Cadmium: facts and facts. Cadmium: effects on the human body. Heavy metal poisoning Give the numerical values ​​of the main parameters of cadmium

Cadmium- an element of a secondary subgroup of the second group, the fifth period of the periodic system of chemical elements of D. I. Mendeleev, with atomic number 48. It is designated by the symbol Cd (Latin Cadmium). A soft malleable ductile transition metal of a silvery-white color.

The district doctor Rolov was distinguished by a tough disposition. So, in 1817, he ordered to withdraw from sale all preparations with zinc oxide produced at Hermann's Shenbeck factory. By the appearance of the preparations, he suspected that there was arsenic in zinc oxide! (Zinc oxide is still used for skin diseases; ointments, powders, and emulsions are made from it.)
To prove his case, the strict inspector dissolved the suspected oxide in acid and passed hydrogen sulfide through this solution: a yellow precipitate fell out. Arsenic sulfides are just yellow!
The owner of the factory began to challenge Rolov's decision. He was a chemist himself and, having personally analyzed product samples, did not find any arsenic in them. He reported the results of the analysis to Rolov, and at the same time to the authorities of the state of Hanover. The authorities naturally demanded samples in order to send them for analysis to one of the reputable chemists. It was decided that the judge in the dispute between Rolow and Hermann should be Professor Friedrich Stromeyer, who since 1802 held the Department of Chemistry at the University of Göttingen and the post of inspector general of all Hanoverian pharmacies.
Stromeyer was sent not only oxide, but also other zinc preparations from Hermann's factory, including ZnCO3, from which this oxide was obtained. Having calcined zinc carbonate, Stromeyer received oxide, but not white, as it should have been, but yellowish. The owner of the factory explained the color by an admixture of iron, but Stromeyer was not satisfied with this explanation. Having bought more zinc preparations, he made a complete analysis of them and, without much difficulty, isolated the element that caused the yellowing. Analysis said it was not arsenic (as Rolov claimed), but not iron (as Herman argued).

It was a new, previously unknown metal, chemically very similar to zinc. Only its hydroxide, unlike Zn (OH) 2, was not amphoteric, but had pronounced basic properties.

Element 48 of the periodic table In its free form, the new element was a white metal, soft and not very strong, covered on top with a brownish oxide film. Stromeyer called this metal cadmium, clearly hinting at its "zinc" origin: the Greek word καδμεια has long been used to denote zinc ores and zinc oxide.

In 1818, Stromeyer published detailed information about the new chemical element, and almost immediately they began to encroach on its priority. The first to speak was the same Rolov, who had previously believed that the preparations from Herman's factory contained arsenic. Soon after Stromeyer, another German chemist, Kersten, found a new element in the Silesian zinc ore and named it mellin (from the Latin mellinus - "yellow as quince") because of the color of the sediment formed by the action of hydrogen sulfide. But this was cadmium already discovered by Stromeyer. Later, two more names were proposed for this element: claprothium - in honor of the famous chemist Martin Klaproth and Junonium - after the asteroid Juno discovered in 1804. But the name given to the element by its discoverer was still firmly established. True, in the Russian chemical literature of the first half of the 19th century. cadmium was often called cadm.

What is Cadmium? It is a heavy metal that is obtained from the smelting of other metals such as zinc, copper or lead. It is widely used to make nickel-cadmium batteries. In addition, cigarette smoke also contains such an element. As a result of continuous exposure to cadmium, very serious diseases of the lungs and kidneys occur. Let's consider the features of this metal in more detail.

Scope of application of cadmium

Most of the industrial use of this metal is in protective coatings that protect metals from corrosion. Such a coating has a great advantage over zinc, nickel or tin, because it does not peel off during deformation.

What other uses for cadmium can there be? It is used to produce alloys that are remarkably machinable. Cadmium alloys with minor additions of copper, nickel and silver are used for the manufacture of bearings for automobile, aircraft and marine engines.

Where else is cadmium used?

Welders, metallurgists and workers associated with the textile, electronics and battery industries are the most at risk of cadmium poisoning. Nickel-cadmium batteries are used in mobile phones and other electronic devices. This metal is also used in the production of plastics, paints, metal coatings. Many soils that are regularly fertilized can also contain high levels of this toxic metal.

cadmium: properties

Cadmium as well as its compounds are characterized as, but it has not been proven that a small amount of the element in the environment causes cancer. Inhalation of metal particles in industrial production does contribute to the development of lung cancer, but when they eat contaminated food, they do not pose a risk of developing cancer.

How does cadmium enter the human body?

Everyone has known for a long time that cigarette smoke contains cadmium. This heavy metal enters the body of a smoker in an amount twice as much as that of a person who is not subject to such a bad habit. However, secondhand smoke can be harmful.

Leafy vegetables, grains and potatoes grown in soils high in cadmium can pose a threat. The liver and kidneys of marine life and animals are also famous for the increased content of this metal.

Many industrial enterprises, especially metallurgical ones, emit large amounts of cadmium into the atmosphere. People living near such enterprises are automatically included in the risk group.

Some agricultural areas actively use phosphate fertilizers, which contain trace amounts of cadmium. Products grown on this land pose a potential threat to humans.

The effect of cadmium on the human body

Thus, we have sorted out what cadmium is. The impact on the human body of this heavy metal can cause negative consequences. In any living organism, it is found in an insignificant amount, and its biological role is still not fully understood. Usually cadmium is associated with negative function.

Its toxic effect is based on blocking sulfur-containing amino acids, which leads to disruption of protein metabolism and damage to the cell nucleus. This heavy metal promotes the removal of calcium from the bones and damages the nervous system. It can accumulate in the kidneys and liver, and it is excreted from the body very slowly. This process can take decades. Usually, cadmium is excreted in urine and feces.

Inhalation of cadmium

This element is absorbed into the body of industrial workers by inhalation. To prevent this, use effective protective equipment. Disregard of this rule leads to sad consequences. If cadmium is inhaled, the effect of such a metal on the human body is manifested as follows: the body temperature rises, chills and muscle pain appear.

After a while, lung damage occurs, chest pain, shortness of breath, and coughing occur. In severe cases, this condition causes the death of the patient. Inhalation of air containing cadmium contributes to the development of kidney disease and osteoporosis. The likelihood of lung cancer increases several times.

Intake of cadmium with food

Why is cadmium in water and food dangerous? With the regular use of contaminated foods and water, this metal begins to accumulate in the body, which leads to negative consequences: kidney function is disrupted, bone tissue is weakened, liver and heart are affected, and in severe cases death occurs.

Eating foods contaminated with cadmium can cause stomach irritation, nausea, abdominal pain, diarrhea, and vomiting. In addition, flu-like symptoms appear, laryngeal edema develops and tingling in the hands occurs.

Causes of cadmium poisoning

Heavy metal poisoning most often occurs in children, diabetics, pregnant and lactating women, people who abuse smoking. In Japan, cadmium intoxication occurs as a result of eating contaminated rice. In this case, apathy develops, kidneys are affected, bones soften and deform.

Industrialized regions, where oil refineries and metallurgical enterprises are located, are famous for the fact that the soil there is contaminated with cadmium. If plant products are grown in such places, then there is a high probability that heavy metal poisoning will occur.

The element can accumulate in large quantities in tobacco. If the raw material is dried, then the metal content rises sharply. The intake of cadmium into the body occurs both with active and with the occurrence of lung cancer directly depends on the content of metal in the smoke.

Treatment for poisoning

Cadmium:

• damage to the central nervous system;
• sharp bone pain;
• protein in the urine;
• stones in the kidneys;
• dysfunction of the genitals.

If acute poisoning occurs, the victim should be kept warm, he needs to provide an influx of fresh air and rest. After washing the stomach, he needs to be given warm milk, to which a little baking soda is added. There are no antidotes for cadmium. Unithiol, steroids and diuretics are used to neutralize the metal. Complex treatment involves the use of cadmium antagonists (zinc, iron, selenium, vitamins). The doctor may prescribe a general tonic diet that is high in fiber and pectin.

Possible consequences

A metal such as cadmium has a very serious effect on the human body, and if poisoning with this element occurs, the consequences can be dangerous. It displaces calcium from the bones, contributing to the development of osteoporosis. In adults and children, the spine begins to bend and bone deformation occurs. In childhood, such poisoning leads to encephalopathy and neuropathy.

Output

Thus, we have sorted out what a heavy metal like cadmium is. The influence of this element on the human body is quite serious. Gradually accumulating in the body, it leads to the destruction of many organs. You can even get poisoned with cadmium if you eat a lot of contaminated foods. The consequences of poisoning are also quite dangerous.

Cadmium

CADMIUM-I am; m.[lat. cadmium from Greek. kadmeia - zinc ore]

1. A chemical element (Cd), a silvery-white soft, viscous metal contained in zinc ores (it is part of many low-melting alloys, used in the nuclear industry).

2. Artificial yellow paint in different shades.

◁ Cadmium, th, th. K-th alloys. K-th yellow(dye).

(lat. Cadmium), chemical element of group II of the periodic system. The name is from the Greek kadméia - zinc ore. A silvery metal with a bluish sheen, soft and fusible; density 8.65 g / cm 3, t pl 321.1ºC. They are mined during the processing of lead-zinc and copper ores. They are used for cadmium plating, in high-power accumulators, in nuclear power engineering (control rods of reactors), for the production of pigments. It is a part of low-melting and other alloys. Cadmium sulfides, selenides and tellurides are semiconducting materials. Many cadmium compounds are poisonous.

Cadmium (lat. Cadmium), Cd (read "cadmium"), a chemical element with atomic number 48, atomic mass 112.41.
Natural cadmium consists of eight stable isotopes: 106 Cd (1.22%), 108 Cd (0.88%), 110 Cd (12.39%), 111 Cd (12.75%), 112 Cd (24.07 %), 113 Cd (12.26%), 114 Cd (28.85%) and 116 Cd (12.75%). Located in the 5th period in group IIB of the periodic table of elements. Configuration of the two outer electronic layers 4 s 2 p 6 d 10 5s 2 ... Oxidation state +2 (valence II).
The radius of the atom is 0.154 nm, the radius of the Cd 2+ ion is 0.099 nm. The sequential ionization energies are 8.99, 16.90, 37.48 eV. Pauling electronegativity (cm. POLING Linus) 1,69.
Discovery history
Discovered by the German professor F. Stromeyer (cm. STROMEIER Friedrich) in 1817. Pharmacists of Magdeburg in the study of zinc oxide (cm. ZINC (chemical element)) ZnO was suspected of arsenic impurity (cm. ARSENIC)... F. Stromeyer isolated brown-brown oxide from ZnO, reduced it with hydrogen (cm. HYDROGEN) and received a silvery-white metal, which was named cadmium (from the Greek kadmeia - zinc ore).
Being in nature
Content in the earth's crust is 1.35 · 10 -5% by weight, in the water of seas and oceans 0.00011 mg / l. Several very rare minerals are known, for example, greenockite GdS, otavite CdCO 3, monteponite CdO. Cadmium accumulates in polymetallic ores: sphalerite (cm. SPHALERITE)(0.01-5%), galena (cm. GALENA)(0.02%), chalcopyrite (cm. HALCOPIRITE)(0.12%), pyrite (cm. PYRITE)(0.02%), fahlores (cm. BLUE ORE) and stannina (cm. STANNIN)(up to 0.2%).
Receiving
The main sources of cadmium are intermediate products of zinc production, dust from lead and copper smelters. The raw material is treated with concentrated sulfuric acid and CdSO 4 is obtained in solution. Cd is isolated from the solution using zinc dust:
CdSO 4 + Zn = ZnSO 4 + Cd
The resulting metal is purified by remelting under a layer of alkali to remove zinc and lead impurities. High-purity cadmium is obtained by electrochemical refining with intermediate purification of the electrolyte or by zone melting (cm. ZONE MELT).
Physical and chemical properties
Cadmium is a silvery white soft metal with a hexagonal lattice ( a = 0,2979, with= 0.5618 nm). Melting point 321.1 ° C, boiling point 766.5 ° C, density 8.65 kg / dm 3. If the cadmium stick is bent, then you can hear a faint crackling - it is the metal microcrystals rubbing against each other. Standard electrode potential of cadmium -0.403 V, in the range of standard potentials (cm. STANDARD CAPACITY) it is located before hydrogen (cm. HYDROGEN).
In a dry atmosphere, cadmium is stable, in a humid atmosphere it gradually becomes covered with a film of CdO oxide. Above the melting point, cadmium burns in air with the formation of brown CdO oxide:
2Cd + O 2 = 2CdO
Cadmium vapors react with water vapor to form hydrogen:
Cd + H 2 O = CdO + H 2
Compared to its neighbor in group IIB - Zn, cadmium reacts more slowly with acids:
Сd + 2HCl = CdCl 2 + H 2
The reaction proceeds most easily with nitric acid:
3Cd + 8HNO 3 = 3Cd (NO 3) 2 + 2NO - + 4H 2 O
Cadmium does not react with alkalis.
In reactions, it can act as a mild reducing agent, for example, in concentrated solutions, it is able to reduce ammonium nitrate to NH 4 NO 2 nitrite:
NH 4 NO 3 + Cd = NH 4 NO 2 + CdO
Cadmium is oxidized by solutions of Cu (II) or Fe (III) salts:
Cd + CuCl 2 = Cu + CdCl 2;
2FeCl 3 + Cd = 2FeCl 2 + CdCl 2
Above the melting point, cadmium reacts with halogens (cm. HALOGENS) with the formation of halides:
Cd + Cl 2 = CdCl 2
With gray (cm. SULFUR) and other chalcogenes forms chalcogenides:
Cd + S = CdS
Cadmium does not react with hydrogen, nitrogen, carbon, silicon and boron. Cd 3 N 2 nitride and CdH 2 hydride are obtained indirectly.
In aqueous solutions, cadmium ions Cd 2+ form aqua complexes 2+ and 2+.
Cadmium hydroxide Cd (OH) 2 is obtained by adding alkali to the cadmium salt solution:
СdSO 4 + 2NaOH = Na 2 SO 4 + Cd (OH) 2 Ї
Cadmium hydroxide practically does not dissolve in alkalis, although during prolonged boiling in very concentrated alkali solutions the formation of hydroxide complexes 2– is recorded. Thus, amphoteric (cm. AMPHOTHERIC) the properties of cadmium oxide CdO and hydroxide Cd (OH) 2 are much weaker than those of the corresponding zinc compounds.
Cadmium hydroxide Cd (OH) 2, due to complexation, easily dissolves in aqueous solutions of ammonia NH 3:
Cd (OH) 2 + 6NH 3 = (OH) 2
Application
40% of the cadmium produced is used for the application of anti-corrosion coatings to metals. 20% of cadmium goes to the manufacture of cadmium electrodes used in batteries, normal Weston cells. About 20% of cadmium is used for the production of inorganic dyes, special solders, semiconductor materials and phosphors. 10% cadmium is a component of jewelry and low-melting alloys, plastics.
Physiological action
Vapors of cadmium and its compounds are toxic, and cadmium can accumulate in the body. In drinking water, the maximum permissible concentration for cadmium is 10 mg / m 3. Symptoms of acute poisoning with cadmium salts are vomiting and convulsions. Soluble cadmium compounds, after being absorbed into the blood, affect the central nervous system, liver and kidneys, and disrupt phosphorus-calcium metabolism. Chronic poisoning leads to anemia and bone destruction.

encyclopedic Dictionary. 2009 .

See what "cadmium" is in other dictionaries:

- (lat.cadmium). A viscous metal, similar in color to tin. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. CADMIUS lat. cadmium, from kadmeia gea, cadmium earth. A metal that looks like tin. Explanation of 25,000 foreign ... ... Dictionary of foreign words of the Russian language

CADMIUM- CADMIUM, Cadmium, chem. element, char. Cd, atomic weight 112.41, serial number 48. It is contained in small quantities in most zinc ores and is obtained as a by-product when zinc is mined; can also be obtained ... ... Great medical encyclopedia

CADMIUM- see CADMIUM (Cd). Contained in the branch waters of many industrial enterprises, especially lead-zinc and metal-working plants using electroplating. It is present in phosphate fertilizers. Sulfuric acid dissolves in water, ... ... Fish Diseases: A Handbook

Cadmium- (Cd) silvery white metal. It is used in nuclear power engineering and electroplating, is a part of alloys, is used for the preparation of printing plates, solders, welding electrodes, in the production of semiconductors; is a component ... ... Russian encyclopedia of labor protection

- (Cadmium), Cd, chemical element of group II of the periodic system, atomic number 48, atomic mass 112.41; metal, m.p. 321.1shC. Cadmium is used for applying anti-corrosion coatings on metals, making electrodes, obtaining pigments, ... ... Modern encyclopedia

- (symbol Cd), a silvery white metal from the second group of the periodic table. First isolated in 1817. Contained in greenockite (in the form of sulfide), but it is mainly obtained as a by-product in the extraction of zinc and lead. Easy to forge ... Scientific and technical encyclopedic dictionary

Cd (from the Greek kadmeia zinc ore * a. Cadmium; n. Kadmium; f. Cadmium; and. Cadmio), chem. element of group II periodic. Mendeleev system, at.n. 48, at. m. 112.41. In nature, there are 8 stable isotopes 106Cd (1.225%) 108Cd (0.875%), ... ... Geological encyclopedia

Husband. metal (one of the chemical principles or non-degradable elements) found in zinc ore. Cadmium, related to cadmium. Admisty containing cadmium. Dahl's Explanatory Dictionary. IN AND. Dahl. 1863 1866 ... Dahl's Explanatory Dictionary

Cadmium- (Cadmium), Cd, chemical element of group II of the periodic system, atomic number 48, atomic mass 112.41; metal, m.p. 321.1 ° C. Cadmium is used for applying anti-corrosion coatings on metals, making electrodes, obtaining pigments, ... ... Illustrated Encyclopedic Dictionary

CADMIUM- chem. element, symbol Cd (Latin Cadmium), at. n. 48, at. m. 112.41; silvery white shiny soft metal, density 8650 kg / m3, melting point = 320.9 ° С. Cadmium is a rare and trace element, poisonous, usually found in ores together with zinc, for which ... ... Big Polytechnic Encyclopedia

- (lat. Cadmium) Cd, chemical element of group II of the periodic system, atomic number 48, atomic mass 112.41. The name is from the Greek kadmeia zinc ore. A silvery metal with a bluish sheen, soft and fusible; density 8.65 g / cm & sup3, ... ... Big Encyclopedic Dictionary

Cadmium(Cadmium), Cd, chemical element of group II of Mendeleev's periodic system; atomic number 48, atomic weight 112.40; white, shiny, heavy, soft, stringy metal. The element consists of a mixture of 8 stable isotopes with mass numbers: 106 (1.215%), 108 (0.875%), 110 (12.39%), 111 (12.75%), 112 (24.07%), 113 (12 , 26%), 114 (28.86%), 116 (7.58%).

Historical reference. In 1817, the German chemist F. Stromeyer, during an audit of one of the pharmacies, found that the zinc carbonate there contained an admixture of an unknown metal, which was precipitated in the form of yellow sulfide by hydrogen sulfide from an acidic solution. Stromeyer called the metal he discovered cadmium (from the Greek kadmeia - impure zinc oxide, also zinc ore). Independently of him, German scientists K. Hermann, K. Carsten and W. Meissner discovered Cadmium in Silesian zinc ores in 1818.

Distribution of cadmium in nature. Cadmium is a rare and trace element with a lithosphere clarke of 1.3 · 10 -5% by weight. Cadmium is characterized by migration in hot groundwater together with zinc and other chalcophilic elements and concentration in hydrothermal deposits. Mineral sphelerite ZnS in some places contains up to 0.5-1% Cd, up to a maximum of 5%. Greenockite CdS is less common. Cadmium is concentrated in marine sedimentary rocks - shales (Mansfeld, Germany), in sandstones, in which it is also associated with zinc and other chalcophilic elements. Three very rare independent minerals of cadmium are known in the biosphere - carbonate CdCO 3 (poses), oxide CdO (monteponite) and selenide CdSe.

Physical properties of Cadmium. The crystal lattice of cadmium is hexagonal, a = 2.97311 Å, c = 5.60694 Å (at 25 ° C); atomic radius 1.56 Å, ionic radius Cd 2+ 1.03 Å. Density 8.65 g / cm 3 (20 ° C), melting point 320.9 ° C, boiling point 767 ° C, coefficient of thermal expansion 29.8 · 10 -6 (at 25 ° C); thermal conductivity (at 0 ° C) 97.55 W / (m K) or 0.233 cal / (cm sec ° C); specific heat (at 25 ° C) 225.02 J / (kg K) or 0.055 cal / (g ° C); electrical resistivity (at 20 ° C) 7.4 · 10 -8 ohm · m (7.4 · 10 -6 ohm · cm); temperature coefficient of electrical resistance 4.3 · 10 -3 (0-100 ° C). Tensile strength 64 MN / m 2 (6.4 kgf / mm 2), elongation 20%, Brinell hardness 160 MN / m 2 (16 kgf / mm 2).

Chemical properties of Cadmium. In accordance with the external electronic configuration of the 4d 10 5s 2 atom, the valence of Cadmium in the compounds is 2. In air, Cadmium tarnishes, becoming covered with a thin film of CdO oxide, which protects the metal from further oxidation. On strong heating in air, cadmium burns into oxide CdO - a crystalline powder from light brown to dark brown color, density 8.15 g / cm 3; at 700 ° C, CdO sublimes without melting. Cadmium binds directly to halogens; these compounds are colorless; CdCl 2, CdBr 2 and CdI 2 are very easily soluble in water (about 1 part of anhydrous salt in 1 part of water at 20 ° C), CdF 2 is more difficult to dissolve (1 part in 25 parts of water). With sulfur, Cadmium forms sulfide CdS from lemon-yellow to orange-red color, insoluble in water and dilute acids. Cadmium readily dissolves in nitric acid with the release of nitrogen oxides and the formation of nitrate, which gives the hydrate Cd (NOa) 2 5H 2 O and sulfate 3CdSO 4 · 8H 2 O. Cadmium salt solutions have an acidic reaction due to hydrolysis; caustic alkalis precipitate from them the white hydroxide Cd (OH) 2, insoluble in an excess of the reagent; however, under the action of concentrated alkali solutions on Cd (OH) 2, hydroxocadmiates, for example, Na 2, were obtained. The Cd 2+ cation readily forms complex ions with ammonia 2+ and with cyanogen 2- and 4-. Numerous basic, double and complex cadmium salts are known. Cadmium compounds are poisonous; inhalation of its oxide vapor is especially dangerous.

Obtaining Cadmium. Cadmium is obtained from by-products of processing zinc, lead-zinc and copper-zinc ores. These products (containing 0.2-7% cadmium) are treated with dilute sulfuric acid, which dissolves cadmium and zinc oxides. Cadmium is precipitated from the solution with zinc dust; the spongy residue (a mixture of cadmium and zinc) is dissolved in dilute sulfuric acid and cadmium is isolated by electrolysis of this solution. Electrolytic cadmium is remelted under a layer of caustic soda and cast into sticks; metal purity - not less than 99.98%.

Application of Cadmium. Metallic cadmium is used in nuclear reactors, for anti-corrosion and decorative coatings, in batteries. Cadmium is the basis of some bearing alloys and is part of low-melting alloys (for example, Wood's alloy). Low-melting alloys are used for bonding glass to metal, in automatic fire extinguishers, for thin and complex castings in plaster molds, and others. Cadmium sulfide (cadmium yellow) - paint for painting. Cadmium sulfate and amalgam are used in the normal Weston cell.

Cadmium in the body. The content of cadmium in plants is 10 -4% (on dry matter); in some animals (sponges, coelenterates, worms, echinoderms and tunicates) - 4-10 -5 - 3-10 -3% of dry matter. Found in all vertebrates. The liver is richest in cadmium. Cadmium affects carbohydrate metabolism, the synthesis of hippuric acid in the liver, and the activity of certain enzymes.

DEFINITION

Cadmium- the forty-eighth element of the Periodic Table. Designation - Cd from the Latin "cadmium". Located in the fifth period, IIB group. Refers to metals. The core has a charge of 48.

In terms of its properties, cadmium is similar to zinc and is usually found as an impurity in zinc ores. In terms of prevalence in nature, it is significantly inferior to zinc: the cadmium content in the earth's crust is only about 10 -5% (wt.).

Cadmium is a silvery white (Fig. 1) soft, malleable, ductile metal. In the series of voltages, it stands farther than zinc, but ahead of hydrogen and displaces the last of the acids. Since Cd (OH) 2 is a weak electrolyte, cadmium salts are hydrolyzed and their solutions are acidic.

Rice. 1. Cadmium. Appearance.

Atomic and molecular weight of cadmium

Relative molecular weight of the substance(M r) is a number showing how many times the mass of a given molecule is greater than 1/12 of the mass of a carbon atom, and relative atomic mass of an element(A r) - how many times the average mass of atoms of a chemical element is more than 1/12 of the mass of a carbon atom.

Since in the free state cadmium exists in the form of monatomic Cd molecules, the values ​​of its atomic and molecular masses coincide. They are equal to 112.411.

Cadmium isotopes

It is known that in nature, cadmium can be found in the form of eight stable isotopes, two of which are radioactive (113 Cd, 116 Cd): 106 Cd, 108 Cd, 110 Cd, 111 Cd, 112 Cd and 114 Cd. Their mass numbers are 106, 108, 110, 111, 112, 113, 114 and 116, respectively. The nucleus of the cadmium isotope 106 Cd contains forty-eight protons and fifty-eight neutrons, and the rest of the isotopes differ from it only in the number of neutrons.

Cadmium ions

At the external energy level of the cadmium atom, there are two electrons, which are valence:

1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 5s 2.

As a result of chemical interaction, cadmium donates its valence electrons, i.e. is their donor, and turns into a positively charged ion:

Cd 0 -2e → Cd 2+.

Cadmium molecule and atom

In a free state, cadmium exists in the form of monoatomic Cd molecules. Here are some properties that characterize the atom and molecule of cadmium:

Cadmium alloys

Cadmium is included as a component in some alloys. For example, copper alloys containing about 1% cadmium (cadmium bronze) are used for the manufacture of telegraph, telephone, trolleybus wires, since these alloys have greater strength and wear resistance than copper. A number of low-melting alloys, such as those used in automatic fire extinguishers, contain cadmium.

Examples of problem solving

EXAMPLE 1

EXAMPLE 2