Metals are the largest group of the chemical elements, about 80 % of the elements are metals. They are generally good electrical conductor.

In the periodic system of the elements metals are assigned to certain rows or periods, on the contrary they are on the left of and below a line from the boron to the polonium. Right above the nonmetals are, between them the metalloids. The side group elements are without exception metals.

Metals in chemistry

Fundamental

Metal atoms are characterized by the following characteristics:

• The number of the electrons in the outside bowl is small and smaller than the co-ordination number
• The ionization energy is small (< about 10 eV)

From it it results that metal atoms cannot be connected like many nonmetals by atomic bonds to molecules or lattices. If necessary in metal steams such atomic bonds occur, e.g. sodium steam consists of approximately 1 % of Metals arrange themselves rather to a metal lattice, in which the bonding electrons are distributed over the whole lattice, one speak also of an electron gas. In the electron gas arrange themselves positively charged atomic trunks. A more accurate view with consideration of the orbital model supplies the band model.

In connection with nonmetals the metals appear generally as cations, i.e. the outside electrons are transferred completely to the nonmetal atoms and it form an ionic compound (salt). At an ion lattice the ions are held together only by electrostatic forces.

Characteristics

From the kind of connection and the lattice structure the following typical characteristics of the metals result:

• Opacity by easily adjustable electrons (by it that the electrons are not bound to certain energy levels (orbital), but freely in form of an electron gas, can they occur many wavelengths absorb and have therefore one grey to black color)
• Gloss, under easily adjustable electrons at the surface (by it that the electrons are not bound to certain energy levels (orbital), but freely in form of an electron gas occur, can it the whole before taken up energy again emit. Thus the gloss develops)
• Good ductility (ductility): In the metal lattice are transfers, which can move with a tension below the separation tension; depending upon type of lattice thus a metal deforms rather, it breaks
• High melting point by the generally arranged binding forces
• Good electrical conductivity by easily adjustable electrons
• Good thermal conductivity by easily adjustable electrons

Bloom and boiling temperatures

The following table shows the bloom and boiling temperatures of some metals (in "°C with normal print):

High-melting one calls metals, whose melting point of width unit lies over 2000K and/or over the melting point of platinum (width unit platinum = 2045K = 1772"°C).

In addition the precious metals ruthenium, rhodium, osmium and iridium and metals of the groups of IVA (zirconium, hafnium) belong, to VA (vanadium, niobium, tantalum), VIA (chrome, molybdenum, tungsten) and VIIA (technetium, rhenium).

Heat guidance characteristics

The characteristics such as density, thermal capacity, heat conductivity and thermal diffusivity, relevant for the thermal conduction, vary strongly. So for instance silver with 427 w (m K) has a approx. twenty-way higher heat conductivity than manganese. Further values.

Organization

Traditionally one divides metals after the density in heavy metals and light alloys and after reactivity into precious metals and unedle metals. See also for this the major item metallic material.

Besides straight for the chemical behavior the affiliation to main or Nebengruppen of the periodic system is crucial.

See also:

Occurrence

The earth core consists mostly of iron, since it is the physically most stable element.

In the earth's crust against it the metals outweigh, relatively frequent metals are aluminum, iron, manganese, titanium, calcium, magnesium, sodium and potassium. Many rare metals arise however in their dismantling places strongly enriched. Rocks, which contain classical work metals in concentrations worthy of exploitation, are called ores. To the most important ores belong:

• Oxides
• Sulfides
• Carbonates

Other metal connections such as common salt or lime are not designated against it than ores.

Some precious metals, v. A. gold, occur also gediegen, i.e. in pure form and not as connection/ore.

Articles in category "Metal"

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