Indicated by the sign Pt.

History of platinum

The ancient world already knew the metal platinum. During archaeological excavations in Egypt, in the ruins of ancient Thebes, an artistic case was found, attributed by experts to the 7th century BC. BC e. This relic of the ancient world contained a grain of iridium-rich platinum.

At the beginning of the 1st century n. e. gold-sand panners in Spain and Portugal began to show a marked interest in the beneficial use of "white lead", or "white gold", as platinum was then called. According to the Roman writer Pliny the Elder (author of the 37-volume book "Natural History"), "white lead" was mined from the gold placers of Valissia (Northwestern Spain) and Lusitania (Portugal). Pliny tells that the "white lead" was collected during washing along with gold at the bottom of the baskets and melted separately.

Long before the capture of South America by the Spanish and Portuguese conquistadors, platinum was mined by the cultural native people - the Incas, who not only owned the secret of cleaning and forging this precious metal, but also knew how to skillfully make various objects and jewelry from it.

The era of the fall of the Roman Empire is marked by the disappearance of jewelers and platinum jewelry dealers. Many centuries passed, and only in the second half of the XVIII century. scientists began to be interested in platinum and its physico-chemical properties.

In 1735, the Spanish mathematician Antonio de Ulloa, while in Equatorial Colombia, drew attention to the frequent presence, together with gold, of an unknown metal, the brilliance of which somewhat resembled the brilliance of silver, but in all other qualities more like gold. This outlandish metal interested de Ulloa, and he brought samples of Colombian platinum to Spain.

In the 18th century, when platinum did not yet have an industrial use, it was mixed with gold and with gold and silver products. The Spanish government learned about this "damage" to precious metals. Fearing the possibility of mass forgery of the gold coin, it decided to destroy all platinum mined together with gold in the kingdom's colonial possessions. In 1735, a decree was issued ordering the destruction of all platinum mined in Colombia. This decree was in effect for several decades. Special officials, in the presence of witnesses, periodically threw cash stocks of platinum into the river.

At the end of the XVIII century. the Spanish kings themselves began to "spoil" the gold coin, mixing platinum with it.

Technical uses of platinum

In 1752, the director of the Swedish mint, Schaeffer, announced the discovery of a new chemical element - platinum. Companions of platinum - palladium, iridium, rhodium, ruthenium and osmium - were discovered much later, in the 19th century. The six listed chemical elements, which are in the eighth group of the periodic system of Mendeleev, make up a group called platinum metals. All these metals have many similar physical and chemical properties and are mostly found together in nature.

At the dawn of the introduction of platinum into technology, scientists dealt with it mostly out of curiosity, but as the properties of platinum were studied in depth, it quickly began to find wide application, especially in the chemical industry. It turned out that platinum is soluble only in aqua regia, insoluble in acids and constant when heated.

Following the appearance of the first samples of chemical glassware made of platinum, it began to be used for the manufacture of distillation apparatus for sulfuric acid. From that moment on, the growth of platinum processing began to increase sharply, since it began to be used in the production of acid-resistant and heat-resistant laboratory chemical equipment, tools and various devices (crucibles, flasks, boilers, tongs, etc.).

Pyrometry uses the exceptional resistance of platinum and its alloys to high temperatures.

Valuable and sometimes indispensable properties of platinum and palladium have long been used in catalytic processes. A significant amount of platinum is spent on the manufacture of contacts for sulfuric acid plants, where it serves as a catalyst in the oxidation of sulfur dioxide to sulfuric anhydride. Platinum in the form of a grid serves as a catalyst for the oxidation of ammonia in apparatuses of various systems. Numerous organic syntheses also require the use of a platinum catalyst. The palladium catalyst is used in the production of synthetic ammonia and in the production of some organic preparations. Osmium is also used in the production of synthetic ammonia according to Haber-Rosennel.

In electrical engineering, platinum metals are usually used in the form of alloys. Here is a far from complete list of parts of electrical devices where platinum alloys are used: needles for burning, devices for electrical measurements, electrodes (cathodes and anticathodes for X-ray tubes), wires and tapes for electric furnace resistances, magneto contacts (cars, internal combustion engines), contact points (telegraphy, telephony), lightning rod tips, etc.

In electrochemistry, platinum is used in the preparation of various electrolytic products. Medicine and dentistry are among the oldest consumers of platinum. We also note the use of platinum for surgery in the form of tips for devices used for cauterization, syringes for injection and infusion, etc.

The art of jewelery occupies a leading position as a consumer of platinum in the form of alloys. Platinum gemstone settings give better brilliance and cleaner water than other precious metal settings.

Finally, in the form of salts, platinum and its companions are required for photography, for the manufacture of medicines (salts of rhodium and ruthenium) and for the preparation of paints on porcelain (rhodium, iridium - black paint, palladium - silver).

Platinum is also used in the military, for example, for the manufacture of contacts that serve to produce detonation during the explosion of mines, etc.

Application of platinum

Platinum mining

The first place in the world production of platinum belongs to the Ontario region in Canada. Here, in 1856, large deposits of copper-nickel ores of Sudbury were discovered, in which, along with gold and silver, platinum is also present.

Before the First World War, Canadian platinum did not attract attention, and practical interest in it arose only in 1919, when, as a result of the civil war in the Urals, the extraction of Russian platinum fell sharply, and the world market began to feel a great shortage of this valuable metal. Since 1919, the sludge from the copper-nickel production of Sudbury began to be subjected to thorough processing in order to extract platinum group metals, especially since the cost of associated mining of platinum and its satellites is very low.

Russia occupies the second place in the world in platinum mining. Significant amounts of platinum are mined in Colombia. Other platinum-producing countries include Ethiopia and the Congo. Platinum mined directly from the depths, as well as platinum obtained from ores, is subjected to special processing or refining. Refining consists of the usual processes used on a small scale in the practice of analytical laboratories - dissolution, evaporation, filtration, precipitation, etc. As a result of these operations, pure platinum and separately its satellites are obtained.

Platinum mining

Platinum deposits in Russia

The main platinum-bearing province of the Urals is the western zone of deep igneous rocks, continuously traced for 300 km in the region of the Middle Urals. Platinum deposits in this zone are associated mainly with igneous rocks. During the weathering and destruction of these rocks and when the weathering products are washed away by rivers, pure platinum placers are formed, which are an exceptional feature of the Urals and have provided the bulk of the platinum mined so far.

In the region of the eastern zone of deep igneous rocks there are a number of less valuable deposits of platinum. Here platinum occurs together with gold and osmium iridium. Due to the destruction and erosion of these rocks, mixed gold-platinum and gold-osmite-iridium-platinum placers are formed, which are less valuable from the point of view of the extraction of platinum, which is here only an admixture to gold.

Ural platinum before the war of 1914-1918. ranked first in the world market. In the first half of the XIX century. (from 1828 to 1839) a coin was minted from Ural platinum in Russia. However, the minting of such a coin was discontinued due to the instability of the exchange rate for platinum and the importation of counterfeit coins into Russia.

Despite the fact that in Russia platinum refining began immediately after the discovery of platinum deposits in the Urals. before the revolution, the amount of platinum processed in our country was only 10-13% of the mined metal. Most of the crude platinum and refining intermediates were exported abroad.

There has been a refinery in Moscow for more than 100 years, where they are engaged in the mechanical processing of refined platinum and alloys. It also produces forging, rolling, wire drawing, manufacturing of chemical glassware, grids of electrodes, contacts, pyrometers, electric heaters and other products.

Moscow Refinery

Platinum, Platinum, Pt (78)

Platinum (English Platinum, French Platine, German Platin) was probably known in antiquity. The first description of platinum as a highly fire-resistant metal, which can only be melted with the help of "Spanish art", was made by the Italian physician Scalinger in 1557. Apparently, at the same time the metal received its name "platinum". It displays a dismissive attitude towards metal, as there is little to anything suitable and not amenable to processing. The word "platinum" comes from the Spanish name for silver - board (Plata) and is a diminutive form of this word, which in Russian sounds like silver, silver (according to Mendeleev - silver). It is interesting to note that the word platinum is consonant with the Russian "fee" (pay, payment, etc.) and is close to it in meaning. In the 17th century platinum was called Platina del Pinto, because it was mined in the golden sand of the Pinto River in South America; there was another name of this kind - Platina del Tinto from the Rio del Tinto river in Andalusia. Platinum was described in more detail in 1748 by de Walloa, a Spanish mathematician, navigator and merchant. Starting from the second half of the XVIII century. Many analytical chemists and technologists, including scientists from the St. Petersburg Academy of Sciences, became interested in platinum, its properties, methods of processing and use. The most important work in this area in the first half of the 19th century was the creation of methods for obtaining malleable platinum (Sobolevsky, Wollaston, and others), the discovery of some of its compounds (Musin-Pushkin, and others) and platinum group metals.

- an infinite set of all objects and systems coexisting in the world, the totality of their properties and connections, relations and forms of movement. It includes not only directly observed objects and bodies of nature, but also all those that are not given to man in his sensations.

Movement is an essential property of matter. The motion of matter is any change that occurs with material objects as a result of their interactions. In nature, various types of motion of matter are observed: mechanical, oscillatory and wave, thermal motion of atoms and molecules, equilibrium and non-equilibrium processes, radioactive decay, chemical and nuclear reactions, the development of living organisms and the biosphere.

At the present stage of development of natural science, researchers distinguish the following types of matter: matter, physical field and physical vacuum.

Substance is the main type of matter that has a rest mass. Material objects include: elementary particles, atoms, molecules and numerous material objects formed from them. The properties of a substance depend on external conditions and the intensity of the interaction of atoms and molecules, which determines the various aggregate states of substances.

physical field is a special kind of matter that provides the physical interaction of material objects and their systems. Researchers refer to physical fields: electromagnetic and gravitational fields, the field of nuclear forces, wave fields corresponding to various particles. Particles are the source of physical fields.

physical vacuum is the lowest energy state of the quantum field. This term was introduced into quantum field theory to explain certain processes. The average number of particles - field quanta - in vacuum is equal to zero, but particles in intermediate states that exist for a short time can be born in it.

When describing material systems, corpuscular (from lat. corpusculum- particle) and continuum (from lat. continuous– continuous) theory. Continuum the theory considers repetitive continuous processes, fluctuations that occur in the vicinity of a certain average position. When vibrations propagate in a medium, waves arise. The theory of oscillations is a branch of physics that studies these regularities. Thus, the continuum theory describes wave processes. Along with the wave (continuum) description, the concept of a particle - corpuscles is widely used. From point of view continuous concept, all matter was considered as a form of a field uniformly distributed in space, and after a random perturbation of the field, waves arose, that is, particles with different properties. The interaction of these formations led to the appearance of atoms, molecules, macrobodies, forming the macroworld. On the basis of this criterion, the following levels of matter are distinguished: microcosm, macrocosm and megaworld.

The microcosm is a region of extremely small, directly unobservable material micro-objects, the size of which is calculated in the range from 10 -8 to 10 -16 cm, and the lifetime is from infinity to 10 -24 s. This is the world from atoms to elementary particles. All of them have both wave and corpuscular properties.

Macroworld- the world of material objects, commensurate in scale with a person. At this level, spatial quantities are measured from millimeters to kilometers, and time from seconds to years. The macrocosm is represented by macromolecules, substances in various states of aggregation, living organisms, man and the products of his activity.

Megaworld- a sphere of huge cosmic scales and velocities, the distance in which is measured in astronomical units (1 AU \u003d 8.3 light minutes), light years (1 light year \u003d 10 trillion km) and parsecs (1pc \u003d 30 trillion km), and the time of existence of space objects - millions and billions of years. This level includes the largest material objects: planets and their systems, stars, galaxies and their clusters forming metagalaxies.

Classification of elementary particles

Elementary particles are the main structural elements of the microworld. Elementary particles can be constituent(proton, neutron) and non-composite(electron, neutrino, photon). To date, more than 400 particles and their antiparticles have been discovered. Some elementary particles have unusual properties. Thus, for a long time it was believed that the neutrino particle has no rest mass. In the 30s. 20th century when studying beta decay, it was found that the energy distribution of electrons emitted by radioactive nuclei occurs continuously. It followed from this that either the law of conservation of energy is not fulfilled, or, in addition to electrons, difficult-to-detect particles are emitted, similar to photons with zero rest mass, which carry away part of the energy. Scientists have suggested that this is a neutrino. However, experimental registration of neutrinos was possible only in 1956 at huge underground installations. The difficulty of registering these particles lies in the fact that the capture of neutrino particles is extremely rare due to their high penetrating power. During the experiments, it was found that the rest mass of the neutrino is not equal to zero, although it does not differ much from zero. Antiparticles also have interesting properties. They have many of the same features as their twin particles (mass, spin, lifetime, etc.), but differ from them in terms of electric charge or other characteristics.

In 1928, P. Dirac predicted the existence of an antiparticle of the electron - the positron, which was discovered four years later by K. Anderson as part of cosmic rays. An electron and a positron are not the only pair of twin particles; all elementary particles, except for neutral ones, have their own antiparticles. When a particle and an antiparticle collide, they annihilate (from lat. annihilatio- transformation into nothing) - the transformation of elementary particles and antiparticles into other particles, the number and type of which are determined by conservation laws. For example, as a result of the annihilation of an electron-positron pair, photons are born. The number of detected elementary particles increases with time. At the same time, the search for fundamental particles continues, which could be composite "building blocks" for building known particles. The hypothesis about the existence of this kind of particles, called quarks, was put forward in 1964 by the American physicist M. Gell-Man (Nobel Prize in 1969).

Elementary particles have a large number of characteristics. One of the distinguishing features of quarks is that they have fractional electric charges. Quarks can combine with each other in pairs and triplets. The union of three quarks forms baryons(protons and neutrons). Quarks were not observed in the free state. However, the quark model made it possible to determine the quantum numbers of many elementary particles.

Elementary particles are classified according to the following features: particle mass, electric charge, type of physical interaction in which elementary particles participate, particle lifetime, spin, etc.

Depending on the rest mass of the particle (its rest mass, which is determined in relation to the rest mass of the electron, which is considered the lightest of all particles having mass), they distinguish:

photos- particles that have no rest mass and move at the speed of light);

leptos– light) – light particles (electron and neutrino);

mesos- medium) - medium particles with a mass from one to a thousand masses of an electron (pi-meson, ka-meson, etc.);

barys- heavy) - heavy particles with a mass of more than a thousand masses of an electron (protons, neutrons, etc.).

Depending on the electric charge, there are:

There are particles with a fractional charge - quarks. Taking into account the type of fundamental interaction in which particles participate, among them are:

adros- large, strong), participating in electromagnetic, strong and weak interaction;

are carriers of the strong interaction; intermediate vector bosons - carriers of the weak interaction).

According to the lifetime of the particles are divided into stable, quasi-stable and unstable. Most elementary particles are unstable, their lifetime is 10 -10 -10 -24 s. Stable particles do not decay for a long time. They can exist from infinity to 10 -10 s. The photon, neutrino, proton and electron are considered stable particles. Quasi-stable particles decay as a result of electromagnetic and weak interaction, otherwise they are called resonances. Their lifetime is 10 -24 -10 -26 s.

Most people can easily name the three classical states of matter: liquid, solid, and gaseous. Those with even the slightest interest in physics would add plasma to this list. But in fact, today scientists have significantly expanded the list of possible states of matter. Today there are at least ten of them.

1. Amorphous bodies

Amorphous solids are an unusual subset of the known solid state of matter. In an ordinary solid object, the molecules are highly organized and cannot move freely. This gives the solid a high viscosity, which is a measure of resistance. And in a liquid, on the contrary, the molecular structure is disorganized, which allows the molecules to move freely, and the liquid to take the shape of the vessel into which it is poured.

An amorphous solid is halfway between these two states of matter. During a process known as vitrification, the liquid cools and its viscosity rises to such an extent that it no longer flows like a liquid, but its molecules remain disordered and do not form a crystalline structure like a normal solid. The most common example of an amorphous solid is glass.

2. Supercritical fluids

Most phase transitions from one state to another occur at certain temperatures and pressures. It is common knowledge that an increase in temperature eventually turns a liquid into a gas. However, when the pressure increases along with the temperature, the liquid instead goes into a supercritical state, which has the properties of both a gas and a liquid. For example, supercritical fluids can pass through solids like a gas, but can also act as a solvent like a liquid. Interestingly, a supercritical fluid can have most of the properties of a gas or liquid, depending on the combination of pressure and temperature.

3. Degenerate matter

Amorphous solids exist even on planet Earth, and degenerate matter can only exist in certain types of stars. Such matter exists when its shape and stability are dictated not by temperature, as on Earth, but by complex quantum principles, like the Pauli principle. Because of this, the shape of the degenerate matter will be preserved even if the temperature of the matter drops to absolute zero.

Two main types of degenerate matter are known: electron-degenerate matter and neutron-degenerate matter. Electron-degenerate matter exists mainly in white dwarf stars, provided that the star's mass is 1.44 times less than the mass of our Sun. If a star is more massive than this limit (known as the Chandrasekhar limit), it will simply collapse into a neutron star or black hole. And in a black hole, matter is converted into a neutron-degenerate form. Free neutrons (not bound in the atomic nucleus) typically have a half-life of 10.3 minutes, but in the core of a neutron star, neutrons exist outside the core, forming neutron-degenerate matter.

4. Superfluid matter

From distant stars, let's go back to the Earth to discuss superfluidity. Superfluid - A state of matter that exists when certain isotopes of helium, rubidium, and lithium are cooled to near absolute zero. The most common is superfluid liquid helium. When helium is cooled to the so-called lambda "point" - 2.17 degrees Kelvin, then part of the liquid becomes superfluid. In this case, helium atoms interact with each other so that it can remain liquid up to absolute zero.

Also, the substance in this state has very strange properties. A superfluid liquid placed in a test tube begins to creep up the sides of the test tube, seemingly violating the laws of gravity and surface tension. At the same time, liquid helium is incredibly difficult to keep, since it seeps through the smallest pores. For example, from a standard thermos, it will "mysteriously disappear" in just a few minutes.

5. Bose-Einstein condensate

The Bose-Einstein condensate is probably one of the most unexplored and difficult to understand forms of matter. First, you need to understand what bosons and fermions are. Fermions are particles with a half-integer spin, such as quarks and leptons. These particles obey the Pauli principle, with the help of which an electronically degenerate substance is formed.

A boson is a particle with an integer spin, and several bosons can take on the same quantum state. Bosons include any particles with an energy charge (for example, photons). In the 1920s, Albert Einstein, based on the work of the Indian physicist Bose, suggested the existence of a new form of matter based on bosons cooled to temperatures close to absolute zero. (less than a millionth of a degree above absolute zero).

Bose-Einstein condensates are very similar to superfluid matter, but have their own unique properties. The most shocking thing is that the BEC can slow down the speed of light from its normal speed of 300,000 meters per second. In 1998, Harvard researcher Lene Howe was able to slow light down to as little as 60 kilometers per hour by firing a laser beam through a cigar-shaped BEC sample. In a later experiment, Howe's team was able to completely stop the light in the BEC.

6. Jahn-Teller metal

Researchers managed to successfully create such a substance only in 2015. If their experiments are confirmed by other laboratories, then this could change the world, since the Jahn-Teller metal has the properties of both an insulator and a superconductor at the same time. In the metal, which was named after the Jahn-Teller effect, pressure can transform the geometry of molecules into new electronic configurations. Simply put, the resulting substance can easily change its state into a conductor, insulator, metal, and magnetic material. The properties of such a material change depending on the distance between the atoms in the crystal lattice. The distance is changed with the help of pressure, but not the usual mechanical, but chemical.

7. Photon matter

For many decades it was believed that photons are massless particles that do not interact with each other. However, in the past few years, researchers have discovered new ways to give light mass and have even created "light molecules" that bounce off each other and form bonds with each other. This is, in fact, the first step towards creating a Star Wars lightsaber.

8. Disordered hyperhomogeneity

When trying to translate a substance into a new state of matter, scientists look at the structure of the substance, as well as its properties. In 2003, Salvatore Torquato and Frank Stillinger at Princeton University proposed a new state of matter called disordered hyperhomogeneity. Most interestingly, they discovered a new state of matter after carefully studying the eye of a chicken.

It turned out that the cells in the retina of a chicken eye are arranged randomly, but at the same time evenly. A substance in such a state exhibits the properties of a liquid and a crystal at the same time. It would seem that this is possible only in the state of plasma, but nature turned out to be more cunning. It is assumed that such a discovery can help in the development of fundamentally innovative devices for transmitting light.

9. String-net fluid

What is the state of matter in the vacuum of space? Most people have not thought about this question, but in the last decade, MIT scientists Xiao Gang-Wen Jiabao and Harvard Michael Levin have proposed a hypothetical new state of matter that could hold the key to the discovery of fundamental particles smaller than the electron.

Back in the mid-90s, a group of scientists announced the possibility of the existence of so-called "quasi-particles", since during the experiment, electrons passed between two semiconductors. This caused quite a stir, since the quasiparticles acted as if they had a fractional charge, which was considered impossible in physics. Based on this data, the team suggested that the electron is not a fundamental particle in the universe, and that there are more fundamental particles that people have not yet discovered. Their work won a Nobel Prize, but it was later discovered that the results were due to an error in the experiment.

The idea of ​​"quasi-particles" was refuted. But some researchers have not abandoned it completely. Wen Jiabao and Levin continued their work on "quasi-particles" and proposed the existence of a new state of matter known as a string-net fluid, the main property of which is quantum entanglement. In their papers, Wen Jiabao and Levin stated that the cosmos is filled with string networks of entangled subatomic particles.

10. Quark-gluon plasma

Initially, the Universe was in a completely different state of matter than it is now. It is believed that there are no free quarks in nature, but immediately after the Big Bang, free quarks and gluons existed for a millisecond. During this time, the temperature of the universe was so high that quarks and gluons interacted with each other.

During this period of time, the Universe consisted entirely of hot quark-gluon plasma. Quark-gluon plasma is a state of matter in which released colored quarks and gluons form a continuous medium (chromoplasm), and can also propagate in it as quasi-free particles. There is a so-called "color conductivity", which is similar to the electrical conductivity that occurs in a conventional electron-ion plasma.

One of the recent discoveries is in the constellation Cygnus.

The objects of study of physical science are matter, its properties and structural forms, which form the world around us. According to the ideas of modern physics there are two types of matter: matter and field. Substance - a kind of matter, consisting of fundamental particles with mass. The smallest particle of a substance that has all its properties - a molecule - consists of atoms. For example, a water molecule is made up of two hydrogen atoms and one oxygen atom. What are atoms made of? Every atom consists of a positively charged nucleus and negatively charged electrons moving around it (Fig. 21.1).

Electron size up to

In turn, nuclei are made up of protons and neutrons.

You can ask the following question. What are protons and neutrons made of? The answer is known - from quarks. And the electron? Modern means of studying the structure of particles do not allow answering this question.

The field as a physical reality (i.e., a type of matter) was first introduced by M. Faraday. He suggested that the interaction between physical bodies is carried out through a special kind of matter, which was called the field.

Any physical field provides a certain type of interaction between the particles of matter. Found in nature four main types of interaction: electromagnetic, gravitational, strong and weak.

Electromagnetic interaction is observed between charged particles. In this case, attraction and repulsion are possible.

Gravitational interaction, the main manifestation of which is the law of universal gravitation, is expressed in the attraction of bodies.

The strong force is the interaction between hadrons. The radius of its action is of the order of m, i.e., of the order of the dimensions of the nucleus of an atom.

Finally, the last interaction is the weak interaction, through which such an elusive particle as the neutrino reacts with matter. In flight through outer space, colliding with the Earth, it pierces it through and through. An example of a process in which a weak interaction is manifested is the beta decay of a neutron.

All fields have mass equal to zero. A feature of the field is the permeability to other fields and matter. The field obeys the principle of superposition. Fields of the same type, when superimposed, can strengthen or weaken each other, which is impossible for matter.

Classical particles (material points) and continuous physical fields - these are the elements that made up the physical picture of the world in the classical theory. However, such a dual picture of the structure of matter turned out to be short-lived: matter and field are combined into a single concept of a quantum field. Every particle is now a quantum of the field, a special state of the field. In quantum field theory there is no fundamental difference between a vacuum and a particle, the difference between them is the difference between two states of the same physical reality. Quantum field theory clearly shows why space is impossible without matter: "emptiness" is just a special state of matter, and space is a form of existence of matter.

Thus, the division of matter into field and substance as into two types of matter is conditional and justified within the framework of classical physics.