What are heavy metals?

What are heavy metals? About chromium, antimony and zinc

Lately there has been a lot of talk about the pollution of nature with heavy metals . This category includes more than 40 chemical elements (tin, tungsten, molybdenum, tellurium, antimony, cadmium, iron, zinc, chromium, mercury, manganese, lead, cobalt, bismuth, nickel, gallium, copper, germanium, thallium).

Calling “heavy metals” “toxic elements” is an inaccurate concept, because they are not the only ones that form toxic compounds for living organisms. Lighter elements can also be dangerous at certain concentrations.

Rocks of igneous and sedimentary origin

The main natural source of heavy metal pollution is various rocks of igneous and sedimentary origin. Many minerals containing these elements may be impurities in other rocks. This group includes: chromium (Fe2Cr2O4) and titanium minerals (anatase, ilmenite, brucite). Compounds of this category of chemical elements can enter the atmosphere from space (with cosmic dust), and from the bowels of our planet (with the help of volcanic gases).

Anthropogenic pollution

An important factor in the release of heavy metals into the environment is anthropogenic pollution . The cement industry, ferrous and non-ferrous metallurgy, due to technological processes at high temperatures, releases very large amounts of these elements into our environment.

These pollutants can also penetrate into our food if the fields were irrigated with water containing a high concentration of such chemical elements (for example, domestic wastewater). This happens because some of them are considered microelements. Of course, this is not the only way these metals end up in water bodies.

If there are metallurgical enterprises, mines near your habitat, or large amounts of mineral fertilizers containing zinc, copper, iron, molybdenum are applied to your fields, then they can get into groundwater due to rain and melting snow.

So I advise you to test the water quality for heavy metal content in the area if you want to dig a well.

Not only local anthropogenic activity can affect the increase in the content of heavy metals in the atmosphere. In the form of aerosols, these chemical elements can be transported many tens, hundreds, and even thousands of kilometers from the place of their release into the atmosphere. Also, heavy elements can accumulate at the bottom of closed reservoirs in sediments.

Part of their content is formed by insoluble carbonates, sulfates, and are also included in mineral and organic sediments. Thus, the content of heavy metals in reservoir sediments increases, but if the sediments are oversaturated with these metals, they will fall back into the water and then there will be a “double whammy.”

Why is that? Yes, because we have not yet felt the global effect of severe pollution with such elements. When these sediments from the bottom of reservoirs lose their ability to bind them, they will “return” parts of these elements back into the water and then we will look for suitable water somewhere else. A particularly difficult situation has arisen near highways.

The soil there has accumulated so much lead, cadmium and zinc that no positive forecasts are expected.

How are heavy metals removed from water and soil?

Heavy metals entering the soil begin to accumulate in the upper layers of this layer. There are sure ways to remove them: consumption by plants, leaching, erosion, removal by water. As a function of the element, the half-life of removal from the soil may vary. For example, reducing the initial concentration to half for certain elements is: for cadmium - 13 - 110 years, for zinc 70 - 510 years, for copper - 310 - 1500 years, for lead - 770 - 5900 years.

The solubility of compounds of these elements in the soil is influenced by various factors:

This is why increased oxygen levels in the aqueous solution are recommended. Oxygen oxidizes metal ions to insoluble forms. Plants are an important link in the cycle of heavy metals in nature. They accumulate them in tissues, from where they can pass to animals and humans.

Everyone knows that several chemical elements from this category are included in the group of trace elements. Plants, each according to their type, concentrate certain microelements.

The toxicity of heavy metals increases with increasing atomic mass. Each such chemical element, at a high level in a living organism, affects certain biochemical processes.

Scientists have recently become interested in the effects of heavy metals on animals. It turns out that they can accumulate them, thus serving as indicators. The most sensitive animals are considered to be soil animals (saprophytes, due to the fact that they live in a certain territory), the European mole, bank vole, elk, and brown bear. Information about mammals is especially interesting, because this way you can more accurately learn about possible effects on humans.

The effect of heavy metals on living organisms

By affecting animal organisms, heavy metals accumulate in tissue and cause various diseases.

Antimony (Sb)

The main sources of pollution with this element are considered to be wastewater from enterprises that produce matches, glass, paints, rubber and the natural process of leaching of antimony minerals (stibiocanite, senarmontite, stibnite, serventite, valentinite).

antimony in natural reservoirs

In natural clean reservoirs, the compounds of this chemical element do not exceed the norm and are in a dispersive state. The presence of compounds of trivalent and pentavalent antimony is possible.

Normal water from the surface of the Earth contains very low concentrations of antimony (less than a microgram per liter of water), in the seas it is contained at a level of 0.5 μg/liter, and in underground waters it is about 10 μg/liter.

Maximum permissible concentration of antimony for the aquatic environment

In natural reservoirs, the maximum permissible concentration of antimony (MAC) is 0.05 mg/liter, and in reservoirs intended for fishing purposes (MAC) - 0.01 mg/liter.

Chromium (Cr)

Basically, compounds of tri- and hexavalent this element enter surface waters by leaching of various minerals (crocoite, chromite, uvarovite). Other natural sources of chromium include plants and other living organisms. The decomposition of these living organisms may release Cr ions. Humans can also be involved in polluting the environment with its compounds. The most important sources of chromium contamination are:

A decrease in the concentration of Cr in water is observed due to adsorption on the surface of rocks and processing by various organisms.

The level of Cr compounds in water depends on many factors such as:

It is very important what sorbents are in silt, sediments at the bottom of reservoirs (calcium carbonate, clay, iron hydroxide, plant and animal remains) because they affect the overall level of chromium in the water. Soluble forms of Cr are chromates and dichromates. At increased oxygen concentrations in water (aerobic conditions), hexavalent chromium salts Cr(VI) transform into trivalent chromium salts Cr(III), which at elevated pH transform into insoluble hydroxides.

The concentration of Cr in clean, unpolluted waters ranges from 0.1 µg/liter to n*1 µg/liter, in polluted waters - from n*10 µg/liter to n*100 µg/liter. In the seas, Cr is contained at a level of 0.05 μg/liter, and in underground waters from n*10 to n*100 μg/liter.

It is important to know that hexavalent and trivalent chromium compounds at high concentrations in the environment can cause cancer in animals and humans living in this environment.

Maximum permissible concentration of chromium for the aquatic environment

The maximum permissible concentration for Cr(VI) in reservoirs should not exceed 0.05 mg/liter, and for Cr(III) - 0.5 mg/liter.

In fishery reservoirs, the content of hexavalent chromium MAC fisheries should not exceed 0.001 mg/liter, and trivalent chromium - 0.005 mg/liter.

Zinc (Zn)

The main minerals and rocks that can serve as natural zinc contaminants are sphalerite, smithsonite, calamine, goslarite, and zincite. Anthropogenic factors of zinc pollution can be wastewater from various industrial facilities (factories for the production of mineral paints, parchment paper, viscose fiber and electroplating shops).

In water, Zn is found in ionic form, as well as in the form of organic and mineral complexes. The most common forms of insoluble zinc compounds are carbonates, sulfides, and hydroxides.

zinc in natural reservoirs

In the seas, Zn is contained in concentrations from 1.5 to 10 μg/liter, and in rivers - 3 to 120 μg/liter. Waste water from mines and mines, at low pH, can contain very high levels of zinc.

Zn is one of the most important microelements that all plants and animals need. There are also negative aspects of zinc; the chloride and sulfate of this element are toxic.

Maximum permissible concentration of zinc for the aquatic environment

The maximum permissible concentration for zinc in natural reservoirs is 1 mg Zn2+/liter, and in fishery reservoirs the maximum permissible concentration for zinc is 0.01 mg Zn2+/liter.

Source: https://www.net-bolezniam.ru/chto-takoe-tjazhelye-metally-pro-hrom-surmu-i-cink/61/

Non-ferrous metals - what are they? Classification and their properties:

All existing metals are divided into ferrous and non-ferrous. The first category includes iron and alloys based on it. In the modern world, non-ferrous metals are the most valuable materials used in production. Due to their advantages, they are widely used in those industries where a high degree of resistance to aggressive environmental conditions is extremely important.

Concept

Non-ferrous metals are substances that do not contain iron. They are usually used in the form of alloys. Due to their properties, they are very popular in leading industries: mechanical engineering, rocket, aviation, medical, electronics, instrument making, etc.

Non-ferrous metals are often various types of rolled products intended for subsequent production of products. Contrary to their name, they do not always have bright shades and a sparkling shine. However, all non-ferrous metals are valuable materials.

There is no clear classification; most often they are conditionally divided into the following groups:

• heavy;
• lungs;
• small;
• alloying;
• noble;
• rare.

Each group contains many names of substances that have different costs. For example, at a non-ferrous metal collection point, a kilogram of copper scrap is bought for an average of 300 rubles, and silver - 7-30 thousand rubles (depending on its category).

Extraction and processing

Obtaining valuable substances is a labor-intensive and economically expensive process. Their content in the earth's crust is insignificant and in their pure form they are extremely rare.

After mining, the ore is sent to a non-ferrous metals plant for processing. Despite the complexity of the beneficiation processes and subsequent production of blanks, in a number of properties all types of non-iron materials have no analogues, which explains their popularity.

The method of processing non-ferrous metals depends on the substance from which they are composed. The main technologies include:

• pressing;
• punching;
• rolling;
• drawing;
• forging.

Properties

Non-ferrous metals are substances that have valuable benefits:

• high degree of thermal conductivity;
• low density;
• low melting point;
• corrosion resistance.

Depending on the type of alloy, the values ​​of the indicators differ, however, these properties are very important in the production processes of leading industries.

Heavy non-ferrous metals

This group includes:

• copper,
• lead,
• zinc,
• nickel,
• tin.

Copper is a golden-pink metal with a high ductility rate. Its main property is electrical conductivity, due to which it is used mainly in instrument making and radio electronics. In addition, copper has remarkable corrosion resistance and is easy to process. In combination with zinc it forms brass, and with other elements it forms bronze.

Lead is a toxic, gray metal. Despite its properties, it is extremely in demand in the automotive, weapons and medical industries. Lead has a low melting point (327°C), it is malleable and can be easily rolled into thin sheets. Its compounds are added to fuel to improve the quality characteristics of the latter, but at the same time, during vehicle operation, exhaust gases significantly pollute the environment.

Zinc in its pure form is a blue-white metal. When interacting with air, its surface becomes dull due to the appearance of an oxide film. In terms of volume of use in leading industries, zinc ranks 4th.

Nickel is a silvery-white metal. Plastic, which simplifies the processing process. Is ferromagnetic. Often, nickel is used in the form of alloys with steel, iron, chromium, gold, silver, magnesium, etc. In its pure form, it serves as a material for the manufacture of pipes, sheets, spirals, etc.

Tin is a white or gray metal that darkens as it turns into a powder. It has a low melting point (232°C) and good ductility even when cold. In combination with bismuth and cadmium, tin is used to produce reliable fasteners.

Light non-ferrous metals

Examples of substances belonging to this group:

Aluminum is the leader in mining and production volumes throughout the world. It has high electrical conductivity, which decreases due to the addition of various impurities. Difficult to weld, but easy to process in other ways.

Aluminum alloys are widely used in the aviation, rocket, mechanical engineering, and chemical industries. The characteristics of the material, combined with its low cost, make it one of the most popular.

For example, at a non-ferrous metals collection point, a kilogram of aluminum is bought for 35–90 rubles.

Magnesium is a silvery-white substance. The oxide film of the metal is quite resistant to aggressive environmental influences; its destruction occurs when heated to 600°C. At the same temperature, magnesium burns at an astonishing rate. It is mainly used in the military industry and in the production of pyrotechnic products. In the form of alloys - in the automotive and aviation industries.

Titanium is a very refractory substance with increased strength and resistance to deformation. Its peculiarity is its paramagnetic property. In its pure form it is used for the manufacture of various workpieces, in the form of alloys - for the production of parts and mechanisms of increased strength and wear resistance.

Small non-ferrous metals

These include:

Antimony is a silvery-white metal with a bluish tint. An extremely fragile substance that can be crushed even with your fingers. It is used in the form of alloys, significantly increasing the hardness of the metal connected to it. In addition to industrial use, antimony is also popular in the medical industry - it is effective for treating inflammatory diseases of the mucous membrane of the eyes.

Mercury is a metal that has a liquid state of aggregation. It has been used for many years in the medical industry (thermometers) and advanced technologies (position sensors, ion engines).

Cadmium is a white substance with a bright metallic luster. Along with increased hardness, it is easy to cut with a knife. Its properties are similar to mercury and zinc. In its pure form, it is poisonous to any living beings.

Alloying non-ferrous metals

Examples of substances in this group are:

• tungsten,
• molybdenum,
• vanadium,
• cobalt.

Tungsten is a silvery-white metal that resembles platinum in appearance. It is one of the most refractory and dense substances. It is used in the production of cutting tools (including medical ones), ammunition, jewelry, aircraft and missile parts.

Molybdenum is a soft, silvery substance that is not found in nature in its pure form. In terms of strength, it is slightly inferior to tungsten, but is easier to process. It is mainly used in the aviation and missile industries.

Vanadium is a silvery-white metal characterized by high ductility. It is rarely used in its pure form; its main purpose is to increase corrosion resistance and improve the mechanical properties of steel used in the automotive industry.

Cobalt is a silvery substance with a yellowish or bluish tint. Alloys based on it are used for the production of tools and parts of medical equipment.

Noble non-ferrous metals

These include:

Gold is a chemically resistant metal. The oxidation process does not start even when it is molten. Only a mixture of hydrochloric and nitric acids (“regia vodka”) can dissolve metal. It has high viscous properties and is easy to process. On the non-ferrous metals exchange, gold is highly valued - the price for 1 gram is 2,450 rubles.

Silver is a malleable and ductile metal. It has very high thermal and electrical conductivity. Despite its ductility, it is very refractory. Does not oxidize under the influence of oxygen.

Platinum is valued above all else among jewelers and is used in its pure form. It has excellent anti-corrosion properties and high resistance to any chemicals and deformations. At the collection point for non-ferrous metals, 1 gram of platinum scrap is bought for 1,600 rubles.

Rare non-ferrous metals

Examples of substances included in this group:

Niobium is a gray metal with a bright steely sheen. It has paramagnetic properties and has a very high refractoriness index. Widely used in the aviation industry and radio engineering.

Tantalum is a silver-colored substance with high hardness and density. Despite this, it is easy to process. Used in the metallurgical, chemical and nuclear industries.

Finally

Both ferrous and non-ferrous metals are extremely popular materials. They are widely used in most industries: mechanical engineering, aviation, missile, nuclear, military, construction, medical, metallurgical, jewelry, instrument-making, electrical, chemical, etc. At the same time, non-ferrous metals are valued higher due to their properties.

Source: https://www.syl.ru/article/339228/tsvetnyie-metallyi---eto-kakie-klassifikatsiya-i-ih-svoystva

The heaviest metals in the world

Humanity began to actively use metals back in 3000-4000 BC. Then people became acquainted with the most common of them: gold, silver, copper. These metals were very easy to find on the surface of the earth. A little later they learned about chemistry and began to isolate such species as tin, lead and iron. In the Middle Ages, very poisonous types of metals gained popularity.

There was arsenic in use, which poisoned more than half of the royal court in France. So did mercury, which helped cure various diseases of those times, from sore throat to the plague. Already before the twentieth century, more than 60 metals were known, and at the beginning of the 21st century - 90. Progress does not stand still and leads humanity forward.

But the question arises, which metal is heavy and weighs more than all the others? And in general, what are they, these heaviest metals in the world?

Many people mistakenly think that gold and lead are the heaviest metals. Why exactly did this happen? Many of us grew up watching old movies and seeing the main character using a lead plate to protect himself from vicious bullets. In addition, lead plates are still used today in some types of body armor. And when you hear the word gold, many people think of a picture of heavy ingots of this metal. But thinking that they are the heaviest is a mistake!

To determine the heaviest metal, one must take into account its density, because the higher the density of a substance, the heavier it is.

TOP 10 heaviest metals in the world

1. Osmium (22.62 g/cm3),
2. Iridium (22.53 g/cm3),
3. Platinum (21.44 g/cm3),
4. Rhenium (21.01 g/cm3),
5. Neptunium (20.48 g/cm3),
6. Plutonium (19.85 g/cm3),
7. Gold (19.85 g/cm3)
8. Tungsten (19.21 g/cm3),
9. Uranium (18.92 g/cm3),
10. Tantalum (16.64 g/cm3).

And where is the lead? And he is located much lower on this list, in the middle of the second ten.

Osmium and iridium are the heaviest metals in the world

Let's look at the main heavyweights who share 1st and 2nd places. Let's start with iridium and at the same time say words of gratitude to the English scientist Smithson Tennat, who in 1803 obtained this chemical element from platinum, where it was present along with osmium as an impurity. Iridium can be translated from ancient Greek as “rainbow”.

The metal is white with a silver tint and can be called not only the heaviest, but also the most durable. There is very little of it on our planet and only up to 10,000 kg are mined per year. It is known that most iridium deposits can be found at meteorite impact sites.

Some scientists come to the conclusion that this metal was previously widespread on our planet, but due to its weight, it constantly squeezed itself closer to the center of the Earth. Iridium is now widely in demand in industry and is used to generate electrical energy.

Paleontologists also like to use it, and with the help of iridium they determine the age of many finds. In addition, this metal can be used to coat some surfaces. But this is difficult to do.

Iridium

Next, let's look at osmium. It is the heaviest in the periodic table of Mendeleev, and, accordingly, the heaviest metal in the world. Osmium is tin-white with a blue tint and was also discovered by Smithson Tennat at the same time as iridium.

Osmium is almost impossible to process and is mainly found at meteorite impact sites. It smells unpleasant, the smell is like a mixture of chlorine and garlic. And from ancient Greek it is translated as “smell”. The metal is quite refractory and is used in light bulbs and other devices with refractory metals.

For just one gram of this element you have to pay more than $10,000, which makes it clear that the metal is very rare.

Osmium

Whatever one may say, the heaviest metals are very rare and therefore they are expensive. And we must remember for the future that neither gold nor lead are the heaviest metals in the world! Iridium and osmium are the winners in weight!

Source: http://www.alto-lab.ru/elements/samye-tyazhelye-metally-v-mire/

What are the types and types of metals and their alloys?

In construction, industry and other areas of human life, various types of metals are often used. They differ from each other in the properties by which they are selected and used in a particular area. Materials are obtained in a variety of ways. Certain types of metals are combined together to create alloys that have unique physical and chemical properties.

Characteristics and Signs

Metals are a group of elements in the form of simple substances that have characteristic metallic properties. In nature they are present in the form of ores or compounds. Sciences such as chemistry, physics and metallurgy study the characteristics of these materials.

Metals have a combination of different properties. Mechanical factors determine their ability to resist deformation and destruction. Technological methods help determine the ductility of materials to various types of processing. Chemical properties show their interaction with different substances, and physical properties indicate their behavior in thermal, gravitational or electromagnetic fields.

Metals are classified according to the following properties:

• Hardness is the resistance of a material to penetration by another.
• Strength - preservation of shape, structure and size after exposure to dynamic, static and alternating loads.
• Elasticity is a change in shape without violating integrity during deformation and the possibility of returning to its original form.
• Plasticity is the retention of the resulting shape and integrity under the influence of forces.
• Wear resistance - maintaining external and internal integrity under the influence of prolonged friction.
• Viscosity - maintaining integrity under increasing physical stress.
• Fatigue is the number and period of cyclic impacts that a metal can withstand without changing its integrity.
• Heat resistance - resistance to high temperatures.

The primary characteristic of metals is the negative conductivity coefficient of electricity, which increases when the temperature drops, and is partially or completely lost when the temperature rises. Secondary characteristics of materials are metallic luster and high melting point. In addition, some types of metal compounds can be reducing agents in redox reactions.

Metallic properties are interrelated, since the components of the material affect all other parameters. Metals are divided into ferrous and non-ferrous, but they are classified according to many criteria.

Group with iron and its alloys

Ferrous metals are characterized by impressive density, high melting point and dark gray color. This group mainly includes iron and its alloys. To impart specific properties to the latter, alloying components are used.

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Subgroups of ferrous metals:

• Iron - iron, cobalt, manganese, nickel. They are usually taken as a base or as an additive to alloys.
• Refractory - tungsten, molybdenum, titanium, chromium. They melt at a temperature higher than the melting level of iron. Alloy steels are obtained from refractory varieties.
• Rare earths - lanthanum, neodymium, cerium. They have related chemical properties, but differ in physical parameters. Used as an additive to alloys.
• Uranium (actinides) - actinium, neptunium, plutonium, thorium, uranium. Widely used in nuclear energy.
• Alkaline earths - calcium, lithium, sodium. They are not used in free form.

Metals of the ferrous group are represented by iron alloys with different carbon content and the content of additional chemical elements: silicon, sulfur or phosphorus. Popular materials are steel and cast iron. Steel contains up to 2% carbon.

It is characterized by good ductility and high technological performance. In cast iron, the carbon content can reach 5%.

The properties of the alloy may differ with different chemical elements: with the content of sulfur and phosphorus, brittleness increases, and with chromium and nickel, cast iron becomes resistant to high temperatures and corrosion.

Colored varieties

Non-ferrous metals are more in demand than ferrous metals, since most of them are raw materials for the production of rolled metal. This group of materials has a wide range of applications: they are used in metallurgy, mechanical engineering, radio electronics, high technology and other fields.

Classification by physical parameters:

• Heavy - cadmium, nickel, tin, mercury, lead, zinc. Under natural conditions, they are formed in strong compounds.
• Lightweight - aluminum, magnesium, strontium, titanium and others. Characterized by a low melting point.
• Noble ones - gold, platinum, rhodium, silver. They are characterized by increased resistance to corrosion.

Non-ferrous metals are characterized by low density, good ductility, low melting point and predominant colors (white, yellow, red). Various equipment is made from them. Since the strength of the materials is quite low, they are not used in their pure form. Light alloys for various purposes are produced from them.

Materials of this group are characterized by impressive atomic weight and density, exceeding that of iron.

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Copper, which acts as a conductor of electric current, is in great demand.

It is characterized by a pinkish-red hue, low resistivity, good thermal conductivity, low density, excellent ductility and corrosion resistance. In the technical field, copper alloys are used: bronze (with the addition of aluminum, nickel or tin) and brass (with zinc).

Bronze is used in the production of membranes, round and flat springs, worm gears and various fittings. Tapes, sheets, wire, pipes, bushings, and bearings are made from brass.

The group of heavy metals is one of the main causes of environmental pollution. Toxic substances enter the oceans through wastewater from industrial plants. Some varieties of the heavy group can accumulate in living organisms.

Mercury is a highly toxic metal for humans. When coal is burned at power plants, its compounds pass into the atmosphere, and then are converted into sediment and end up in water bodies. Inhabitants of freshwater and marine systems accumulate large amounts of a dangerous substance, which leads to poisoning or death of people.

Cadmium is considered a trace element and a fairly rare element that can enter the ocean through wastewater from metallurgical plants. This substance is present in small quantities in the human body, but at high levels it destroys bone tissue and leads to anemia.

Lead is present in a dispersed state almost everywhere. When there is an excess of metal in the human body, health problems are observed.

Soft types

Silver-white aluminum is characterized by lightness, high corrosion resistance, good electrical conductivity and ductility. The characteristics of the material have made it useful in aircraft construction, the electrical industry and food production. Aluminum alloys are used in mechanical engineering.

Magnesium has low corrosion resistance, but the lightweight material is indispensable in the technical field. Alloys with this metal use aluminum, manganese and zinc, which are easy to cut and have high strength. Magnesium alloys are used in the production of cases for cameras, engines and other devices.

Titanium is used in mechanical engineering, the rocket industry and the chemical industry. Alloys containing this substance are characterized by low density, excellent mechanical properties, corrosion resistance and flexibility in pressure treatment.

Noble materials

Some types of metals are rarely found in nature and require labor-intensive extraction methods. The noble group metals are:

• Gold.
• Silver.
• Platinum.
• Rhodium.

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People learned about gold back in the Stone Age. The most expensive metal in the world can be found in nature in the form of nuggets, which contain a small amount of impurities. It is also found in alloys with silver.

Gold has thermal conductivity and very low resistance. Due to its good malleability, the material is used in the manufacture of jewelry.

Silver comes second in value after gold. In nature, it is usually found as silver ore. Silver is characterized by softness, ductility, thermal and electrical conductivity.

Platinum, discovered in the mid-20th century, is a rare material that can only be found in deposits of various alloys. It is quite difficult to obtain. The value of the metal lies in the fact that it is not affected by acids. When heated, platinum does not change color and does not oxidize.

Rhodium is also a noble metal. It has a silver color with a blue tint. Rhodium is resistant to chemical influences and temperature changes, but the fragile metal deteriorates under mechanical stress.

Hardness classification

Metals are also divided into hard and soft.

The hardest pure material in the world is chromium . It belongs to the refractory varieties and lends itself well to mechanical processing. Another solid element is tungsten.

It is characterized by high melting point, heat resistance and flexibility. Various parts are forged from it and small elements necessary for lighting fixtures are made. Tungsten is often present in heavy alloys.

Hard metals are not only difficult to mine, but also difficult to find on the planet. They are mainly found in meteorites that fell to Earth.

The softest metals include potassium, sodium, rubidium and cesium. Also in this group are gold, silver, copper and aluminum. Gold is present in marine complexes, granite fragments and the human body. External factors can destroy valuable metal.

Soft silver is used in the manufacture of dishes and jewelry. Sodium is widely used in almost every industrial sector.

Mercury, the softest metal in the world, is used in the agricultural and chemical industries, as well as electrical engineering.

Source: https://vtothod.ru/klassy/kakie-byvayut-vidy-i-tipy-metallov-i-ih-splavov

Non-ferrous metals: list, names, classification and use:

The leading industry in the economy of our country is metallurgy. For its successful development, a lot of metal is needed. This article will discuss non-ferrous heavy and light metals and their use.

Classification of non-ferrous metals

Depending on their physical properties and purpose, they are divided into the following groups:

• Light non-ferrous metals. The list of this group is large: it includes calcium, strontium, cesium, potassium, and lithium. But the most commonly used metals in the metallurgical industry are aluminum, titanium and magnesium.
• Heavy metals are very popular. These are the well-known zinc and tin, copper and lead, as well as nickel.

• Noble metals such as platinum, ruthenium, palladium, osmium, rhodium. Gold and silver are widely used to make jewelry.
• Rare earth metals - selenium and zirconium, germanium and lanthanum, neodymium, terbium, samarium and others.
• Refractory metals - vanadium and tungsten, tantalum and molybdenum, chromium and manganese.
• Minor metals such as bismuth, cobalt, arsenic, cadmium, mercury.
• Alloys – brass and bronze.

Light metals

They are widespread in nature. These metals have low density. They have high chemical activity. They are strong connections. The metallurgy of these metals began to develop in the nineteenth century. They are obtained by electrolysis of molten salts, electrothermy and metallothermy. Light non-ferrous metals, the list of which has many items, are used for the production of alloys.

Aluminum

Refers to light metals. It has a silvery color and a melting point of about seven hundred degrees. In industrial conditions it is used in alloys. It is used wherever metal is needed. Aluminum has low density and high strength. This metal is easy to cut, saw, weld, drill, solder and bend.

Alloys are formed with metals of various properties, such as copper, nickel, magnesium, silicon. They are highly durable and do not rust in adverse weather conditions. Aluminum has high electrical and thermal conductivity.

Magnesium

It belongs to the group of light non-ferrous metals. It has a silver-white color and a film oxide coating. It has a low density and is easy to process. The metal is resistant to flammable substances: gasoline, kerosene, mineral oils, but is susceptible to dissolution in acids. Magnesium is not magnetic. It has low elastic and casting properties and is susceptible to corrosion.

Titanium

This is a light metal. It is not magnetic. It has a silver color with a bluish tint. It has high strength and corrosion resistance. But titanium has low electrical and thermal conductivity. Loses mechanical properties at a temperature of 400 degrees, becomes brittle at 540 degrees.

The mechanical properties of titanium are enhanced in alloys with molybdenum, manganese, aluminum, chromium and others. Depending on the alloying metal, alloys have different strengths, including high-strength ones. Such alloys are used in aircraft construction, mechanical engineering, and shipbuilding. They are used to produce rocketry, household appliances and much more.

Heavy metals

Heavy non-ferrous metals, the list of which is very wide, are obtained from sulfide and oxidized polymetallic ores. Depending on their types, methods for obtaining metals differ in the method and complexity of production, during which the valuable components of the raw material must be completely extracted.

Metals in this group are hydrometallurgical and pyrometallurgical. Metals obtained by any method are called rough. They undergo a refining procedure. Only after this can they be used for industrial purposes.

Copper

Non-ferrous metals, the list of which is presented above, are not all used in industry. In this case we are talking about a common heavy metal – copper. It has high thermal conductivity, electrical conductivity and ductility.

Copper alloys are widely used in industries such as mechanical engineering, and all due to the fact that this heavy metal is well alloyed with others.

Zinc

It also represents non-ferrous metals. The list of names is large. However, not all heavy non-ferrous metals, which include zinc, are used in industry. This metal is fragile. But if you heat it to one hundred and fifty degrees, it will be forged without problems and rolled with ease. Zinc has high anti-corrosion properties, but it is susceptible to destruction when exposed to alkali and acid.

Lead

The list of non-ferrous metals would be incomplete without lead. It is gray in color with a hint of blue. The melting point is three hundred twenty-seven degrees. It is heavy and soft. It is hammer forged well and does not harden. It is poured into various shapes. Resistant to acids: hydrochloric, sulfuric, acetic, nitric.

Brass

These are alloys of copper and zinc with the addition of manganese, lead, aluminum and other metals. The cost of brass is less than copper, but its strength, toughness and corrosion resistance are higher. Brass has good casting properties. Parts are produced from it by stamping, rolling, drawing, and rolling. This metal is used to make shell casings and much more.

Use of non-ferrous metals

Not only the metals themselves, but also their alloys are called non-ferrous. The exception is the so-called “ferrous metal”: iron and, accordingly, its alloys. In European countries, non-ferrous metals are called non-ferrous metals.

Non-ferrous metals, the list of which is quite large, have found wide application in various industries all over the world, including in Russia, where they are the main specialization. They are produced and mined in all regions of the country.

Light and heavy non-ferrous metals, the list of which is represented by a wide variety of items, constitute a branch of industry called “Metallurgy”. This concept includes the extraction, enrichment of ores, and smelting of both metals and their alloys.

Currently, the non-ferrous metallurgy industry has become widespread. The quality of non-ferrous metals is very high, they are durable and practical, and are used in the construction industry: they are used to decorate buildings and structures. They are used to produce profile metal, wire, tapes, strips, foil, sheets, and rods of various shapes.

Source: https://BusinessMan.ru/tsvetnyie-metallyi-spisok-nazvaniya-klassifikatsiya-i-ispolzovanie.html

List of heavy metals: types and features

Of all 104 chemical elements known to mankind today, 82 are metals. They occupy a prominent place in the lives of people in the industrial, biological and environmental spheres. Modern science divides metals into heavy, light and noble. In this article we will look at the list of heavy metals and their features.

Determination of heavy metals

Initially, it was customary to call heavy metals those representatives that have an atomic mass above 50. However, the use of this term today occurs more often not from a chemical point of view, but depending on their impact on environmental pollution. Thus, the list of heavy metals includes those metals and metalloids (semi-metals) that pollute elements of the human biosphere (soil, water). Let's look at them.

How many elements does the list of heavy metals include?

Today there is no consensus on the number of elements in this list, since there are no general criteria classifying metals as heavy. However, the list of heavy metals can be formed depending on the various properties of the metals and their characteristics. These include:

• Atomic weight. Based on this criterion, these include more than 40 elements with an atomic mass exceeding 50 amu (g/mol).
• Density. Based on this criterion, those metals whose density is equal to or exceeds that of iron are considered heavy.
• Biological toxicity combines heavy metals that negatively affect the life of humans and living organisms. There are about 20 elements in their list.

Effect on the human body

Most of these substances have a negative effect on all living organisms. Due to their significant atomic mass, they are poorly transported and accumulate in human tissues, causing various diseases. Thus, for the human body, cadmium, mercury and lead are recognized as the most dangerous and heaviest metals.

The list of toxic elements is grouped by degree of danger according to the so-called Mertz rules, according to which the most toxic metals have the smallest exposure range:

1. Cadmium, mercury, thallium, lead, arsenic (a group of the most dangerous metal poisons, exceeding permissible limits can lead to serious psycho-physiological disorders and even death).
2. Cobalt, chromium, molybdenum, nickel, antimony, scandium, zinc.
3. Barium, manganese, strontium, vanadium, tungsten

This does not mean, however, that none of the elements grouped above, according to Mertz's rules, should be present in the human body. On the contrary, the list of heavy metals includes these and more than 20 other elements, a small concentration of which is not only not dangerous for human life, but is also necessary in metabolic processes, especially iron, copper, cobalt, molybdenum and even zinc.

Environmental pollution with heavy metals

Elements of the biosphere that are polluted by heavy metals are soil and water. Most often, the culprits for this are metallurgical enterprises that process light and heavy non-ferrous metals. The list of polluting agents also includes waste incineration plants, automobile exhausts, boiler houses, chemical production companies, printing companies, and even power plants.

The most common toxins are: lead (automotive production), mercury (example of distribution: thermometers broken in everyday life and fluorescent lighting fixtures), cadmium (formed as a result of burning garbage). In addition, most factories in production use one or another element that can be characterized as heavy. The metal group, the list of which was given above, most often enters water bodies in the form of waste and then reaches humans along the trophic chain.

In addition to man-made factors of pollution of nature with heavy metals, there are also natural ones - these are volcanic eruptions, in the lava of which an increased content of cadmium was found.

Features of the distribution of the most toxic metals in nature

Mercury in nature is most localized in water and air. Mercury enters the waters of the world's oceans from industrial drains, and mercury vapors formed as a result of coal combustion are also found. Toxic compounds accumulate in living organisms, especially in seafood.

Lead has a wide distribution area. It accumulates in the mountains, and in the soil, and in water, and in living organisms, and even in the air, in the form of exhaust gases from cars. Of course, lead also enters the environment as a result of anthropological action in the form of industrial waste and non-recycled waste (accumulators and batteries).

And the source of environmental pollution with cadmium is wastewater from industrial enterprises, as well as natural factors: weathering of copper ores, soil leaching, as well as the results of volcanic activity.

Scope of application of heavy metals

Despite the toxicity, modern industry creates a huge variety of useful products by processing heavy non-ferrous metals, the list of which includes alloys of copper, zinc, lead, tin, nickel, titanium, zirconium, molybdenum, etc.

Copper is a highly plastic material that is used to make a variety of wires, pipes, kitchen utensils, jewelry, roofing and much more. In addition, it is widely used in mechanical engineering and shipbuilding.

Zinc has high anti-corrosion properties, so the use of zinc alloys for coating metal products (so-called galvanizing) is common. Areas of application for zinc products: construction, mechanical engineering, printing (production of printed forms), rocket science, chemical industry (production of varnishes and paints) and even medicine (antiseptics, etc.).

Lead melts easily, so it is used as a raw material in many industries: paint and varnish, chemical, automotive (part of batteries), radio electronics, medical (production of protective aprons for patients during X-ray examinations).

Source: https://FB.ru/article/300068/spisok-tyajelyih-metallov-vidyi-i-osobennosti

The heaviest metal in the world: list of TOP 10 elements in the periodic table by density

Hello, friends!

Did you know that initially the periodic table contained a zero group, in which ether stood along with the inert gases?
Although that’s not what we’re talking about today. 10 million dollars - this is the amount that 1 gram of the rarest metal in the world, California, is valued at. The second place in rarity, and therefore in price, is occupied by osmium.

In addition, it is also the heaviest metal in the world, although some scientists believe that this position should be occupied by iridium.

Which metal is the heaviest?

To determine which is heavier, you need to compare atomic weights and see which has a higher density. According to these indicators, osmium and iridium, which is inferior to it by fractions of cubic centimeters, are considered the heaviest today. Imagine: an osmium cube with eight-centimeter sides weighs almost 12 kg!

I suggest you look at the photo of the heaviest metal:

And this is iridium:

Handsome, aren't they?

Top 10 heaviest metals in the world

I suggest you familiarize yourself with the elements according to their rating.

Tantalum

Considered a rare and not very heavy metal, it has a density of 16.65 g/cm³. It is used by surgeons - it is practically indestructible and rust-proof, and is easy to process.

Uranus

The density of uranium is 19.07 g/cm³. Its main difference from its counterparts is natural radioactivity. During the transformation process that uranium atoms undergo, the substance turns into another radiating element. The chain of transformations consists of 14 stages, one of them is the transformation into radium, the last stage is the formation of lead. True, it will take more than one billion years for the complete transition of uranium to lead.

Tungsten

Tungsten (19.25 g/cm³) is jokingly called an ideal candidate for counterfeiting gold bars. This is the most refractory material, the melting point is close to the photosphere of the Sun - 3422 °C. Therefore, it is best suited for filaments in incandescent lamps.

Gold

Gold density is 19.3 g/cm³. Soft, viscous, with good thermal and electrical conductivity, it is not afraid of chemical attack. Gold is not only found on the surface of the Earth. 5 times more of it is contained in the planet's core.

Plutonium

This element is one of the stages of radioactive transformation of uranium. It also exists in the depths of the planet, but in minute quantities. Its density is 19.7 g/cm³. Due to its radioactivity, plutonium is always warm and is a poor conductor of current and heat.

Neptunium

This is another creation of uranium, obtained through nuclear reactions. Density – 20.25 grams per cubic centimeter. Neptunium is a fairly soft and malleable material that reacts slowly with air and water.

Rhenium

Rhenium is another refractory, malleable, oxidation-resistant element. Melting point – 2000 °C. In total, the world's reserves of the element are approximately 17,000 tons. Rhenium density is 21.03 g/cm³. It is used in medicine, jewelry, vacuum technology, electronic devices and metallurgy.

Platinum

Platinum, although not the heaviest metal, is quite close to this - 21.45 g/cm³. It is used not only by jewelers, but also by surgeons, investment professionals, the chemical and glass industries, automotive, biomedicine and electronics. Platinum is extremely durable and products made from it are difficult to scratch. This element is found 30 times less frequently than gold.

Osmium

Density 22.6 g/cm³ - the heaviest metal in the world, it is hard, but quite brittle. No matter how much you heat it, it will not lose its shine and gray-bluish tint under any circumstances. It is difficult to process and mainly occurs in meteorite impact areas.

Iridium

The difference between iridium and osmium in density is in hundredths of a gram. Iridium is refractory and is considered rare and precious. Does not interact with acids, air and water. It is used to control welding seams, and in paleontology and geology it is used as an indicator of the layer formed after the fall of a meteorite.

Characteristics of the densest metal

Scientists agreed that, despite almost the same density, iridium is only slightly inferior to the heaviest metal. However, the physicochemical properties of these two elements have not yet been fully studied.

The rarity and labor-intensive nature of extraction determine the cost of osmium - on average, $15,000 per gram. It is included in the platinum group and is conventionally considered noble, but the name of the metal contradicts its status: in Greek “osme” means “smell”. Due to its high chemical activity, osmium smells like a mixture of garlic or radish with chlorine.

The melting point of the heaviest metal is 3033 °C, and it boils at 5012 °C.

Solidifying from the melt, osmium forms beautiful crystals with an interesting blue or silver-blue tint. But, despite its beauty, it is not suitable for making precious accessories, since it does not have the properties necessary for jewelers: malleability and plasticity.

The element is valuable only because of its special strength. Alloys to which very small doses of the heaviest metal are added become incredibly wear-resistant. Usually it is used to cover units that are subject to constant friction.

History of discovery

The years 1803-1804 became a turning point for the heaviest metal: it was at this time that its discovery took place practically under competition conditions.

First, the English chemist Smithson Tennant and his assistant William Hyde Wollaston, who made more than one important discovery, discovered an unusual sediment with a characteristic odor during an experiment with platinum ores and nitric and hydrochloric acids and shared their discovery with others.

Then the French scientists Antoine de Fourcroy and Louis-Nicolas Vauquelin took over the baton and, based on previous and their own research, announced the discovery of a new element. The name was given to it “pten”, which means “flying”, since as a result of the experiments they received flying black smoke.

However, Tennant did not sleep either: he continued his research and did not lose sight of the experiments of the French. As a result, Smithson achieved more concrete results and, in an official document sent to the Royal Society of London, indicated that he had divided pten into two related elements: iridium (“rainbow”) and osmium (“smell”).

Where is it used?

The list of areas of application is quite extensive: aviation, military and missile technology, aerospace industry, medicine. Although weapons manufacturers are already thinking about what can replace the heaviest metal in the world, since osmium is too difficult to process.

Almost half of the world's reserves of the heaviest metal are devoted to the needs of the chemical industry. It is used to stain living tissues under a microscope, ensuring their preservation. In addition, it is used as a dye when painting porcelain.

Isotopes of the heaviest metal are used to make containers for storing nuclear waste.

This element is also used to make elite “eternal” fountain pens and Rolex watches.

Places of natural occurrence

It is almost impossible to detect osmium in its pure form. This heavy element is usually found in combination with iridium. The substance is contained in deposits of platinum ores and at the crash site or in the meteorites themselves that hit the Earth.

Conclusion

Do you agree that physics and chemistry outside the school curriculum are incredibly interesting? Continuing the topic, watch the video about the heaviest metal:

Source: https://zhazhdazolota.ru/interesnoe/samyj-tyazhelyj-metall

Heavy metals

Today, about 40 different interpretations of the term “heavy metals” are known, and it is absolutely impossible to single out the most correct one. Thus, each definition of heavy metals will include its own list of elements in accordance with certain criteria.

Often, the characteristics of heavy metals are based on: atomic mass, density, toxicity, prevalence in the natural environment, degree of involvement in natural and man-made cycles. For example, the main criterion may be a minimum relative atomic mass of 50. According to this feature, absolutely all metals, starting with vanadium, will fall under the list of “heavy metals,” regardless of their density.

However, in other definitions of this term, density is the main characteristic on the basis of which the list is compiled, and it must be more than or equal to 8 g/cm3 (iron density). According to this criterion, the following elements will be included in the list of “heavy metals”: ​​lead, mercury, copper, cadmium, cobalt, but tin will already be excluded from this list, as it is lighter.

In addition, the classification of metals may also be based on other values ​​of threshold density (for example, 5 g/cm3) or atomic mass. Thus, some groups of heavy metals may include elements that are brittle or metalloids (for example, bismuth or arsenic, respectively). In this regard, the term “heavy metals” is considered from a medical and environmental point of view.

This allows the compilation of a list of heavy metals to be based not only on the physical and chemical properties of the element, but also on its biological activity, toxicity, as well as the volume of its use in economic activities.

However, in most cases, the list of heavy metals includes 40 elements with a relative density exceeding 6. Despite the fact that the terms “heavy metals” and “toxic metals” are considered synonymous, the number of hazardous metals is still significantly less , which cannot but rejoice.

Of primary interest are the elements that have the widest and most active use in production, as a result of which they accumulate in the environment, which poses a danger to human health in terms of their biological activity and toxicity. Among these are lead, mercury, cadmium, zinc, bismuth, cobalt, nickel, copper, tin, antimony, vanadium, manganese, chromium, molybdenum and arsenic.

Properties of heavy metals

Heavy metals in the atmosphere are organic and inorganic compounds. They may be present as dust, aerosol, or in gaseous elemental form (for example, mercury).

It is worth noting that lead, cadmium, copper and zinc aerosols include mainly submicron particles, the diameter of which is approximately 0.5 - 1 microns.

But nickel and cobalt particles in the form of an aerosol are coarse particles with a diameter exceeding 1 micron. Their formation mainly occurs during the combustion of diesel fuel.

In the aquatic environment, heavy metals can be present in three main forms: suspended particles, colloidal particles, and dissolved compounds.

The latter are free ions and soluble complex compounds with organic (humic and fulvic acids) and inorganic (halogens, sulfates, phosphates, carbonates) ligands.

The form of an element in water is determined by hydrolysis, which greatly influences the presence of these elements in the aquatic environment. A huge amount of heavy metals are transported through surface water in suspension.

heavy metals in soils are presented in water-soluble, ion-exchange and weakly adsorbed forms. The former are mainly chlorides, nitrates, sulfates, as well as organic complex compounds. It should be said that the connection of heavy metal ions with soil minerals, as part of the crystal lattice, is often noted.

The table presents the biogeochemical properties of heavy metals, which were assessed according to three main criteria: high (H), moderate (U), low (L).

It is worth noting that the biogeochemical properties of heavy metals include toxicity, carcinogenicity, solubility and many others, which are expressed differently in them. However, there are two main properties, on the basis of which the degree of danger of a particular heavy metal for a living organism is determined, depending on the concentration. These properties include: biochemical activity and organic form of distribution.

Determination of heavy metals

Today, there are two main groups of analytical methods that allow the determination of heavy metals (for example, in water or soil), namely:

• electrochemical methods;
• spectrometric methods.

It is worth noting that the second group is gradually losing ground and giving way to electrochemical methods.

Among the spectrometric methods, the most common one should be highlighted - atomic absorption spectrometry with different atomization of samples. In the case when it is necessary to determine several elements simultaneously, the main method of determination is atomic emission spectrometry with inductively coupled plasma, as well as mass spectrometry with inductively coupled plasma.

In order to determine heavy metals by electrochemical methods, the sample is transferred to an aqueous solution. Electrochemical methods include: polarographic (voltammetric), potentiometric, coulometric, conductometric and many others.

It is worth noting that there are situations when it is impossible to determine heavy metals using only one method, then several methods are used at once with further titration.

These methods are based on the analysis of current-voltage characteristics, the potentials of ion-selective electrodes, the integral charge, which serves to ensure that the desired metal precipitates on the electrode of the electrochemical cell, the electrical conductivity of the solution, etc. These methods make it possible to determine heavy metals up to 10-9 mol/l.

The group of spectral analyzes includes many different methods used to determine heavy metals. First of all, it includes in its list atomic emission analysis, atomic absorption analysis, spectrophotometry, mass spectrometry, inductively coupled plasma spectrometry, and X-ray spectral analysis.

In some cases, when the concentration of heavy metals is in a fairly small concentration, they are often determined by several spectrometric methods.

Sometimes, to determine heavy metals, it is necessary to resort to complex methods that combine both spectral and electrochemical methods. One such method is spectropolarimetric analysis.

The heaviest metal

It is impossible to identify and name one single heaviest metal, since the criteria for determining the “heaviness” of a metal can be completely different. This was discussed at the beginning of this article.

Thus, one of the heaviest metals is lead, which is not inferior to zinc, tin, iron, and copper, but it cannot bear the title of the heaviest metal. For example, lead is significantly inferior to liquid metal - mercury. So, if you place a piece of lead in mercury, it will not sink, but will confidently stay on its surface.

A 1 liter bottle of mercury will weigh 14 kg. But, despite this, mercury is not the heaviest metal, since gold and platinum are one and a half times heavier than mercury.

Rare metals ahead of gold and platinum are iridium and osmium, which are twice as heavy as iron. So, the heaviest metals, according to their specific gravity:

• zinc – 7.1;
• tin – 7.3;
• iron – 7.8;
• copper – 8.9;
• lead – 11.3;
• mercury – 13.6;
• gold – 19.3;
• platinum – 21.5;
• iridium – 22.4;
• osmium – 22.5

If we take density as the main characteristic of heavy metals, the list will be different and will include the following elements:

• tantalum – 16.67 g/cm3;
• uranium – 19.05 g/cm3;
• tungsten – 19.29 g/cm3;
• gold – 19.29 g/cm3;
• plutonium – 19.80 g/cm3;
• neptunium – 20.47 g/cm3;
• rhenium – 21.01 g/cm3;
• platinum – 21.40 g/cm3;
• osmium – 22.61 g/cm3;
• iridium – 22.65 g/cm3;

However, there is a list of metals that are generally considered heavy. Main heavy metals:

• lead;
• mercury;
• copper;
• cadmium;
• cobalt.

The peculiarities of heavy metals are that they are all highly toxic and in some cases pose a threat to the health and life of living organisms. In addition, they have the ability to bioaccumulate and biomagnify.

Application of heavy metals

In ancient times, the first metals that appeared in human life significantly facilitated his existence on Earth. After all, metal is a more durable material than stone or wood. More productive tools, more destructive weapons, and also more reliable protection were made from metal. In addition, people also learned to make jewelry, dishes, various ritual objects, and everyday items from metal.

Today, humanity knows about 70 metals, some of which, according to various definitions and selection criteria, are heavy.

Thanks to their unique properties and characteristics, heavy metals have found their application in many areas of human activity, in particular in mechanical engineering, shipbuilding, aircraft manufacturing, medicine, production of equipment and electronics, construction, in the production of dishes, jewelry, and everyday items.

For example, lead is used to coat various equipment to protect it from corrosion. It is also used as a sheath for cables that are laid underground, in water or any other wet environment. Lead batteries are still used to ignite internal combustion engines, despite the fact that nickel batteries have long existed in nature, however, the cost of the latter is much higher.

Mercury has also found its wide application in electrical engineering, electronics, instrument making, metallurgy, chemistry (manufacture of thermometers, barometers, relays, fluorescent lamps, quartz mercury lamps), etc.

Copper, due to its low resistivity and high thermal conductivity, is quite widely used in electrical engineering - it is the main material from which power and other cables, wires, and other conductors are made. Various heat exchangers are made from copper - cooling, air conditioning, heating radiators, computer coolers, heat pipes and much more.

These elements are extracted from heavy metal ores - the ore is initially extracted, after which it is enriched and then the metal itself is obtained using chemical or electrolytic reduction.

Source: http://mining-prom.ru/cvetmet/metallurgy/tyazhelye-metally/

Which heavy metals are considered the most dangerous?

Of all 104 chemical elements known to mankind today, 82 are metals. They occupy a prominent place in the lives of people in the industrial, biological and environmental spheres. Modern science divides metals into heavy, light and noble. In this article we will look at the list of heavy metals and their features.

What are heavy metals?

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Question for experts: what are heavy metals?

Best regards, User deleted

Best answers

This is when they are very difficult to wear around the neck and other places

These are metals from the bottom of the periodic table, their peculiarity is that once they enter the body they are practically not excreted and are very harmful

Everything is very simple - these are metals with a large atomic mass, well over 200. See the periodic table

You know how to communicate on the Internet, but you can’t read chemistry for the 7th grade. Amazing!!!

Despite the apparent clarity of the concept of “heavy metals,” its meaning should be defined more clearly due to ambiguous assessments found in the literature. The term "heavy metals" is associated with high relative atomic mass. This characteristic is usually identified with the idea of ​​high toxicity.

One of the characteristics that allows us to classify metals as heavy is their density. In modern non-ferrous metallurgy, a distinction is made between heavy non-ferrous metals - density 7.14-21.4 g/cm3 (zinc, tin, copper, lead, chromium, etc.) and light non-ferrous metals - density 0.53-3.5 g/cm3 (lithium, beryllium, etc.).

According to one classification, the group of heavy metals includes more than 40 elements with a high relative atomic mass and a relative density greater than 6. According to another classification, this group includes non-ferrous metals with a density greater than that of iron (lead, copper, zinc, nickel, cadmium , cobalt, tin, antimony, bismuth, mercury).

According to the information presented in the “Handbook of Elementary Chemistry,” ed. A. T. Pilipenko (1977), heavy metals include elements whose density is more than 5 g/cm3. Based on this indicator, 43 of the 84 metals in the Periodic Table of Elements should be considered heavy.

Among these 43 metals, 10 have, along with metallic properties, characteristics of non-metals (representatives of the main subgroups VI, V, IV, III of groups of the Periodic Table, which are p-elements), therefore the term “heavy elements” would be more strict, but in this publication we will use the term “heavy metals” generally accepted in the literature.

Thus, heavy metals include more than 40 chemical elements with a relative density of more than 6. The number of dangerous pollutants, taking into account the toxicity, persistence and ability to accumulate in the external environment, as well as the scale of distribution of these metals, is much smaller.

First of all, those metals of interest are those that are most widely and in significant volumes used in industrial activities and, as a result of accumulation in the external environment, pose a serious danger in terms of their biological activity and toxic properties. These include lead, mercury, cadmium, zinc, bismuth, cobalt, nickel, copper, tin, antimony, vanadium, manganese, chromium, molybdenum and arsenic.

You realize this when it falls on your foot (and you think “how heavy it really is”)

answer

This video will help you figure it out

Answers from experts

Heavy metals are elements of the periodic table with a relative molecular weight greater than 40 (lead, mercury, arsenic, cadmium, copper, nickel, zinc, chromium,)

cast iron is a heavy metal, and aluminum is light

heavy metal... child metal listen to Ozzy Osbourne, you'll understand

Having a metallic luster, high electrical and thermal conductivity, and ductility.

this is in chemistry, in natural sciences

for me - having a metal crystal lattice

your cap

Metals (from Latin metallum - mine, mine) are a group of elements, in the form of simple substances, with characteristic metallic properties, such as high thermal and electrical conductivity, positive temperature coefficient of resistance, high ductility and metallic luster.

Of the 118 chemical elements discovered so far (not all of them are officially recognized), metals include:

6 elements in the alkali metal group, Li, Na, K, Rb, Cs, Fr

4 in the group of alkaline earth metals, Ca, Sr, Ba, Ra

38 in the group of transition metals,

— Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn;
— Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd; — La, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg;

7 in the group of light metals, Al, Ga, In, Sn, Tl, Pb, Bi

7 in the group of semimetals, B, Si, Ge, As, Sb, Te, Po

14 in the lanthanide + lanthanum group, (La), Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu

14 in the group actinides (physical properties have not been studied for all elements) + actinium, (Ac), Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr

outside of certain groups beryllium and magnesium.

Thus, 94 of all discovered elements may be metals.

In astrophysics, the term "metal" can have a different meaning and refer to all chemical elements heavier than helium.
Some metals:

1) Alkaline: Lithium, Sodium, Potassium, Rubidium, Cesium, Francium 2) Alkaline earth: Calcium Strontium Barium Radium 3) Transitional: Uranium Titanium Iron Platinum Copper Zinc Gold Silver Palladium Mercury Nickel Cobalt Tungsten 4) Light: Aluminum Gallium Lead Tin 5) Others: Beryllium

Magnesium

Source: https://dom-voprosov.ru/prochee/chto-otnositsya-k-tyazhyolym-metallam