All chemical elements of the periodic table are conventionally divided by the diagonal B - At into metals and non-metals. Moreover, the latter are in the minority, located above and to the right of the border. Metals are in obvious quantitative advantage; there are more than 80 of the known 118 elements.
All of them have similar physical properties, are united by an aggregate state. However, there is an exception - the mercury element. We’ll talk about it in more detail.
Mercury: position in the periodic system
This element occupies its cell in the table under the number 80. In this case, it is located in the second group, a subgroup, the sixth large period. It has an atomic mass of 200.59. It exists in the form of seven stable isotopes: 196, 198, 199, 200, 201, 202, 204.
Refers to elements of the d-family, but not transitional, since the last valence electrons fill the s-orbital. Mercury is a subgroup of zinc metals, along with cadmium and copernicium.
General characteristic of the element
The chemical elements of the periodic table have a strictly ordered arrangement, and each has its own electronic configuration of the atom, talking about its properties. Mercury is no exception. The structure of its external and external electronic shell is as follows: 5s 2 5p 6 5d 10 6s 2 .
Possible oxidation states: +1, +2. Mercury oxide and hydroxide are weakly basic, sometimes amphoteric in nature. The chemical symbol of element number 80 is Hg, the Latin pronunciation is "hydrargyrum". The Russian name comes from the Pre-Slavic language, in which it was translated as "roll". Other nations have different pronunciation and name. Often the element itself and the simple and complex substances formed by it are called mercury, mercury. This name comes from ancient times when Hg (element) was compared with silver, giving it a second meaning after gold. The sun is a symbol of Au Aurum, Mercury is a symbol of Hg hydrargyrum.
Ancient peoples believed that there were seven basic metals, among which mercury. A group of them was reflected in celestial bodies. That is, gold was associated with the Sun, iron with Mars, mercury with Mercury, and so on.
Discovery story
About mercury was known about 1500 BC. Even then, it was described as "liquid silver", a moving, unusual and mysterious metal. They also learned to extract it in ancient times.
Of course, it was not possible to study its properties, because chemistry was not yet formed as such. Mercury was shrouded in a veil of mystery and magic, it was considered an unusual substance, close to silver and able to turn into gold if it was made solid. However, there was no way to obtain pure mercury in a solid state of aggregation, and alchemical research was unsuccessful.
The main countries where mercury has been used and mined since antiquity are:
- China;
- Mesopotamia;
- India;
- Egypt.
However, it was possible to obtain this metal in its pure form only in the XVIII century, this was done by the Swedish chemist Brandt. At the same time, neither to them, nor until this moment have they been given evidence of the metallicity of the substance. This question was clarified by M.V. Lomonosov and Brown. It was these scientists who were the first to freeze mercury and thus confirm that it is characterized by all the properties of metals - gloss, electrical conductivity, malleability and ductility, metal crystal lattice.
To date, a variety of mercury compounds have been obtained; it is used in various fields of technical production.
Substance mercury
As a simple substance, it is a liquid (under normal conditions) silver-white, mobile, volatile. A typical example where pure liquid mercury is used is thermometers, thermometers for measuring temperature.
If mercury is transferred to a solid state, then it will be translucent, odorless crystals. Vapors of this substance are colorless, very toxic.
Physical properties
By its physical properties, this metal is the only representative that, under ordinary conditions, can exist in the form of a liquid. For all other properties, it fully fits the general characteristics of the remaining representatives of the category.
The main properties are as follows.
- Physical state: usual conditions - liquid, solid crystals - not higher than 352 , vapors - more than 79 K.
- It is soluble in benzene, dioxane, crystals in water. It has the ability not to wet the glass.
- It has diamagnetic properties.
- Heat conductive.
Melting of mercury occurs at a negative temperature of -38.83 ° C. Therefore, this substance belongs to the group of explosive when heated. In this case, the internal energy reserve of the compound increases several times.
Boiling of mercury begins at a temperature of 356.73 ° C. At this point, it begins to turn into a vaporous state, which is a molecule completely invisible to the eye, connected by a covalent non-polar bond.
The melting point of mercury indicates that the properties of this metal are clearly unusual. This substance begins to evaporate, passing into invisible molecules of a gaseous state, even at normal room temperature, which makes it especially dangerous for human and animal health.
Chemical properties
The following groups of mercury-based compounds are known in various oxidation states:
- sulfates, sulfides;
- chlorides;
- nitrates;
- hydroxides;
- oxides;
- complex compounds;
- organometallic substances;
- intermetallic;
- alloys with other metals - amalgams.
The melting point of mercury allows it to form both liquid and solid amalgams. In such alloys, metals lose their activity, becoming more inert.
Mercury reacts with oxygen only at a sufficiently high temperature, despite the strong oxidizing ability of non-metal. Under conditions above 380 ° C, as a result of such synthesis, metal oxide is formed with a degree of oxidation of the latter +2.
With acids, alkalis, non-metals in free form, the metal does not enter into chemical interaction, remaining in a liquid state.
Reacts with halogens rather slowly and only in the cold, which confirms the melting point of mercury. A good oxidizing agent for it is potassium permanganate.
Being in nature
Contained in the earth's crust, oceans, ores and minerals. If we talk about the total percentage of mercury in the earth's interior, then this is approximately 0.000001%. In general, we can say that this element is scattered. The main minerals and ores that comprise this metal are as follows:
- cinnabar;
- quartz;
- chalcedony;
- mica;
- carbonates;
- lead-zinc ores.
In nature, mercury circulates all the time and takes part in the metabolic processes of all the shells of the Earth.
Mercury production
The main method of obtaining is the processing of cinnabar mineral. A metallurgical process using reducing agents is also possible. When the first method is used, the mineral undergoes severe firing in oxygen. As a result, metal vapors are formed. Since the melting point of mercury is very low, and boiling, on the contrary, is high, the collection and condensation of vapors upon receipt of firing do not cause difficulties. This method of processing mercury sulfide was used in antiquity to obtain metal in its pure form.
The second method is based on the extraction of mercury also from sulfide using a strong reducing agent. Such as iron. Product collection is carried out in the same way as in the previous case.
Biological effects on living organisms
The temperature of mercury is needed low enough to go into a vapor state. This process begins already at 25 ° C, that is, at ordinary room temperature. In this case, the presence of living organisms in the room becomes hazardous to health.
So, metal is able to penetrate into creatures through:
- integuments intact, completely intact;
- mucous membranes;
- Airways;
- digestive organs.
Once inside, mercury vapors are included in the general bloodstream, and then enter into the synthesis of protein and other molecules, forming compounds with them. This is the accumulation of harmful metal in the liver and bones. From storage sites, the metal can again be included in metabolic processes, syntheses and decays, causing slow intoxication of the body, accompanied by the most serious consequences.
It is removed from organs rather slowly and under the influence of catalysts, adsorbents. For example, milk. The main liquids through which the metal is released into the environment:
- saliva;
- bile;
- urine;
- gastrointestinal tract products.
There are two main forms of poisoning with this substance: acute and chronic. Each has its own characteristics and manifestations.
Symptoms and treatment
The acute form is typical for cases when there is a spill of mercury in industries, that is, when a huge emission of matter into the atmosphere occurs at a time. In such situations, unprotected people begin to sharply worsen their health, that is, poisoning. Symptoms are as follows:
- Respiratory organs, lungs, mucous membranes of the mouth and throat become inflamed.
- Body temperature rises.
- Gums ulcers form, they bleed, swell and become extremely sensitive. Sometimes a mercury rim is formed.
- Atrophy of the liver and kidneys is observed.
- Chills, nausea and vomiting, dizziness.
- The nervous system suffers very much - speech and coordination of movements are disturbed, tremor of the limbs is observed.
- Poisoning is accompanied by headaches and diarrhea with blood inclusions.
If the defeat by mercury vapor occurs gradually, then the disease will become chronic. In this case, the manifestations will not be so sharp, however, deterioration in well-being will accumulate daily, taking on ever larger scale.
- Tremor of the limbs.
- Diseases of the oral cavity (gingivitis, stomatitis and others).
- Hypertension and tachycardia.
- Sweating.
- Nervous excitement.
- Headache.
- In severe cases, serious mental disorders, up to schizophrenia, can be provoked.
All these consequences can occur even due to a slight release of mercury into the atmosphere. If demercurization of the premises is not done on time, then it can be very harmful to health.
Treatment in these cases is usually carried out with the following drugs:
- vitamins;
- antihistamines;
- barbiturates;
- "Aminazine".
Human use
The most common place to use and store metallic mercury is thermometers and thermometers. In one such equipment, up to 3 g of metal can be located. In addition, we can distinguish several more areas of human activity in which mercury is used quite widely:
- medicine (calomel, mercusal, promeran, many antiseptics);
- technical activities - current sources, incandescent lamps, pumps, barometers, detonator and so on;
- metallurgy - spraying mirrors, decorating with gold and silver amalgams, obtaining metal alloys, pure substances;
- chemical industry;
- Agriculture.
Currently, due to the production of safer and more convenient substances, mercury has almost been supplanted from medicine.