metals" collecting in stellar cores through nucleosynthesis are carbon, nitrogen, oxygen, and neon, all of which are strictly non-metals in chemistry.
The history of refined metals is thought to begin with the use of copper about 11,000 years ago. Gold, silver, iron (as meteoric iron), lead, and brass were likewise in use before the first known appearance of bronze in the 5th millennium BCE.
There are three main types of metals ferrous metals, non ferrous metals and alloys. Ferrous metals are metals that consist mostly of iron and small amounts of other elements. Ferrous metals are prone to rusting if exposed to moisture. Ferrous metals can also be picked up by a magnet.
A metal’s melting temperature, more scientifically known as the melting point, is the temperature that a metal begins to transform from a solid phase into a liquid phase. At the melting temperature, the solid phase and liquid phase of a metal exist in equilibrium. Once this temperature is achieved, heat can be continuously added to the metal, however this will not raise the overall temperature. Once the metal is completely in the liquid phase, additional heat will again continue to raise the temperature of the metal.
These are the melting temperatures of common metal types:
Aluminum: 660°C (1220°F)
Brass: 930°C (1710°F)
Aluminum Bronze*: 1027-1038°C (1881-1900°F)
Chromium: 1860°C (3380°F)
Copper: 1084°C (1983°F)
Gold: 1063°C (1945°F)
Inconel*: 1390-1425°C (2540-2600°F)
Cast Iron: 1204°C (2200°F)
Lead: 328°C (622°F)
Molybdenum: 2620°C (4748°F)
Nickel: 1453°C (2647°F)
Platinum: 1770°C (3218°F)
Silver: 961°C (1762°F)
Carbon Steel*: 1425-1540°C (2597-2800°F)
Stainless Steel*: 1375 – 1530°C (2500-2785°F)
Titanium: 1670°C (3038°F)
Tungsten: 3400°C (6152°F)
Zinc: 420°C (787°F)
Some of the cheapest found metal are Iron and Steel, Aluminium, Copper, Zinc, Lead, Cadmium, Manganese and Magnesium, to name among the few. On earth, the most abundant metal is aluminum.
Comments
Post a Comment