Metals are a group of elements that have unique properties such as electrical conductivity, high heat transfer, positive resistance coefficient, characteristic luster and relative ductility. This type of substance is simple in terms of chemical compounds.
Classification by groups
Metals are among the most common materials used by mankind throughout its history. Most of them are located in the middle layers of the earth's crust, but there are also those that are hidden deep in mountain deposits.
Metals currently occupy most of the periodic table (94 out of 118 elements). Of the officially recognized groups, it is worth noting the following groups:
1. Alkaline (lithium, potassium, sodium, francium, cesium, rubidium). When in contact with water, they form hydroxides.
2. Alkaline earth (calcium, barium, strontium, radium). Differ in density and hardness.
3. Light (aluminum, lead, zinc, gallium, cadmium, tin, mercury). Often used in alloys due to low density.
4. transitional (uranium,gold, titanium, copper, silver, nickel, iron, cob alt, platinum, palladium, etc.). They have a variable oxidation state.
5. Semimetals (germanium, silicon, antimony, boron, polonium, etc.). They have a crystalline covalent lattice in their structure.
6. Actinides (americium, thorium, actinium, berkelium, curium, fermium, etc.).
7. Lanthanides (gadolinium, samarium, cerium, neodymium, lutetium, lanthanum, erbium, etc.).
It is worth noting that there are metals in the earth's crust and those that are not defined in groups. These include magnesium and beryllium.
Native compounds
In nature, there is a separate class of crystal-chemical codification. These elements include native metals. These are minerals that are not related to each other. Most often, native metals in nature are formed as a result of geological processes.
45 substances are known in the crystalline state in the earth's crust. Most of them are extremely rare in nature, hence their high cost. The share of such elements is only 0.1%. It should be noted that finding these metals is also a laborious and expensive process. It is based on the use of atoms with stable shells and electrons.
Native metals are also called noble. They are characterized by chemical inertia and stability of compounds. These include gold, palladium, platinum, iridium, silver, ruthenium, etc. Copper is most often found in nature. Iron in its native state is present mainly in mountain deposits in the form of meteorites. by the mostrare elements of the group are lead, chromium, zinc, indium and cadmium.
Basic Features
Almost all metals under normal conditions are hard and resistant. The exception is francium and mercury, alkali metals. The melting temperature for all elements of the group is different. Its range ranges from -39 to +3410 degrees Celsius. Tungsten is considered the most resistant to melting. Its compounds lose their resistance only at temperatures above +3400 C. Lead and tin should be distinguished from easily molten metals.
Also, elements are divided according to density (light and heavy) and plasticity (hard and soft). All metal compounds conduct electricity very well. This property is due to the presence of crystal lattices with active electrons. Copper, silver and aluminum have the maximum conductivity, sodium has a slightly lower conductivity. It is worth noting the high thermal properties of metals. Silver is considered the best heat conductor, mercury is the worst.
Metals in the environment
Most often, these elements can be found in the form of compounds and ores. Metals in nature form sulfites, oxides, carbonates. To purify the compounds, it is first necessary to isolate them from the composition of the ore. The next step will be alloying and final processing.
In industrial metallurgy, ferrous and non-ferrous ores are distinguished. The former are built on the basis of iron compounds, the latter on other metals. Platinum, gold and silver are considered precious metals. Most of them are in the earth's crust. Howeverto a lesser extent, sea water also accounts for a small proportion.
There are noble elements even in living organisms. A person contains about 3% of metal compounds. For the most part, the body contains sodium and calcium, which act as an intercellular electrolyte. Magnesium is necessary for the normal functioning of the central nervous system and muscle mass, iron is good for blood, copper is good for the liver.
Finding metal compounds
Most of the elements are located under the top layer of soil everywhere. The most common metal in the earth's crust is aluminum. Its percentage varies within 8.2%. Finding the most common metal in the earth's crust is not difficult, since it occurs in the form of ores.
Iron and calcium are slightly less common in nature. Their percentage is 4.1%. Next come magnesium and sodium - 2.3% each, potassium - 2.1%. The remaining metals in nature occupy no more than 0.6%. It is noteworthy that magnesium and sodium can be equally mined both in the ground and in sea water.
Metal elements in nature are found in the form of ores or in a native state, like copper or gold. There are substances that need to be obtained from oxides and sulfides, for example, hematite, kaolin, magnetite, galena, etc.
Metal production
The procedure for extracting elements comes down to extracting minerals. Finding metals in nature in the form of ores is the simplest and most common process in general industry. For searchcrystalline deposits, special geological equipment is used to analyze the composition of substances in a particular piece of land. More rarely, the presence of metals in nature is reduced to a banal open-pit underground method.
After mining, the enrichment stage begins, when ore concentrate is separated from the original mineral. Wetting, electric current, chemical reactions, heat treatment are used to distinguish elements. Most often, the release of metal ore occurs as a result of melting, that is, heating with recovery.
Aluminum mining
Non-ferrous metallurgy is engaged in this process. In terms of consumption and production, it is a leader among other branches of heavy industry. The most common metal in the earth's crust is in great demand in the modern world. In terms of production, aluminum is second only to steel.
Most of all, this element is used in the aviation, automotive and electrical industries. It is noteworthy that the most common metal in the earth's crust can also be obtained by "artificial" means. For such a chemical reaction, bauxites are required. They form alumina. By combining this substance with carbon electrodes and fluoride s alt under the action of an electric current, you can get the purest aluminum ore.
China is the leading country among the producers of this component. Up to 18.5 million tons of metal are smelted there annually. The Russian-Swiss association UC RUSAL is the leader in a similar aluminum mining rating.
Use of metals
All elements of the group are durable, impermeable and relatively resistant to temperature. That is why metals are so common in everyday life. Today they are used to make electrical wires, resistors, appliances, and household items.
Metals are ideal construction and tool materials. In construction, pure and combined alloys are used. In engineering and aviation, the main connections are steel and harder bonds.
