D. I. Mendeleev establishes the laws of dependence of the chemical properties of elements on their location. However, some elements may behave differently in physical and chemical processes than expected. Bismuth is a prime example. Let us consider this metal in more detail, focusing on the issue of the melting point of bismuth.

Looking at the periodic table, you can see that bismuth is symbolized as Bi, has the number 83, and has an atomic mass of 208.98 amu. In the earth's crust, it is found in small quantities (8.5 * 10 -7%) and is as rare as silver.

If we talk about the chemical properties of the element, then we should note its inertness and the difficulty of participating in reactions. The latter fact brings it closer to the group of noble metals. Externally, bismuth is a failure gray crystal with a pinkish tinge. The largest amount of this element is found in deposits in South America and the United States.

An element known from antiquity

Before considering the issue of the physical properties of bismuth and its melting point, it should be noted that the discovery of this element does not belong to anyone. Bismuth is one of the 10 metals that have been known to man since ancient times, in particular, according to some evidence, its compounds were used in ancient Egypt as cosmetics.

The origin of the word "bismuth" is not exactly known. The existing opinions of most experts are inclined to believe that it comes from the ancient Germanic words Bismuth or Wismut, which means "white mass".

Since the melting points of bismuth and lead are very close to each other (271.4 ° C and 327.5 ° C, respectively), and the densities of these metals are also close (9.78 g / cm 3 and 11.32 g / cm 3, respectively), then bismuth was constantly confused with lead, as well as with tin, the melting of which occurs at a temperature of 231.9 ° C. Only in the middle of the 18th century did European chemists demonstrate that bismuth is an independent metal.

Curious physical properties

Bismuth is an atypical metal. In addition to its chemical inertness and resistance to oxidation by oxygen, it is diamagnetic, a poor conductor of heat and electricity.

Even more curious is its transition from solid to liquid. As noted, the melting point of bismuth is lower than that of lead and is only 271.4 °C. During melting, the volume of the metal decreases, that is, solid pieces of metal do not sink in its melt, but float on the surface. In this property, it is similar to such semiconductors as gallium and silicon, as well as to water.

No less surprising is the resistance of bismuth to radioactive decay. It has been proved that any element of the D. I. Mendeleev table, which is to the right of niobium (that is, has a serial number greater than 41), is potentially unstable. Bismuth is located at number 83 and is the most stable heavy element, its half-life is estimated at 2 * 10 19 years. Due to its high density and high stability, it could replace lead shielding in nuclear power, but the rarity of bismuth in nature does not allow this.

Use of the element in human activity

Because bismuth is stable, chemically inert, and non-toxic, it is used in the manufacture of certain medicines and cosmetics.

The similarity of the element's physical properties to those of lead and tin allows it to be used as a substitute for them, since the latter two metals are toxic. For example, Denmark, the Netherlands, the United States and many other countries have banned the use of lead as a filler in hunting shots, because birds, confusing it with small pebbles, swallow lead and experience subsequent poisoning. Also, technologies for the production of bismuth sinkers for fishing are being developed in place of lead ones.

Since the melting points of tin and bismuth are close (the difference is only 40 °C), bismuth alloys with a low melting point are often used as a replacement for toxic lead-tin solders, especially in the manufacture of food packaging.

Problem with a new temperature scale

In the course of physics, you can meet the task of determining the melting point of bismuth on the Genius scale. Let's say right away that this is just a task, and there is no Genius scale. In physics, only three temperature scales are currently accepted: Celsius, Fahrenheit and Kelvin (in

So, the conditions of the problem are as follows: "The new temperature scale, which is expressed in degrees Genius (° G), is related to the Celsius scale as follows: 0 ° G \u003d 127 ° C and 80 ° G \u003d 255 ° С, you need to determine the melting point of bismuth in degrees new scale.

The complexity of the problem lies in the fact that the interval of 1 °G does not correspond to the interval of 1 °C. And what value does it correspond to in Celsius? Using the condition of the problem, we get: (255-127) / 80 = 1.6 ° C. This means that a 1°G increase in temperature will be equivalent to a 1.6°C increase. To solve the problem, remember that bismuth melts at a temperature of 271.4 ° C, which is 16.4 ° C or 10.25 ° G (16.4 / 1.6) more than the temperature of 255 ° C. Since a temperature of 255 °C corresponds to 80 °G, we find that on the Genius scale, bismuth will melt at a temperature of 90.25 °G (80 + 10.25).

From this article you will learn about where this metal is used and what interesting features it has. In particular, whether it is radioactive, how ornithologists used it, and what diseases are treated with bismuth-containing drugs.

Until recently, the only natural isotope of bismuth was considered stable, but in 2003 its radioactivity was proven. True, its half-life is several tens of times greater than the age of our Universe. So in terms of radioactivity, natural bismuth is completely safe for humans.

Due to the insolubility of compounds, bismuth is considered an environmentally friendly substance. Moreover, during the accident of an oil platform in the Gulf of Mexico, ornithologists fed seabirds with bismuth preparations to remove the oil that had entered their bodies.

Applications of bismuth

Metallurgy is the main consumer of bismuth. Steel and aluminum, containing only a few hundredths of a percent of Bi, are much easier to machine. Bismuth alloys with cadmium, lead, zinc and other metals make it possible to obtain substances with a melting point below 100 °C. Such alloys are smelted for the manufacture of:

- fuses, fuse valves;
- lead-free and low-melting solders;
- babbits for bearings;
- parts to replace environmentally harmful lead, for example, weights for fishing rods, valves for plumbing systems, shot for hunting cartridges;
- caps for armor-piercing shells;
— lubricants and sealing gaskets for vacuum operation;
— thermometric liquids for thermometers;
— coolants for nuclear reactors;
- material for fixing fractures in traumatology, for prosthetics in dentistry;
— materials for modeling in foundry production.

Highly pure bismuth is used to manufacture instruments for measuring magnetic fields, since its resistance varies almost linearly with the magnitude of the magnetic field.

It is impossible not to mention that fine jewelry is made from beautiful crystals of pure bismuth.

Bismuth alloys with manganese, chromium, indium or europium are used to produce high quality, powerful and durable permanent magnets. Bismuth compounds are used to produce magnetoelectric, high-temperature ferroelectric, thermoelectric, superconducting materials.
- Bi oxide with small additions of other metals is used for the manufacture of electrochemical fuel cells capable of operating at 500-700 °K.
— Compounds with gallium, iodine, germanium are in demand as detectors of ionizing radiation in devices for computed tomography, nuclear physics, and geology.
— Alloys and compounds are widely used for the manufacture of energy-intensive, stable and reliable batteries. For example, in batteries for space and military vehicles.
— Bismuth oxide and nitrate — catalysts in polymer production technology based on acrylic; bismuth in the form of chips - a catalyst for the manufacture of oxidizers for rocket fuel.
- Used to obtain polonium-210; in oil refining; for the production of pigments, low-temperature enamels for ceramics; nail polish.
- In medicine, bismuth compounds are part of drugs used to treat the gastrointestinal tract, oncological diseases; antiseptics, wound healing agents; contrast agent for fluoroscopy. Bismuth-containing drugs are one of the few drugs that are effective against the bacterium that causes stomach ulcers.

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BISMUTH, Bi (lat. bismuthum * a. bismuth; n. Wismut; f. bismuth; and. bismuto), is a chemical element of group V of the Mendeleev periodic system, atomic number 83, atomic mass 208.980.

Obtaining and using bismuth

Depending on the composition of impurities in crude bismuth extracted from concentrates, pure bismuth is obtained by various methods: oxidative refining under alkaline fluxes, seigerization, fusion with sulfur, etc. Commercial bismuth contains almost 100% of the base metal. Bismuth of high purity is obtained by zone recrystallization in an inert gas atmosphere.

Bismuth is used in metallurgy (obtaining fusible alloys with lead, tin, in the manufacture of molds for precision casting, dies, marking, mounting and control devices; to improve the machinability of alloys, cast iron and steel in the production of aircraft and auto engines). A significant amount of bismuth is consumed by the pharmaceutical industry (bismuth and its preparations are a disinfectant and drying agent). In the chemical industry, bismuth is a catalyst in the production of synthetic fibers. Bismuth is also used in the nuclear power industry (bismuth is a liquid coolant and coolant), electronics (bismuth-based semiconductors), glass (bismuth compounds increase the refractive index) and ceramic (fusible enamels) industries.

Bismuth is a heavy metal along with lead, antimony, and mercury. But due to the peculiarities of its chemical properties, it does not have a pronounced toxic effect compared to the above metals. Bismuth compounds were already used in medieval medicine for the treatment of syphilis, stomatitis and other diseases.

In modern medicine, there are a huge number of medicines based on bismuth compounds. The antiulcer properties of its compounds are used in the treatment of gastritis and stomach ulcers, diarrhea. Ointments based on bismuth compounds are used to treat dermatitis, erosions, ulcers, inflammatory diseases of the skin and mucous membranes. The widespread use of bismuth compounds is based on the antiulcer, anti-inflammatory, disinfectant, astringent, wound healing properties of this metal.

However, an overdose of bismuth is dangerous to human health and life.

Causes of bismuth poisoning

Excess intake of heavy metal occurs with uncontrolled and prolonged use of bismuth-containing medications. At the same time, a “bismuth border” is noted, which is an inflammatory process along the edges of the gum due to the deposition of bismuth salts. The color of the mucous membrane changes, it turns black. Intensive use of bismuth compounds for medical purposes in patients with kidney pathology leads to bismuth encephalopathy.

In production, bismuth is widely used in electrical engineering, the nuclear industry, and the chemical, metallurgical and pharmacological industries cannot do without it. Bismuth is used for the production of cosmetics, paints, pigments. In production, cases of poisoning with metal compounds are extremely rare and are the result of non-compliance with safety requirements at work.

Mechanism and symptoms of bismuth poisoning

When a large amount of metal enters the body, it is captured by leukocytes and spreads to all tissues and organs. The metal is deposited in the internal organs: liver, kidneys, spleen, nervous tissue. Bismuth is excreted from the body through the gastrointestinal tract. In this case, the stools are painted in a dark color due to bismuth sulfide.

The most common chronic poisoning with bismuth compounds, characterized by the following pathological manifestations:

• Common signs: deterioration of memory and attention, loss of appetite, impotence, decreased immunity.
• Manifestations of a neurological nature: insomnia, irritability, nervousness, changes in the sensitivity of body parts, muscle tremors, spasms, convulsions.
• From the side of the cardiovascular system: arrhythmia, changes in blood pressure.
• Changes in the digestive organs: nausea, vomiting, stomatitis, pain syndrome, diarrhea, toxic hepatitis.
• Skin manifestations: dermatitis, pigmentation of the oral mucosa, the formation of a "bismuth border".
• From the excretory system: renal failure, albuminuria.

Long-term use of bismuth-containing drugs in patients with diseased kidneys quickly leads to bismuth encephalopathy. Pathology is accompanied by headaches, fatigue, unmotivated aggression, decreased intelligence, asthenia, and the development of psychoses. Pathology may be accompanied by confusion, loss of balance, visual hallucinations.

In acute poisoning with bismuth preparations, acute renal failure, neurological disorders, oliguria, anuria, acute abdominal pain, vomiting, and diarrhea develop.

Diagnosis and treatment

Diagnosis of poisoning is based on anamnesis (taking bismuth medicines, working in production with bismuth-containing compounds), intestinal x-rays, a blood test for poison content, etc.

First aid is to immediately stop the flow of bismuth compounds into the body. In acute poisoning, the stomach is washed. The patient can be given 2 tablets of activated charcoal.

Treatment consists of chelation therapy. If necessary, gastric lavage is carried out, laxatives are prescribed. With the development of renal failure, hemodialysis is performed.

There are no specific antidotes for bismuth, but dimercaptol and unithiol have a good effect. Apply enterosorbents. With the development of stomatitis, a 1% solution of lapis is prescribed.

Prevention of poisoning with bismuth compounds is reduced primarily to a strict dosage of medications and taking them under the supervision of the attending physician. Uncontrolled intake of bismuth-containing drugs is unacceptable. In production, the best prevention of heavy metal poisoning is the strict observance of labor protection and safety requirements when working with toxic substances.

DEFINITION

Bismuth- the eighty third element of the Periodic table. Designation - Bi from the Latin "bismuthum". Located in the sixth period, VA group. Refers to metals. The core charge is 83.

Bismuth is a rare element in nature: its content in the earth's crust is 0.00002% (mass). In nature, it occurs both in a free state and in the form of compounds - bismuth ocher Bi 2 O 3 and bismuth luster Bi 2 S 3.

In the free state, bismuth is a shiny pinkish-white brittle metal with a density of 9.8 g / cm 3 (Fig. 1). Brittle. Melting point - 271.4 o C, boiling point - 1552 o C. At room temperature in air, bismuth does not undergo oxidation.

Rice. 1. Bismuth. Appearance.

Atomic and molecular weight of bismuth

The relative molecular mass of a 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 the relative atomic mass of an element (Ar r) is how many times the average mass of atoms of a chemical element is greater than 1/12 the mass of a carbon atom.

Since bismuth exists in the free state in the form of monatomic Bi molecules, the values ​​of its atomic and molecular masses coincide. They are equal to 208.9804.

Isotopes of bismuth

It is known that bismuth can occur in nature as the only stable isotope 209Bi. The mass number is 209, the nucleus of an atom contains eighty-three protons and one hundred and twenty-six neutrons.

There are artificial unstable isotopes of bismuth with mass numbers from 184 to 218, as well as more than ten isomeric states of nuclei.

Bismuth ions

On the outer energy level of the bismuth atom, there are five electrons that are valence:

1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 4f 14 5s 2 5p 6 5d 10 6s 2 6p 3 .

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

Bi 0 -3e → Bi 3+;

Bi 0 -5e → Bi 5+.

Bismuth molecule and atom

In the free state, bismuth exists in the form of monatomic Bi molecules. Here are some properties that characterize the atom and molecule of bismuth:

Bismuth alloys

Bismuth forms fusible alloys with other elements; for example, an alloy of bismuth with lead, tin and cadmium melts at 70 o C. These alloys are used in particular in automatic fire extinguishers, the operation of which is based on the melting of a plug made from such an alloy. In addition, they are used as solders.

Examples of problem solving

EXAMPLE 1

EXAMPLE 2

Exercise	Calculate the mass fractions of the elements that make up bismuth (III) oxide if its molecular formula is Ce 2 O 3.
Solution	The mass fraction of an element in the composition of any molecule is determined by the formula: ω (X) = n × Ar (X) / Mr (HX) × 100%.