Out of 118 elements known to man, 94 are metals. These are elements that form simple substances with a characteristic brilliance, high plasticity and malleability. What other properties do metals have? What groups are they divided into? Let's find out.
Metals and their properties
Describing metals is not easy. They are difficult to compare with other elements or substances known in the modern world. In the standard sense, metal is a solid gray substance with a strong luster. But everything is much more complicated. Most of them are really gray, but the shades are different for everyone. Gallium is bluish, bismuth is pink, copper is bright red, but cesium, strontium and gold have a yellow tint.
Metals are very different in terms of the degree of manifestation of their properties. But there are qualities that unite them. Metals donate electrons to the outer level relatively easily, since they are weakly bound to the atomic nucleus. Their internal structure is represented by a crystal lattice, therefore, under normal conditions, they are all solid. The only exception is mercury, which hardens only at temperatures below -38.83°C.
Metals are excellent conductors of heat and electricity. Many of them are very plastic, such as gold, copper, pure chromium, silver. They are able to bend or crumple without breaking. Others are quite brittle (manganese, tin, bismuth).
Metal groups
Under the same conditions, metals behave differently, which can already be seen in the example of mercury. It becomes liquid very easily, but not all substances behave in the same way. Depending on the melting point, fusible and refractory metals are distinguished. The latter include tungsten, tantalum, rhenium, molybdenum. They melt at temperatures above 2000 °C.
Heavy and light metals are also isolated. Heavy - lead, cadmium, cob alt, mercury, copper, vanadium, have a large atomic weight (more than 50) and high density. The lungs are exactly the opposite. These include aluminum, gallium, indium. Lithium is the lightest, with a density of 0.533 g/cm³ and an atomic mass of 3.
In the Periodic table, the alkaline group of metals (lithium, sodium, potassium, rubidium) is also distinguished. They react quite easily with water to form a soluble alkali or hydroxide. All of them are very active, soft and much lighter than water. There are also alkaline earth metals (calcium, barium, strontium), alkali with water already forms their oxides or earths. They are harder and not as active as alkaline ones.
Based on the different properties of metals, they are also divided into:
- Transitional.
- Post transitional.
- Colored.
- Black.
- Lanthanides.
- Actinides.
- Noble.
- Platinum group metals.
- Rare earth.
Precious Metals
Metals often act as reducing agents in chemical reactions. By giving up their electrons, they undergo corrosive processes that destroy them. Under the action of oxidizing agents, oxides, hydroxides, are formed on their surface, which are popularly called rust.
Many metals are subject to such processes. Destroyers for them can be gases and various liquids. However, there is a separate class of metals that are practically resistant to oxidation and rust. These are noble metals. All of them are also rare and precious. Their prices range from $300 (silver) to $70,000 (rhodium) per kilo.
Noble are gold, silver, and platinum group metals: platinum, ruthenium, osmium, palladium, iridium, rhodium. Platinum, palladium, gold and silver are very plastic, but they cannot withstand too high temperatures. The rest of the noble metals are also refractory, melting from 2334°C (ruthenium) to 3033°C (osmium).
All of them are resistant to water and air, but can react with more aggressive substances. For example, silver dissolves easily in nitric acid, and darkens when it comes into contact with iodine. By the way, with the help of iodine, you can check whether the product is really silver.
Being in nature
Metals are widespread on our planet. in the form of s alts andcompounds they are found in sea water. Most of all, it is full of magnesium (0.12%) and calcium (1.05%). The most abundant metal in the earth's crust is aluminum. It makes up about 8% of its total mass. It is also high in iron (4.1%), calcium (4%), sodium (2.3%), magnesium (2.3%), potassium (2.1%).
But metals are present not only in the external environment. They are present in any living organism, responsible for many vital functions. The human body contains about 3% of metals. Iron in the blood helps hemoglobins to attach oxygen and exchange with carbon dioxide. Magnesium is found in the muscles and nervous system. It is involved in the synthesis of proteins, is responsible for muscle relaxation, inhibits the excitation of nerve endings.
The most necessary for us: magnesium, iron, sodium, calcium, potassium, zinc, copper, cob alt, manganese and molybdenum. Metals are found in the bones, in the brain, in the tissues of other organs. We get them from water and food, and constantly need to replenish their stocks. With a deficiency of these elements, the body does not work properly, however, their excess is also not good.
Application
People have learned to use metals in almost all areas of their lives. Structural materials, wires, electrical engineering, dishes are made from them. Unstable radioactive elements such as uranium, californium, polonium have found use in nuclear power and weapons production.
Light and strong metals are used in space technology and the automotive industry. Various elements are used inpharmaceutical, food and textile industries. They are used to make jewelry, household items, as well as medicines and medical instruments. Lithium, for example, is used as an antidepressant, gold is included in the remedies for arthritis and tuberculosis. Titanium and tantalum are used in surgery to make prostheses and replace damaged parts of the body.
