Than metals are remarkable?
are known to mankind 118 chemical elements, from them 94 metals and 24 nonmetals Now. It is calculated that all again opened elements also have to be metals. Therefore, metals in Periodic system of elements the vast majority.
Except the iron forming group of ferrous metals together with alloys the others 84 treat color. However 84 elements are quite a lot, in turn, to divide non-ferrous metals on easy, heavy, noble, rare, radioactive. Allocate also groups alkaline, shchelochnozemelny, rare-earth, transitional, etc.
all elements with external d - and f - electron shells, and also entering into the main subgroups with the first on the fourth group of Periodic system belong To metals. What does it mean? Yes do not stuff yourself with it the head. Consider that this magic spell, in ordinary life absolutely not applicable. As a lot of things from what we for years learned are inapplicable. For example, trigonometry formulas.
As for such elements as carbon, phosphorus, arsenic, antimony, selenium, tellurium, etc., metal properties show only some of their modifications. And stability of nonmetals to a large extent depends on external conditions, for example, from pressure. It is proved that, applying ultrahigh pressure, it is possible to transfer any substance to a metal state.
Ultrahigh pressure and ultralow temperatures, achievable presently, allow to influence so strongly substance that typical dielectric becomes the conductor or even a superconductor. So in the conditions of ultrahigh pressure emergence of superconductivity even at xenon was recorded.
The crystal lattice of metals consists of the positively charged nuclear skeleton fastened with communication of metal type; around and in it “cloud“ of the delocalized electrons, so-called electronic gas is distributed. Such character of a chemical bond causes not only conductivity, but also high heat conductivity of metals. Heat removal from areas with more high temperature in less heated can be carried out by electrons owing to their high mobility.
In superpure metals at cryogenic temperatures length of free run of electrons tens of thousands times more, than at metals of technical purity. It opens an opportunity to use essentially new physical effects. As in metals quantity of electrons with which it is possible to operate i.e. to accelerate, brake or change their trajectory, in millions times more, than in semiconductors, it is expected that transition of electronics to a new material basis will be equivalent a gallop which occurred in due time upon transition from electronically - vacuum devices to semiconductor.
Not orientation of interatomic communications and plotnoupakovanny crystal structure of metals causes their ability to be deformed easily under the influence of mechanical efforts, i.e. to show property of plasticity.
The atoms, small by the size, introduced in structure are obstacles for movement of linear defects of crystal structure of metals - dislocations, thereby interfering with mechanical deformation of an alloy. This feature allows to increase the hardness of alloys significantly. Pure metals as in them layers of atoms can be displaced easier relatively each other are more plastic. Nevertheless and they have essential durability.
From the chemical point of view metals are, as a rule, unstable, easily are oxidized when heating, enter chemical interaction with nonmetals - carbon, nitrogen, sulfur, etc., and also form alloys with other metals and nonmetals.
But we will talk about alloys later.