of 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 they 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.
Table of contents
metals in chemistry
metal of 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 (< it results about from the fact 10
eV) that metal atoms cannot be connected like many nonmetals by atomic bonds to molecules or lattices. If necessary in metal steams such atomic bonds seem, to z. B. sodium steam exists to approximately 1% out well 2 - molecules. 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 , D. h. 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.
from the kind of connection and the lattice structure result the following typical characteristics of the metals:
- 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 to occur, can it the whole before taken up energy again emit. Thus the gloss develops)
- for property 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
- property electrical conductivity by easily adjustable electrons
- property thermal conductivity by easily adjustable electrons
to bloom and boiling temperatures
the following table shows the bloom and boiling temperatures of some metals (in °C with normal print):
|Metal||fusing temperature||boiling temperature|
as high-melting one designates metal, their melting point T E over 2000K and/or. over the melting point of platinum (T E - platinum = 2045K = 1772°C) lies.
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 one approx. twenty-way higher heat conductivity than manganese. Further values.
Besides straight for the chemical behavior the affiliation to main or Nebengruppen of the periodic system is crucial.
|Rb||SR||Y||Zr||Nb||Mo||Tc||Ru||RH||Pd||AG||CD||in||SN||self-service||of width unit||I||Xe|
|of light alloys < 5 g/cm ³||heavy metals < 10 g/cm ³||heavy metals > 10 g/cm ³|
see also: Refraktärmetalle
In the earth's crust against it the nonmetals 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, so that a dismantling is worthwhile itself.
the connections or also solutions of different metals are called alloys. These have often completely different physical and chemical characteristics than the pure metals. Above all the hardness is partly higher around orders of magnitude. Likewise often the corrosion resistance is clearly increased. Pure metals are practically not used, except conductions with the production, since pure metals possess the largest conductivity. Here unalloyed metals, above all copper and aluminum are used.
With nonmetals such as hydrogen, carbon and nitrogen also storage connections are formed, whereby the nonmetal atoms are in gaps of the metal lattice, without changing this substantially. These storage connections keep the typical metal characteristics like the electrical conductivity.
Metal cations, v. A. those the Nebengruppenmetalle, form with Basen (water, ammonia, halides, cyanide and. v. A.) complex connections, whose stability cannot be explained alone by the electrostatic attraction.
Metals in higher Oxidationsstufen form also complex anions, z. B. chrome tri oxide CrO 3 separates in caustic potash solution under education chromate - of the anion CrO 4 2: CrO 3 + 2 KOH -> K 2 CrO 4 + H 2 O
many metals are important materials. Our modern world would be impossible without metals. Without reason phases of the mankind development are not called after the used materials Steinzeit , Bronzezeit , Eisenzeit.
The following list does not contain the most important metals and alloying constituents, connections.
- Aluminum: most important light alloy
- beryllium: Alloys, particularly with copper and aluminum, weapon technology
- bismuth: Alloys
- lead: Alloys, lead-acid battery, plumb bobs, corrosion protection, weight
- cadmium: A component of accumulators
- chrome: Alloying constituent (Chrom-Vanadium-Stahl, chromium-nickel stainless steel), coat metal
- iron: most important work metal (cast iron, steel), many alloys
- gallium: Semiconductor
- gold: Decoration metal, gold foil, electro-technology, value plant, currency security
- Indium: Semiconductor, seal
- iridium: Electrodes, spark plugs, Kugelschreiberminen (balls)
- potassium: alloyed with sodium as cooling agents in nuclear reactors
- cobalt: Magnets
- copper: Electro-technology (second highest conductivity after silver), bronze, brass
- magnesium: for particularly light workpieces with not all too-high requirements in terms of the firmness; One-way lightning pears and/or. Flashlight powder
- manganese: Alloying constituent (manganese steel)
- molybdenum: Alloying constituent (molybdenum steel) for the increase of the heat resistance
- sodium: alloyed with potassium as cooling agents in nuclear reactors
- nickel: Alloys (nickel iron, nickel chrome, nickel copper etc.), alloying constituent (Chrom-Vanadium-Stahl, chromium-nickel stainless steel), magnets
- osmium: alloyed with tungsten in lamps
- palladium: Catalysis, hydrogen storage
- platinum: Decoration metal, catalysis, most valuable metal
- mercury: Thermometer
- rhodium: Decoration metal
- ruthenium: Catalyst, increase of the degree of hardness of platinum and palladium
- silver: Decoration metal, photography
- tantalum: Condensers
- titanium: for lightweight construction way without consideration at the expense, decoration
- uranium: Nuclear reactors, radioactivity, projectiles
- vanadium: Alloying constituent (Chrom-Vanadium-Stahl) for heat resistant steel, catalyst for synthesizing of sulfuric acid (vanadium V oxide)
- tungsten: Lamps (highest melting point of all metals), special steel, tungsten carbide
- zinc: Alloying constituent (brass), die-cast zinc parts (Zamak alloy), galvanization of stealing hurry (hot-dip galvanizing, volume galvanizing,…)
- tin: Alloying constituent (bronze), plumb bobs (tin solder), tinplate, tin figures
- zirconium: Lamdasonde in the car (measurement of the oxygen content in the exhaust gas)
metal as civilization development characteristic
on the basis the manners of processing and use of metals important epochs of the Menscheitsgeschichte are differentiated.
Generally is this:
of metals in the astronomy
in the astronomy designates metal each chemical element with an ordinal number more highly than helium. This distinction is meaningful, since hydrogen and helium as well as some traces of lithium are the only elements, which are present after the Big Bang in the universe. All further elements result then for example in stars from nuclear fusion or from Supernovae. The Metallizität of objects of space can be understood therefore as indicator for its stellar activity.
metal in Chinese philosophy
metal marks an element of the traditional five-element teachings.
|Wiktionary: Metal - word origin, synonyms and translations|
Web on the left of
- animations of the atoms of metals and nonmetals: http://www.physik.rwth-aachen.de/~harm/aixphysik/atom/Periodic/index.html