What is metal? The nature of this substance was interested in antiquity. About 96 types of metals are now discovered. We will talk about their characteristics and properties in the article.
What is metal?
The greatest number of elements in the periodic tablerefers to metals. Currently, man knows only 96 of their species. Each of them has its own characteristics, many of which have not yet been studied.
Что такое металл?This is a simple substance, which is characterized by high electrical and thermal conductivity, positive temperature coefficient of conductivity. Most metals have high strength, ductility and amenable to forging. One of the distinguishing features is the presence of metallic luster.
The meaning of the word "metal" is associated with the Greekmétallion, where it means "digging out of the ground", as well as "mine, save." In Russian terminology, it came during the reign of Peter I from German (German: Metall), into which the word moved from Latin.
Physical properties
Metal elements usually have goodplasticity, with the exception of tin, zinc, manganese. By density, they are divided into light (aluminum, lithium) and heavy (osmium, tungsten). Most have a high melting point, the total range ranges from -39 for mercury to 3410 degrees Celsius for tungsten.
Under normal conditions, all metals except mercury andfrance are solid. The degree of their hardness is determined in points according to the Moss scale, where the maximum is 10 points. So, the hardest are tungsten and uranium (6.0), the softest is cesium (0.2). Many metals have silvery, bluish and gray shades, only some are characterized by yellow and reddish colors.
В их кристаллических решетках находятся подвижные electrons, thanks to which they conduct electricity and heat perfectly. Silver and copper work best with this. The lowest thermal conductivity has mercury.
Chemical properties
Chemical properties of metals are divided intomany groups. Among them are alkaline, alkaline earth, light, actinium and actinides, lanthanum and lanthanides, semimetals. Separately, are magnesium and beryllium.
As a rule, metals act asreducing agents for nonmetals. They have different activities, so the reactions to substances are not the same. The most active are alkali metals, they easily interact with hydrogen, water.
Under certain conditions almost always happens.interaction of metals with oxygen. The reaction to it is absent only in gold and platinum. They also do not react to sulfur and chlorine, unlike other metals. The alkaline group is oxidized in an ordinary environment, the rest when exposed to high temperatures.
Being in nature
In nature, metals are found mainly in ores.or compounds, for example, oxides, salts, carbonates. Before use, they undergo lengthy cleaning steps. Many metals accompany mineral deposits. So, cadmium is a part of zinc ores, scandium and tantalum coexist with tin.
Сразу в чистом виде встречаются только инертные, that is, inactive metals. Due to their low susceptibility to oxidation and corrosion, they won the title of noble. These include gold, platinum, silver, ruthenium, osmium, palladium, etc. Precious metals are very plastic and have a characteristic bright luster in the finished products.
Metals surround us everywhere.In large quantities, they are in the earth's crust. The most common are aluminum, iron, sodium, magnesium, calcium, titanium and potassium. They are contained in sea water (sodium, magnesium), are part of living organisms. In the human body, metals are present in the bones (calcium), in the blood (iron), nervous system (magnesium), muscles (magnesium) and other organs.
Study and use
What is metal knew even ancient civilizations.Among the Egyptian archaeological finds, dating back to 3-4 millennia BC, were found products from precious metals. The first man discovered gold, copper, silver, lead, iron, tin, mercury. They served to make jewelry, tools, ritual objects and weapons.
In the Middle Ages, antimony was discoveredarsenic, bismuth, zinc. They are often given magical properties, associated with the cosmos, the movement of the planets. Alchemists conducted numerous experiments in the hope of turning mercury into water or gold. Gradually, the number of discoveries increased, and by the XXI century all known metals were discovered today.
Now they are used in almost all areasof life. Metals are used for the manufacture of jewelry, machinery, ships, cars. They make frames for the construction of buildings, produce furniture, various small parts.
Excellent electrical conductivity made the metal indispensable for the manufacture of wires, it is thanks to him, we use electric current.
