Field and substance as types of existence of matter. The concept of matter. Types and properties of matter. Engels proposed the forms of movement

Department of Applied Mathematics

TEST

in the discipline "Concepts modern natural science»

on the topic of:
« Matter. Matter types»

Arkhangelsk
2010
Content

Introduction ............................................................... .................................... ................. .............................................. .3
1. The concept of matter ………….…………………………………………………………….. ………..5
2. Types of matter ……………………………………………………………………………… ……. eight
2.1. Substance ……………………………………………………………………………. .……….. 10
2.2. Physical field …………………………………………………………………….……… .. 11
2.3. Physical vacuum…………………………………………………….……… .…….………. 12
2.4. Time………………………………………………………………… …………………..……. thirteen
2.5. Space……………………………………………………………………………….….….14
3. The concept of atomism. Discreteness and continuity of matter………………….…….…… 15
Conclusion.................... ............................. . ............................. ................... ......................................17
List of references……………………………………………………………………………………………… ... .............................. .........eighteen

Introduction

The problem of determining the essence of matter is very complex. The complexity lies in the high degree of abstractness of the very concept of matter, as well as in the variety of different material objects, forms of matter, its properties and interdependencies. In this regard, philosophy and other sciences face many questions: What is matter? How did ideas about her develop? How to correlate with the concept of matter an infinite number of specific objects, things? What properties does it have? Is matter eternal and infinite? What is the reason for its change? What types of matter are currently known? How is the mutual transition of some types of matter and forms of its motion to others carried out? On the basis of what laws does this happen?
The material world surrounding a person represents an infinite number of objects and phenomena that have the most diverse properties. Despite the differences, they all have two important features:
1) they all exist independently of human consciousness;
2) are able to influence a person, be reflected by our consciousness.
In pre-Marxist philosophy, various conceptions of matter developed: atomistic (Democritus), ethereal (Descartes), material (Holbach). "... Matter in general is everything that somehow affects our feelings" (Holbach "The System of Nature"). Common to all concepts was the identification of matter with its specific types and properties, or with the atom, as one of the simplest particles underlying the structure of matter.
In developing the scientific definition of matter, K. Marx and F. Engels had in mind the objective world as a whole, the totality of its constituent bodies. Based on the dialectical and historical materialism of Marx and Engels, V.I. Lenin further developed this doctrine, formulating the concept of matter in his work "Materialism and Empiriocriticism": "Matter is a philosophical category for designating objective reality, which is given to a person in his sensations, which is copied, photographed, displayed by our sensations, existing independently of them."
From the philosophical concept of matter it is necessary to distinguish natural-science and social ideas about its types, structure and properties. Philosophical understanding of matter reflects the objective reality of the world, while natural-science and social representations express its physical, chemical, biological, and social properties. Matter is the objective world as a whole, and not what it consists of. Separate objects, phenomena do not consist of matter, they act as specific types of its existence, such as, for example, inanimate, living and socially organized matter, elementary parts, cells, living organisms, production relations, etc. All these forms of the existence of matter are studied by various natural, social and technical sciences.
The purpose of this work is to consider the concept of "matter" and consider its types.

1. The concept of matter

Matter - it is all that directly or indirectly affects the human senses and other objects. The world around us, everything that exists around us and is detected directly or indirectly through our sensations is a matter that is identical to reality. An integral property of matter is motion. Without movement there is no matter and vice versa. Matter movement - any changes that occur to material objects as a result of their interactions. Matter does not exist in a formless state - a complex hierarchical system of material objects of various scales and complexity is formed from it.
Matter has many properties, the most common of which are:

movement, space and time, which are attributes of matter, i.e. that which ensures their existence.
Matter is eternal and infinite. This means that it never had a beginning in time and space and will never have an end.
The principle of indestructibility and increatibility of matter and motion is the next property of matter. This principle is concretely realized in numerous conservation laws.
An important property of matter is the ability to interconvert different types of matter into each other. It follows from this that certain types of matter can disappear, but at the same time, other types of matter appear in a certain quantitative ratio. And this process is endless.
Finally, matter is characterized by inconsistency, the unity of the discontinuous and the continuous, the unity of the finite and the infinite, absoluteness and relativity, and so on.

Three main types of matter should be distinguished, which include matter, antimatter and field. Electromagnetic, gravitational, electronic, meson and other fields are known. Substance includes elementary particles (excluding photons), atoms, molecules, macro- and mega-bodies, i.e. everything that has a mass of rest. All these types of matter are dialectically interconnected. An illustration of this is the discovery in 1922 by Louis de Broglie of the dual nature elementary particles, which in some conditions reveal their corpuscular nature, and in others - wave qualities.
In the most general form, the following structural levels of matter can be distinguished:

Elementary particles and fields;
Atomic-molecular level;
All macro-objects, liquids and gases;
Space objects: galaxies, stellar associations, nebulae, etc.;
Biological level, wildlife;
The social level is society.

Each structural level of matter in its movement, development is subject to its own specific laws. So, for example, at the first structural level, the properties of elementary particles and fields are described by the laws of quantum physics, which are of a probabilistic, statistical nature. Their laws operate in wildlife. Human society operates according to special laws. There are a number of laws that operate at all structural levels of matter (the laws of dialectics, the law of universal gravitation, etc.), which is one of the evidence of the inseparable interconnection of all these levels.

A higher level of matter includes its lower levels. For example, atoms and molecules include elementary particles, macrobodies consist of elementary particles, atoms and molecules. However, material formations for more high level are not just a mechanical sum of lower level elements. These are qualitatively new material formations, with properties that are fundamentally different from the simple sum of the properties of the constituent elements, which is reflected in the specifics of the laws that describe them. It is known that an atom consisting of heterogeneously charged particles is neutral. Or a classic example. Oxygen supports combustion, hydrogen burns, and water, whose molecules are composed of oxygen and hydrogen, extinguishes fire. Further. Society is a collection of individuals - biosocial beings. At the same time, society is not reducible either to an individual person or to a certain sum of people.

3. Based on the above classification, three different spheres of matter can be distinguished: inanimate, living and socially organized - society. Above, these spheres were considered in a different plane. The fact is that any classification is relative, and therefore, depending on the needs of knowledge, it is possible to give a very different classification of levels, spheres, etc., reflecting the complex, multifaceted structure of matter. We emphasize that the selected one or another basis of classification is only a reflection of the diversity of objective reality itself. It is possible to allocate micro-, macro- and mega-world. This classification of the structure of matter is not exhausted, and other approaches to it are possible.

The main feature of natural science knowledge is that for natural scientists it is not matter or movement in general that is of interest, but specific types of matter and movement, the properties of material objects, their characteristics that can be measured using instruments. In modern natural science, three types of matter are distinguished: matter, physical field and physical vacuum.
It is customary to consider time and space as universal universal forms of existence and movement of matter. The movement of material objects and various real processes occur in space and time. A feature of the natural-science concept of these concepts is that time and space can be characterized quantitatively with the help of instruments.
The special theory of relativity unified space and time into a single space-time continuum. The basis for such a union is the principle of relativity and the postulate of the limiting speed of transmission of interactions of material objects - the speed of light in vacuum, approximately equal to 300,000 km/s. From this theory follows the relativity of the simultaneity of two events that occurred at different points in space, as well as the relativity of measurements of lengths and time intervals made in different frames of reference, moving relative to each other.
In accordance with the general theory of relativity, the properties of space - time depend on the presence of material objects. Any material object bends space, which can be described not by Euclid's geometry, but by Riemann's spherical geometry or Lobachevsky's hyperbolic geometry. It is assumed that around a massive body at a very high density of matter, the curvature becomes so large that space-time, as it were, "closes" locally on itself, separating this body from the rest of the Universe and forming a black hole that absorbs material objects and electromagnetic radiation. On the surface of a black hole, for external observation, time seems to stop. It is assumed that at the center of our galaxy is a huge black hole. However, there is another point of view. Academician of the Russian Academy of Sciences A. A. Logunov claims that there is no curvature of space - time, but there is a curvature of the trajectory of the movement of objects, due to a change in the gravitational field. In his opinion, the observed redshift in the radiation spectrum of distant galaxies can be explained not by the expansion of the Universe, but by the transition of the radiation they send from a medium with a strong gravitational field to a medium with a weak gravitational field, in which the observer on Earth is located.

2.1. Substance

Substance - the main type of matter that has mass. Material objects include elementary particles, atoms, molecules and numerous material objects formed from them. In chemistry, substances are divided into simple (with atoms of one chemical element) and complex - chemical compounds. The properties of a substance depend on the external conditions and the intensity of the interaction of its constituent atoms and molecules, which determines the various aggregate states of the substance: solid, liquid and gaseous. At a relatively high temperature, a plasma state of matter is formed. The transition of matter from one state to another can be considered as one of the types of motion of matter.
In nature, various types of motion of matter are observed, which can be classified taking into account changes in the properties of material objects and their effects on the surrounding world. Mechanical motion (relative movement of bodies), oscillatory and wave motion, distribution and change of various fields, thermal (chaotic) motion of atoms and molecules, equilibrium and non-equilibrium processes in macrosystems, phase transitions between various aggregate states (melting, vaporization, etc.), radioactive decay, chemical and nuclear reactions, the development of living organisms and the biosphere, the evolution of stars, galaxies and the universe as a whole - all these are examples of the diverse types of motion of matter.

2.2. physical field

physical field - a special kind of matter that provides the physical interaction of material objects and their systems. Physical fields include electromagnetic and gravitational fields, the field of nuclear forces, as well as wave (quantum) fields corresponding to various particles (for example, the electron-positron field). The source of physical fields are particles (for example, for an electromagnetic field - charged particles). The physical fields created by the particles transfer the interaction between them with a finite speed. In quantum theory, interaction is determined by the exchange of field quanta between particles.

2.3. physical vacuum

physical vacuum - the lowest energy state of the quantum field. This term was introduced in quantum field theory to explain some microprocesses. The average number of particles - field quanta - in vacuum is equal to zero, but virtual particles can be born in it - particles in intermediate states that exist for a short time. Virtual particles affect physical processes. Particle - antiparticle pairs of various types can be born in the physical vacuum. At a sufficiently high concentration of energy, the vacuum interacts with real particles, which is confirmed by experiment. It is assumed that the universe was born from the physical vacuum, which is in an excited state.

2.4. Time

Time expresses the order of change of physical states and is an objective characteristic of any process or phenomenon. Time is something that can be measured with a watch. The principle of clock operation is based on many physical processes, among which the most convenient are periodic processes: the rotation of the Earth around its axis, the electromagnetic radiation of excited atoms, etc. Many major achievements in natural science are associated with the development of more accurate clocks. Standards that exist today make it possible to measure time with very high accuracy - the relative measurement error is about 10 -11 .
The time characteristic of real processes is based on postulate of time: phenomena that are the same in all respects occur in the same time. Although the postulate of time seems natural and obvious, its truth is still relative, since it cannot be verified experimentally even with the help of the most advanced clocks, since, firstly, they are characterized by their accuracy and, secondly, it is impossible to create fundamentally identical conditions in nature at different times. At the same time, the long-term practice of natural-science research makes it possible to have no doubts about the validity of the postulate of time within the limits of the accuracy that has been achieved at a given moment in time.
When creating classical mechanics about 300 years ago, I. Newton introduced the concept of absolute, or true, mathematical time, which flows always and everywhere uniformly, and relative time as a measure of duration used in everyday life and meaning a certain interval of time: hour, day, month etc.
In the modern world, time is always relative. . From the theory of relativity it follows that at a speed close to the speed of light in a vacuum, time slows down - relativistic time dilation occurs , and that a strong gravitational field leads to gravitational time dilation . Under normal terrestrial conditions, such effects are extremely small.
The most important property of time is its irreversibility. The past in all details and details cannot be reproduced in real life - the past is forgotten. The irreversibility of time is due to the complex interaction of many natural systems, including atoms and molecules, and is symbolically indicated by the arrow of time , " flying" always from the past to the future. The irreversibility of real processes in thermodynamics is associated with the chaotic movement of atoms and molecules.

2.5. Space

The concept of space is much more complex than the concept of time. Unlike one-dimensional time, real space is three-dimensional, i.e. has three dimensions. In three-dimensional space there are atoms and planetary systems, the fundamental laws of nature are fulfilled. However, hypotheses are put forward, according to which the space of our Universe has many dimensions, although of them our senses are able to feel only three.
The first ideas about space arose from the obvious existence in nature of solid bodies occupying a certain volume. Based on it, we can give a definition: space expresses the order of coexistence of physical bodies. The complete theory of space - the geometry of Euclid - was created more than 2000 years ago and is still considered a model of scientific theory.
By analogy with absolute time, I. Newton introduced the concept of absolute space, which exists independently of the physical objects located in it and can be completely empty, being, as it were, a world arena where physical processes are played out. The properties of space are determined by the geometry of Euclid. It is this idea of ​​space that underlies the practical activity of people. However, empty space is ideal, while the real world around us is filled with various material objects. An ideal space without material objects is meaningless even, for example, when describing the mechanical motion of a body, for which it is necessary to specify another body as a frame of reference. The mechanical motion of bodies is relative. Absolute motion, like absolute rest of bodies, does not exist in nature. Space, like time, is relative.

3. The concept of atomism. Discreteness and continuity of matter

Conclusion

Bibliography

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Karpenkov S.Kh. Modern natural science. - M.: Academic project, 2003.
Karpenkov S.Kh. Concepts of modern natural science. - M.: Culture and sport, UNITI, 1997.
Concepts of modern natural science. - St. Petersburg: Peter, 2008.
Concepts of modern natural science / Ed. V.N. Lavrinenko. - M.: Culture and sport, UNITI, 1997.
Modern natural science: Encyclopedia: In 10 volumes - M .: Publishing house MAGISTER-PRESS, 2000. - V.1. - Physical chemistry.
Philosophical understanding of the world / Ed. V.V. Terentiev. - M.: MIIT, 1994.

1) Substance- this is a physical form of matter, consisting of particles that have their own mass (rest mass)

2) Field– a material formation that connects bodies to each other and transfers action from body to body (electromagnetic, gravitational, intranuclear fields) A photon has no rest mass, because light is not at rest.

3) Antimatter- in-in, consisting of antiparticles. The structure of antimatter: the nuclei of atoms of this kind of physical reality must exist from antiprotons and antineutrons, and the shell from positrons.

The material world around us can be divided, firstly, into microcosm, macrocosm and megaworld, each of which, in turn, includes various levels of organization of material existence:

- in inanimate nature: 1) submicroelementary level (quarks), 2) elementary (electrons), 3) nuclear (atomic nucleus), 4) atomic, 5) molecular, 6) macroscopic, 7) planetary, 8) cosmic.

- in wildlife: 1) biological macromolecules, 2) cellular, 3) microorganism, 4) the level of organs and tissues, 5) the level of the organism, 6) population, 7) biocenosis, 8) biospheric.

- to social: 1) person (individual), 2) family, 3) collectives, 4) social groups, 5) nationalities, 6) ethnic groups, 7) states

Each of the structural levels (and sublevels) of matter arises and exists on the basis of the previous ones, but is not reduced to them as a simple sum of elements, since it has new qualities and obeys other laws in its functioning and development.

11. Movement, space, time as the main forms of existence of matter.

Motion- a concept that covers in the most general form any change, transformation. Everything that exists is in constant striving for change, another state, but only that which has relative stability and is in relative peace changes. But without a certain degree of stability in the world, nothing would exist. Rest is a relative concept, and movement is absolute. But, the movement also has the properties of relativity, because. changes to one object can only be fixed relative to another object.

Back in antiquity there were 2 concepts:

1) Zeno - negation of movement. Aporia of Zeno. Proved the impossibility of thinking movement.

2) Heraclitus - "Everything flows!" Everything is constantly moving from one state to another.

Engels proposed the following forms of movement:

Mechanical

Physical

Chemical

biological

Social

Types of motion of matter:

1) mechanical(no change in quality)

2) With quality change. Orientation is of 3 types:

Progressive (from lowest to highest)

Regressive (highest to lowest)

Horizontal (the phenomenon of idioadaptation in biology, changes depend on the conditions of existence and are not accompanied by a general increase in the organization and level of life. For example, the periodic table, where changes unfold at one horizontal structural level of the organization of matter)

Development is subject to a number of laws:

The law of transition from one quality to another based on quantitative changes

The law of unity and struggle of opposites

Law of negation of negation

No matter how the object changes, while it exists, it retains its certainty. A river does not cease to be a river because it flows: the being of a river lies in its flow. To find absolute peace means to cease to exist. Everything relatively at rest inevitably participates in some movement. Peace always has only a visible and relative character. Bodies can only be at rest with respect to any frame of reference conventionally accepted as motionless (For example, we are motionless relative to buildings, the Earth, but we move relative to the Sun)

Private spaces:

-three-dimensionality(any spatial relationship can be described by three dimensions - length, width, height)

-reversibility(you can return to the same place)

-length

-isotropy(equality of all possible directions)

Private times:

-one-dimensionality(one coordinate is enough: minute, hour, second)

-unidirectionality(can't go back in time)

General properties of space and time:

Objectivity (independence from our consciousness)

Infinity (there is no such place in the universe where space and time would be absent)

Absoluteness (i.e. being outside of space is the same nonsense as being outside of time)

Relativity (i.e., a person's ideas about space and time are relative)

Unity of continuity (absence of empty space)

Unity of discontinuity (separate existence of material objects)

Types of space and time:

-Real(objective forms of existence of pr-va and time)

-Perceptual(subjective human perception of real space and time)

-Conceptual(theoretical modeling of space and time)

Concepts of the origin of space and time:

1) Substantial(Democritus, Plato, Newton)

Space and time are considered as absolute, along with matter in the rank of substances. They exist independently, independently of material objects, and are regarded as pure extension and pure duration.

2) relational(Aristotle, Leibniz, and in our time Einstein, Lobachevsky)

Space and time are a special relationship between objects and do not exist independently and separately from them. Those. if for Newton the board occupies some position, then for Leibniz the space is the ratio of the board with the objects surrounding it.

Two philosophically important conclusions followed from the theory of relativity: firstly, at speeds close to the speed of light, the lengths of bodies are reduced by about half; secondly, the rate of flow of time processes slows down at a speed close to light, by about 40 times. The theory of relativity has shown the dependence of space (the length of bodies) and time (the rate of duration of processes) on the speed of moving bodies.

Matter- 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. observed in nature different kinds motion of matter: mechanical, oscillatory and wave, thermal motion of atoms and molecules, equilibrium and non-equilibrium processes, radioactive decay, chemical and nuclear reactions, 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 continual (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 microworld 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 - 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 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 signs 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 of the existence of such particles, called quarks, was put forward in 1964 by the American physicist M. Gell-Man ( Nobel Prize 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:

♦ photons (gr. photos- particles that have no rest mass and move at the speed of light);

♦ leptons (gr. leptos- light) - light particles (electron and neutrino);

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

♦ baryons (gr. 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:

♦ particles with a negative charge (for example, electrons);

♦ particles with a positive charge (eg proton, positrons);

♦ particles with zero charge (for example, neutrinos).

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

♦ hadrons (gr. adros- large, strong), participating in electromagnetic, strong and weak interaction;

♦ leptons participating only in electromagnetic and weak interactions;

♦ particles - carriers of interactions (photons - carriers of electromagnetic interaction; gravitons - carriers of gravitational interaction; gluons - carriers of strong interaction; intermediate vector bosons - carriers of 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.

2.2. Fundamental Interactions

Interaction is the main reason for the movement of matter, therefore interaction is inherent in all material objects, regardless of their natural origin and systemic organization. Features of various interactions determine the conditions of existence and the specifics of the properties of material objects. In total, four types of interaction are known: gravitational, electromagnetic, strong and weak.

gravitational interaction was the first of the known fundamental interactions to become the subject of research by scientists. It manifests itself in the mutual attraction of any material objects that have mass, is transmitted through the gravitational field and is determined by the law of universal gravitation, which was formulated by I. Newton

The law of universal gravitation describes the fall of material bodies in the field of the Earth, the movement of the planets of the solar system, stars, etc. As the mass of matter increases, gravitational interactions increase. Gravitational interaction is the weakest of all known modern science interactions. Nevertheless, gravitational interactions determine the structure of the entire Universe: the formation of all cosmic systems; existence of planets, stars and galaxies. The important role of gravitational interaction is determined by its universality: all bodies, particles and fields participate in it.

The carriers of gravitational interaction are gravitons - gravitational field quanta.

electromagnetic the interaction is also universal and exists between any bodies in the micro, macro and mega worlds. Electromagnetic interaction is due to electric charges and is transmitted using electric and magnetic fields. An electric field arises in the presence of electric charges, and a magnetic field arises when electric charges move. Electromagnetic interaction is described by: Coulomb's law, Ampère's law, etc. and in a generalized form - Maxwell's electromagnetic theory, which relates electric and magnetic fields. Due to the electromagnetic interaction, atoms, molecules arise and chemical reactions occur. Chemical reactions are a manifestation of electromagnetic interactions and are the results of the redistribution of bonds between atoms in molecules, as well as the number and composition of atoms in the molecules of different substances. Various aggregate states of matter, elastic forces, friction, etc. are determined by electromagnetic interaction. The carriers of the electromagnetic interaction are photons - quanta of the electromagnetic field with zero rest mass.

Inside the atomic nucleus, strong and weak interactions are manifested. strong interaction ensures the connection of nucleons in the nucleus. This interaction is determined by nuclear forces, which have charge independence, short range, saturation, and other properties. The strong force keeps nucleons (protons and neutrons) in the nucleus and quarks inside nucleons and is responsible for the stability of atomic nuclei. Using the strong force, scientists have explained why the protons of the nucleus of an atom do not fly apart under the influence of electromagnetic repulsive forces. The strong force is transmitted by gluons, particles that “stick together” quarks, which are part of protons, neutrons, and other particles.

Weak interaction also operates only in the microcosm. All elementary particles, except for the photon, participate in this interaction. It causes most of the decays of elementary particles, so its discovery occurred after the discovery of radioactivity. The first theory of the weak interaction was created in 1934 by E. Fermi and developed in the 1950s. M. Gell-Man, R. Feynman and other scientists. The carriers of weak interaction are considered to be particles with a mass 100 times greater than the mass of protons - intermediate vector bosons.

Characteristics of fundamental interactions are presented in Table. 2.1.

Table 2.1

Characteristics of fundamental interactions

The table shows that the gravitational interaction is much weaker than other interactions. Its range is unlimited. It does not play a significant role in microprocesses and at the same time is the main one for objects with large masses. The electromagnetic interaction is stronger than the gravitational one, although the radius of its action is also unlimited. The strong and weak interactions have a very limited range.

One of the most important tasks of modern natural science is the creation of a unified theory of fundamental interactions that unites various types of interaction. The creation of such a theory would also mean the construction of a unified theory of elementary particles.

2.3. Thermal radiation. The birth of quantum concepts

At the end of the XX century. wave theory could not explain and describe thermal radiation in the entire frequency range of electromagnetic waves in the thermal range. And the fact that thermal radiation, and in particular light, are electromagnetic waves, has become scientific fact. The German physicist Max Planck managed to give an accurate description of thermal radiation.

On December 14, 1900, Planck made a report at a meeting of the German Physical Society, in which he outlined his hypothesis of the quantum nature of thermal radiation and a new formula for radiation (Planck's formula). Physicists consider this day the birthday of a new physics - quantum. The outstanding French mathematician and physicist A. Poincaré wrote: "Planck's quantum theory is, without any doubt, the biggest and most profound revolution that natural philosophy has undergone since the time of Newton."

Planck established that thermal radiation (an electromagnetic wave) is emitted not in a continuous stream, but in portions (quanta). The energy of each quantum is

that is, proportional to the frequency of the electromagnetic wave - v. Here h- Planck's constant, equal to 6.62 10 -34 J s.

The agreement between Planck's calculations and experimental data was complete. In 1919, M. Planck was awarded the Nobel Prize.

Based on quantum concepts, A. Einstein in 1905 developed the theory of the photoelectric effect (Nobel Prize in 1922), putting science before the fact: light has both wave and corpuscular properties, it is emitted, propagated and absorbed by quanta (portions). Light quanta were called photons.

2.4. De Broglie's hypothesis about wave-particle duality of particle properties

The French scientist Louis de Broglie (1892-1987) in 1924 in his doctoral dissertation "Studies in the theory of quantum" put forward a bold hypothesis about the universality of wave-particle duality, arguing that since light behaves like a wave in some cases, and in others - as a particle, then material particles (electrons, etc.) due to the general nature of the laws of nature must have wave properties. “In optics,” he wrote, “for a century, the corpuscular method of consideration was too neglected in comparison with the wave method; Was the reverse error made in the theory of matter? Haven't we thought too much about the picture of "particles" and neglected the excessive picture of waves? At the time, de Broglie's hypothesis looked crazy. Only in 1927, three years later, science experienced a huge shock: the physicists K. Davisson and L. Germer experimentally confirmed de Broglie's hypothesis, having obtained a diffraction pattern of electrons.

According to the quantum theory of light by A. Einstein, the wave characteristics of photons of light (oscillation frequency v and wavelength l \u003d c / v) are associated with corpuscular characteristics (energy ε f, relativistic mass m f and momentum p f) by the relations:

According to de Broglie's idea, any microparticle, including those with a rest mass w 0 C 0, must have not only corpuscular, but also wave properties. Corresponding frequency v and the wavelength l are determined in this case by relations similar to those of Einstein:

Hence the de Broglie wavelength -

Thus, Einstein's relations, obtained by him in the construction of the theory of photons as a result of the hypothesis put forward by de Broglie, acquired a universal character and became equally applicable both to the analysis of the corpuscular properties of light and to the study of the wave properties of all microparticles.

2.5. Rutherford's experiments. Rutherford model of the atom

A. Rutherford's experiments

In 1911, Rutherford conducted experiments of exceptional significance that proved the existence of the atomic nucleus. To study the atom, Rutherford used its probing (bombardment) with the help of α-particles, which arise during the decay of radium, polonium and some other elements. Rutherford and his collaborators, even in earlier experiments in 1909, found that α-particles have a positive charge equal in modulus to twice the electron charge q =+2e, and a mass coinciding with the mass of a helium atom, i.e.

m a\u003d 6.62 10 -27 kg,

which is about 7300 times the mass of an electron. Later it was found that α-particles are the nuclei of helium atoms. With these particles, Rutherford bombarded the atoms of heavy elements. Electrons due to their small mass cannot change the trajectory of the α-particle. Their scattering (changing the direction of movement) can only be caused by the positively charged part of the atom. Thus, from the scattering of α-particles, one can determine the nature of the distribution of the positive charge, and hence the mass inside the atom.

It was known that α-particles emitted by polonium fly at a speed of 1.6-107 m/s. The polonium was placed inside a lead case, along which a narrow channel was drilled. The α-particle beam, having passed through the channel and the aperture, was incident on the foil. Gold foil can be made extremely thin - 4-10 -7 m thick (400 gold atoms; this number can be estimated by knowing the mass, density and molar mass of gold). After the foil, the α-particles hit a semitransparent screen coated with zinc sulfide. The collision of each particle with the screen was accompanied by a flash of light (scintillation) due to fluorescence, which was observed under a microscope.

With a good vacuum inside the device (so that there was no scattering of particles from air molecules), in the absence of foil, a bright circle appeared on the screen from scintillations caused by a thin beam of α-particles. When a foil was placed in the path of the beam, the vast majority of α-particles still did not deviate from their original direction, that is, they passed through the foil as if it were empty space. However, there were alpha particles that changed their path and even bounced back.

Marsden and Geiger, Rutherford's students and collaborators, counted more than a million scintillations and determined that about one in 2,000 α-particles deflected through angles greater than 90°, and one in 8,000 through 180°. It was impossible to explain this result on the basis of other models of the atom, in particular Thomson.

Calculations show that when distributed throughout the atom, a positive charge (even without taking into account electrons) cannot create a sufficiently intense electric field capable of throwing an α-particle back. The electric field strength of a uniformly charged ball is maximum on the surface of the ball and decreases to zero as it approaches the center. Scattering of α-particles at large angles occurs as if the entire positive charge of the atom was concentrated in its nucleus - a region that occupies a very small volume compared to the entire volume of the atom.

The probability of α-particles hitting the nucleus and deflecting them through large angles is very small, so for the majority of α-particles the foil did not seem to exist.

Rutherford theoretically considered the problem of the scattering of α-particles in the Coulomb electric field of a nucleus and obtained a formula that makes it possible to determine the number N elementary positive charges +e contained in the nucleus of atoms of a given scattering foil. Experiments have shown that the number N equal to the ordinal number of the element in the periodic system of D. I. Mendeleev, that is N=Z(for gold Z= 79).

Thus, Rutherford's hypothesis about the concentration of a positive charge in the nucleus of an atom made it possible to establish the physical meaning of the ordinal number of an element in the periodic system of elements. The neutral atom must also contain Z electrons. It is essential that the number of electrons in an atom, determined by various methods, coincided with the number of elementary positive charges in the nucleus. This served as a test of the validity of the nuclear model of the atom.

B. Rutherford's nuclear model of the atom

Summarizing the results of experiments on the scattering of α-particles by gold foil, Rutherford established:

♦ atoms by their nature are largely transparent to α-particles;

♦ deviations of α-particles at large angles are possible only if there is a very strong electric field inside the atom, created by a positive charge associated with a large mass concentrated in a very small volume.

To explain these experiments, Rutherford proposed a nuclear model of the atom: in the atomic nucleus (regions with linear dimensions of 10 -15 -10 -14 m) all of its positive charge and almost the entire mass of the atom (99.9%) are concentrated. Around the nucleus in a region with linear dimensions of ~10 -10 m (the dimensions of the atom are estimated in the molecular-kinetic theory), negatively charged electrons move in closed orbits, the mass of which is only 0.1% of the mass of the nucleus. Consequently, the electrons are located at a distance from the nucleus from 10,000 to 100,000 diameters of the nucleus, that is, the main part of the atom is empty space.

Rutherford's nuclear model of atoms resembles the solar system: in the center of the system is the "sun" - the nucleus, and "planets" - electrons - orbit around it, therefore this model is called planetary. The electrons do not fall on the nucleus because the electrical forces of attraction between the nucleus and the electrons are balanced by the centrifugal forces due to the rotation of the electrons around the nucleus.

In 1914, three years after the creation of the planetary model of the atom, Rutherford investigated the positive charges in the nucleus. By bombarding hydrogen atoms with electrons, he found that neutral atoms turned into positively charged particles. Since the hydrogen atom has one electron, Rutherford decided that the nucleus of an atom is a particle carrying an elementary positive charge +e. He called this particle proton.

The planetary model is in good agreement with experiments on the scattering of α-particles, but it cannot explain the stability of the atom. Consider, for example, a model of a hydrogen atom containing a proton nucleus and one electron that moves at a speed v around the nucleus in a circular orbit of radius r. The electron must spiral into the nucleus, and the frequency of its revolution around the nucleus (hence, the frequency of electromagnetic waves emitted by it) must continuously change, that is, the atom is unstable, and its electromagnetic radiation must have a continuous spectrum.

In fact, it turns out that:

a) the atom is stable;

b) an atom radiates energy only under certain conditions;

c) the radiation of an atom has a line spectrum determined by its structure.

Thus, the application of classical electrodynamics to the planetary model of the atom led to a complete contradiction with the experimental facts. Overcoming the difficulties that arose required the creation of a qualitatively new quantum- Theories of the atom. However, despite its inconsistency, the planetary model is still accepted as an approximate and simplified picture of the atom.

2.6. Bohr's theory for the hydrogen atom. Bohr's postulates

The Danish physicist Niels Bohr (1885-1962) in 1913 created the first quantum theory of the atom, linking into a single whole the empirical regularities of the line spectra of hydrogen, Rutherford's nuclear model of the atom, and the quantum nature of the emission and absorption of light.

Bohr based his theory on three postulates, about which the American physicist L. Cooper remarked: “Of course, it was somewhat presumptuous to put forward proposals that contradicted Maxwell’s electrodynamics and Newton’s mechanics, but Bohr was young.”

First postulate(postulate of stationary states): in an atom, electrons can move only along certain, so-called allowed, or stationary, circular orbits, in which, despite their acceleration, they do not radiate electromagnetic waves (therefore, these orbits are called stationary). An electron in each stationary orbit has a certain energy E n .

Second postulate(frequency rule): an atom emits or absorbs a quantum of electromagnetic energy when an electron moves from one stationary orbit to another:

hv \u003d E 1 - E 2,

where E 1 and E 2 are the electron energy before and after the transition, respectively.

When E 1 > E 2, a quantum is emitted (the transition of an atom from one state with a higher energy to a state with a lower energy, that is, the transition of an electron from any farthest to any orbit closest to the nucleus); at E 1< E 2 - поглощение кванта (переход атома в состояние с большей энергией, то есть переход электрона на более удаленную от ядра орбиту).

Convinced that Planck's constant must play a fundamental role in the theory of the atom, Bohr introduced third postulate(quantization rule): in stationary orbits the angular momentum of the electron L n = m e u n r n is a multiple of = h/(2π), i.e.

m e υ n r n = nh, n = 1, 2, 3, …,

where \u003d 1.05 10 -34 J s - Planck's constant (the value h / (2π)) occurs so often that a special designation has been introduced for it (“ash” with a line; in this work, “ash” is direct); m e = 9.1 10 -31 kg - electron mass; r P- radius n-th stationary orbits; υ n is the speed of the electron in this orbit.

2.7. Hydrogen atom in quantum mechanics

The equation of motion of a microparticle in various force fields is the wave Schrödinger equation.

For stationary states, the Schrödinger equation will be:

where Δ is the Laplace operator

, m is the mass of the particle, h is Planck's constant, E- total energy, U- potential energy.

The Schrödinger equation is a second-order differential equation and has a solution that indicates that the total energy in the hydrogen atom must be discrete:

E 1 , E 2 , E 3…

This energy is at the appropriate levels n\u003d 1,2,3, ... according to the formula:

The lowest level E corresponds to the minimum possible energy. This level is called the main level, all the rest are excited.

As the principal quantum number increases n the energy levels are closer together, the total energy decreases, and when n= ∞ it is equal to zero. At E>0 the electron becomes free, unbound to a specific nucleus, and the atom becomes ionized.

A complete description of the state of an electron in an atom, in addition to energy, is associated with four characteristics, which are called quantum numbers. These include: the principal quantum number P, orbital quantum number l, magnetic quantum number m 1 , magnetic spin quantum number m s .

The wave φ-function, which describes the motion of an electron in an atom, is not a one-dimensional, but a spatial wave, corresponding to three degrees of freedom of an electron in space, that is, the wave function in space is characterized by three systems. Each of them has its own quantum numbers: n, l, m l .

Each microparticle, including an electron, also has its own internal complex motion. This movement can be characterized by the fourth quantum number m s . Let's talk about this in more detail.

A. The main quantum number n, according to the formula, determines the energy levels of an electron in an atom and can take on the values P= 1, 2, 3…

B. Orbital quantum number /. It follows from the solution of the Schrödinger equation that the angular momentum of an electron (its mechanical orbital momentum) is quantized, that is, it takes on discrete values ​​determined by the formula

where L l is the angular momentum of an electron in orbit, l- orbital quantum number, which for a given P takes on the value i= 0, 1, 2… (n- 1) and determines the angular momentum of an electron in an atom.

b. Magnetic quantum number m l. It also follows from the solution of the Schrödinger equation that the vector l l(momentum of an electron) is oriented in space under the influence of an external magnetic field. In this case, the vector will unfold in such a way that its projection onto the direction of the external magnetic field will be

Llz= hm l

where m l called magnetic quantum number, which can take the values m l= 0, ±1, ±2, ±1, that is, there are (2l + 1) values ​​in total.

Given the above, we can conclude that a hydrogen atom can have the same energy value, being in several different states (n is the same, and l and m l- different).

When an electron moves in an atom, the electron noticeably exhibits wave properties. Therefore, quantum electronics generally refuses classical ideas about electron orbits. We are talking about determining the probable location of the electron in orbit, that is, the location of the electron can be represented by a conditional "cloud". The electron during its movement is as if "smeared" over the entire volume of this "cloud". quantum numbers n and l characterize the size and shape of the electron "cloud", and the quantum number m l- the orientation of this "cloud" in space.

In 1925 American physicists Uhlenbeck and Goudsmit proved that the electron also has its own angular momentum (spin), although we do not consider the electron to be a complex microparticle. Later it turned out that protons, neutrons, photons and other elementary particles have spin.

Experiences Stern, Gerlach and other physicists led to the need to characterize the electron (and microparticles in general) by an additional internal degree of freedom. Hence, for a complete description of the state of an electron in an atom, it is necessary to set four quantum numbers: the main thing is P, orbital - l, magnetic - m l, magnetic spin number - m s .

V quantum physics it has been established that the so-called symmetry or asymmetry of the wave functions is determined by the spin of the particle. Depending on the nature of the symmetry of the particles, all elementary particles and the atoms and molecules built from them are divided into two classes. Particles with half-integer spin (for example, electrons, protons, neutrons) are described by asymmetric wave functions and obey Fermi-Dirac statistics. These particles are called fermions. Particles with integer spin, including zero, such as photon (Ls=1) or n-meson (Ls= 0) are described by symmetric wave functions and obey Bose-Einstein statistics. These particles are called bosons. Complex particles (for example, atomic nuclei), composed of an odd number of fermions, are also fermions (the total spin is half-integer), and those composed of an even number are bosons (the total spin is integer).

2.8. Multi-electron atom. Pauli principle

In a multi-electron atom whose charge is Ze, the electrons will occupy different "orbits" (shells). When moving around the nucleus, Z-electrons are arranged in accordance with a quantum mechanical law, which is called Pauli principle(1925). It is formulated like this:

> 1. In any atom, there cannot be two identical electrons determined by a set of four quantum numbers: the main n, orbital / magnetic m and magnetic spin m s .

> 2. In states with a certain value, no more than 2n 2 electrons can be in an atom.

This means that only 2 electrons can be on the first shell (“orbit”), 8 on the second, 18 on the third, etc.

Thus, the set of electrons in a multi-electron atom that have the same principal quantum number n is called electronic shell. In each of the shells, the electrons are arranged in subshells that correspond to a certain value of /. Since the orbital quantum number l takes values ​​from 0 to (n - 1), the number of subshells is equal to the ordinal number of the shell P. The number of electrons in a subshell is determined by the magnetic quantum number m l and magnetic spin number m s .

The Pauli principle has played an outstanding role in the development of modern physics. So, for example, it was possible to theoretically substantiate the periodic system of elements of Mendeleev. Without the Pauli principle, it would be impossible to create quantum statistics and the modern theory of solids.

2.9. Quantum-mechanical substantiation of the Periodic law of D. I. Mendeleev

In 1869, D. I. Mendeleev discovered the periodic law of change in chemical and physical properties elements depending on their atomic masses. D. I. Mendeleev introduced the concept of the serial number of the Z-element and, arranging the chemical elements in ascending order of their number, obtained a complete periodicity in the change in the chemical properties of the elements. The physical meaning of the serial number of the Z-element in the periodic system was established in Rutherford's nuclear model of the atom: Z coincides with the number of positive elementary charges in the nucleus (protons) and, accordingly, with the number of electrons in the shells of atoms.

The Pauli principle gives an explanation of the Periodic system of D. I. Mendeleev. Let's start with the hydrogen atom, which has one electron and one proton. Each subsequent atom will be obtained by increasing the charge of the nucleus of the previous atom by one (one proton) and adding one electron, which we will place in a state accessible to it, according to the Pauli principle.

At the hydrogen atom Z= 1 on the shell 1 electron. This electron is located on the first shell (K-shell) and has a state of 1S, that is, it has n=1,a l=0(S-state), m= 0, m s = ±l/2 (the orientation of its spin is arbitrary).

A helium (He) atom has Z = 2, there are 2 electrons on the shell, both of them are located on the first shell and have a state 1S, but with antiparallel orientation of the spins. On the helium atom, the filling of the first shell (K-shell) ends, which corresponds to the completion of the first period of the Periodic Table of Elements of D. I. Mendeleev. According to the Pauli principle, more than 2 electrons cannot be placed on the first shell.

At the lithium atom (Li) Z\u003d 3, there are 3 electron shells: 2 - on the first shell (K-shell) and 1 - on the second (L-shell). In the first shell, the electrons are in the state 1S, and on the second - 2S. Lithium begins the II period of the table.

At the beryllium atom (Be) Z= 4, on the shells 4 electrons: 2 on the first shell in the state IS and 2 on the second in the 2S state.

The next six elements - from B (Z = 5) to Ne (Z = 10) - are filling the second shell, while the electrons are both in the 2S state and in the 2p state (the second shell has 2 sub-shells).

At the sodium atom (Na) Z= 11. Its first and second shells, according to the Pauli principle, are completely filled (2 electrons on the first and 8 electrons on the second shells). Therefore, the eleventh electron is located on the third shell (M-shell), occupying the lowest state 3 S. Sodium opens the III period of the Periodic system of D. I. Mendeleev. Arguing in this way, you can build the entire table.

Thus, the periodicity in the chemical properties of elements is explained by the repeatability in the structure of the outer shells of atoms of related elements. So, inert gases have identical outer shells of 8 electrons.

2.10. Basic concepts of nuclear physics

The nuclei of all atoms can be divided into two large classes: stable and radioactive. The latter spontaneously decay, turning into nuclei of other elements. Nuclear transformations can also occur with stable nuclei when they interact with each other and with various microparticles.

Any nucleus is positively charged, and the magnitude of the charge is determined by the number of protons in the nucleus Z (charge number). The number of protons and neutrons in the nucleus determines the mass number of the nucleus A. Symbolically, the nucleus is written as follows:

where X- symbol of a chemical element. Nuclei with the same charge number Z and different mass numbers A are called isotopes. For example, uranium occurs in nature mainly in the form of two isotopes

Isotopes have the same chemical properties and different physical For example, an isotope of uranium 2 3 5 92 U interact well with the neutron 1 0 n of any energy and can split into two lighter nuclei. At the same time, the uranium isotope 23892U is divided only when interacting with high-energy neutrons, more than 1 megaelectronvolt (MeV) (1 MeV = 1.6 10 -13 J). nuclei with the same A and different Z called isobars.

While the charge of the nucleus is equal to the sum of the charges of the protons entering it, the mass of the nucleus is not equal to the sum of the masses of individual free protons and neutrons (nucleons), it is somewhat less than it. This is explained by the fact that for the binding of nucleons in the nucleus (for the organization of strong interaction) the binding energy is required E. Each nucleon (both proton and neutron), getting into the nucleus, figuratively speaking, allocates a part of its mass for the formation of an intranuclear strong interaction, which "glues" the nucleons in the nucleus. At the same time, according to the theory of relativity (see Chapter 3), between the energy E and weight m there is a relation E = mc 2 , where With is the speed of light in vacuum. So the formation of the binding energy of nucleons in the nucleus E St. leads to a decrease in the mass of the nucleus by the so-called mass defect Δm = E St. c 2 . These ideas are confirmed by numerous experiments. Having plotted the dependence of the binding energy per nucleon Esv / A= ε on the number of nucleons in the nucleus A, we will immediately see the non-linear nature of this dependence. Specific binding energy ε with increasing A first increases steeply (for light nuclei), then the characteristic approaches the horizontal (for medium nuclei), and then slowly decreases (for heavy nuclei). Uranium has ε ≈ 7.5 MeV, while medium nuclei have ε ≈ 8.5 MeV. Medium nuclei are the most stable, they have a large binding energy. This opens up the possibility of obtaining energy by dividing a heavy nucleus into two lighter (medium) ones. Such a nuclear fission reaction can be carried out by bombarding a uranium nucleus with a free neutron. For instance, 2 3 5 92 U is divided into two new nuclei: rubidium 37 -94 Rb and cesium 140 55 Cs (one of the variants of uranium fission). The fission reaction of a heavy nucleus is remarkable in that, in addition to new lighter nuclei, two new free neutrons appear, which are called secondary. In this case, each fission event accounts for 200 MeV of the released energy. It is released in the form of the kinetic energy of all fission products and can then be used, for example, to heat water or another coolant. Secondary neutrons, in turn, can cause fission of other uranium nuclei. A chain reaction is formed, as a result of which huge energy can be released in the breeding medium. This method of generating energy is widely used in nuclear weapons and controlled nuclear power plants in power plants and transport facilities with nuclear power.

In addition to the indicated method of obtaining atomic (nuclear) energy, there is another one - the fusion of two light nuclei into a heavier nucleus. The process of unification of light nuclei can occur only when the initial nuclei approach each other at a distance where nuclear forces already act (strong interaction), that is, ~ 10 - 15 m. This can be achieved at ultrahigh temperatures of the order of 1,000,000 °C. Such processes are called thermonuclear reactions.

Thermonuclear reactions in nature take place in stars and, of course, in the Sun. Under the conditions of the Earth, they occur during the explosions of hydrogen bombs (thermonuclear weapons), the fuse for which is a conventional atomic bomb, which creates conditions for the formation of ultrahigh temperatures. Controlled thermonuclear fusion has so far only a research focus. There are no industrial installations, but work in this direction is being carried out in all developed countries, including Russia.

2.11. Radioactivity

Radioactivity is the spontaneous transformation of one nucleus into another.

Spontaneous decay of isotopes of nuclei in the natural environment is called natural, and in laboratory conditions as a result of human activity - artificial radioactivity.

Natural radioactivity was discovered by the French physicist Henri Becquerel in 1896. This discovery caused a revolution in natural science in general and in physics in particular. Classical physics of the XIX century. with its conviction in the indivisibility of the atom, it has become a thing of the past, giving way to new theories.

The discovery and study of the phenomenon of radioactivity is also associated with the names of Marie and Pierre Curie. These researchers were awarded the Nobel Prize in Physics in 1903.

Artificial radioactivity was discovered and studied by the spouses Irene and Frederic Joliot-Curie, who also received the Nobel Prize in 1935.

It should be noted that there is no fundamental difference between these two types of radioactivity.

Quantitative estimates have been established for each radioactive element. Thus, the probability of the decay of one atom in one second is characterized by the decay constant of the given element l, and the time for which half of the radioactive sample decays is called the half-life Г 05.

Over time, the number of undecayed nuclei N decreases exponentially:

N= N 0 e -λt ,

where N 0 is the number of undecayed nuclei at a time t = t 0 (that is, the initial number of atoms), N- the current value of the number of undecayed

This law is called the elementary law of radioactive decay. From it you can get the formula for the half-life:

The number of radioactive decays in a sample in one second is called the activity of the radioactive drug. Most often, activity is denoted by the letter A then by definition:

where the sign "-" means decreasing N in time.

The unit of activity in the SI system is Becquerel (Bq): 1 Bq = 1 decay / 1 s. Often in practice, an off-system unit is used - Curie (Ci), 1 Ci \u003d 3.7 10 10 Bq.

It can be shown that activity decreases with time also according to an exponential law:

A=A 0 e -λt .

Questions for self-examination

1. What is matter? What types of matter are distinguished in the modern view?

2. Explain the concept of "elementary particles". Name the most important characteristics of elementary particles. How are elementary particles classified?

3. How many types of interaction do you know? List their main features.

4. What are antiparticles?

5. What is the specificity of the study of the microcosm in comparison with the study of the mega- and macrocosms?

6. Describe briefly the history of the development of ideas about the structure of the atom.

7. Formulate N. Bohr's postulates. Is it possible to explain the structure of atoms of all elements of the table of D. I. Mendeleev using the theory of N. Bohr?

8. Who and when created the theory of the electromagnetic field?

9. What is radioactivity?

10. Name the main types of radioactive decay.

- 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 microworld 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 attributes 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.

What types of matter exist? and got the best answer

Answer from Ell04ka[guru]
two things are studied at school: matter and field.
But in general...
1 Substance
- Hadron matter - the bulk of this type of matter is made up of elementary particles hadrons
+ Baryon matter (baryon matter) - the main (by mass) component - baryons
# Substance in the classical sense. Consists of atoms in the usual sense of the word, that is, of atoms containing protons, neutrons and electrons. This form of matter dominates the solar system and nearby star systems.
# Antimatter - consists of antiatoms containing antiprotons, antineutrons and positrons
# Neutron substance - consists mainly of neutrons and is devoid of atomic structure. The main component of neutron stars, significantly denser than ordinary matter, but less dense than quark-gluon plasma
- Other types of substances having an atom-like structure (for example, a substance formed by mesoatoms with muons)
- Quark-gluon plasma - a superdense form of matter that existed on early stage the evolution of the Universe before the unification of quarks into classical elementary particles (before confinement)
- Pre-quark superdense material formations, the components of which are strings and other objects with which grand unified theories operate (see string theory, superstring theory). The main forms of matter that supposedly existed at an early stage in the evolution of the universe. String-like objects in modern physical theory claim to be the most fundamental material formations, to which all elementary particles, i.e., ultimately, all known forms of matter, can be reduced. This level of matter analysis, perhaps, will allow explaining the properties of various elementary particles from a unified standpoint. Belonging to "substance" here should be understood conditionally, since the difference between the material and field forms of matter at this level is erased

2 Field (in the classical sense)
- Electromagnetic field
- Gravity field
3 Quantum fields of different nature. According to modern ideas the quantum field is a universal form of matter, to which both substances and classical fields can be reduced
4 Material objects of obscure physical nature
- Dark matter
- Dark energy
Source: Wikipedia - Article on matter (physics)

Answer from 2 answers[guru]

Hey! Here is a selection of topics with answers to your question: What types of matter exist?

Answer from Artyom Perevedentsev[newbie]
Basic types of matter [edit | edit wiki text]
Main article: Forms of matter
Substance:
Hadron matter - its structure is a set of compound particles: hadrons.
Baryon matter (baryon matter) - a substance consisting of baryons.
Substance in the classical sense. It consists mainly of fermions. This form of matter dominates the solar system and nearby star systems.
Antimatter is made up of antiparticles.
Neutron matter - consists mainly of neutrons and is devoid of atomic structure. The main component of neutron stars, much denser than ordinary matter, but less dense than quark-gluon plasma.
Other types of substances having an atom-like structure (for example, a substance formed by mesoatoms with muons).
Quark-gluon plasma is a superdense form of matter that existed at an early stage of the evolution of the Universe before the unification of quarks into classical elementary particles (before confinement).
Hypothetical pre-quark superdense material formations, the components of which are strings and other objects with which grand unified theories operate (see string theory, superstring theory). The main forms of matter that supposedly existed at an early stage in the evolution of the universe. String-like objects in modern physical theory claim to be the most fundamental material formations, to which all elementary particles, that is, ultimately, all known forms of matter, can be reduced. This level of matter analysis, perhaps, will allow explaining the properties of various elementary particles from a unified standpoint. Belonging to the "substance" here should be understood conditionally, since the difference between the material and field forms of matter at this level is erased.
The field, unlike matter, has no internal voids, it has an absolute density.
Field (in the classical sense):
Electromagnetic field.
gravitational field.
Quantum fields of different nature. According to modern concepts, the quantum field is a universal form of matter, to which both substances and classical fields can be reduced, while there is a fuzzy division into real fields (lepton and quark fields of fermionic nature) and interaction fields (gluon strong, intermediate bosonic weak and photon electromagnetic field of bosonic nature, this also includes the hypothetical field of gravitons). Standing apart among them is the Higgs field, which is difficult to attribute unambiguously to any of these categories.
Material objects of obscure physical nature:
Dark matter.
Dark energy.
These objects were introduced into scientific use to explain a number of astrophysical and cosmological phenomena.

Answer from Ilgiz Karimov[newbie]
Thank you very much I like it))

Answer from Max games[newbie]
Matter is the content of our being. It is an objective reality, fills space and serves as the main component of all living and non-living elements. Two seemingly incompatible areas of knowledge, such as science and philosophy, agree on only one thing - that matter plays a dominant role in the life of micro- and macroworlds. What is the matter that surrounds us and from which we are made? Why does it take such strange forms, many of which are not even revealed to us yet? Let's try to understand this a little.
How did the great people understand this term?
About what matter consists of, and how it changes its forms so dramatically, people began to think since antiquity. In those years there were no microscopes and telescopes, and even the wisest philosophers could not study any human organ or just a piece of wood from which a chair was knocked down to the atomic level. However, ancient experts clearly knew what space-time is and how all elements behave in it. It was they who made the interpretation that has come down to our days. Matter was divided into two halves: things filled space, and events filled time. Due to the constant course of the latter, all objects and living objects could change their shape. A person was born, grew old and died, wood crumbled, metal rusted. In the 17th century, the physicist and mathematician Leibniz defined matter as a subject that determines the properties of time and space. Later, his works appeared in Einstein's theory of relativity. what is matter made of
Looking at something under a microscope
If we turn to biological optics for help, we can see with our own eyes that matter consists of atoms. This is the simplest characteristic of this term, which has no refutation and does not require further proof. Atoms are the smallest particles of everything that surrounds us, and ourselves. The structure of each of them is identical. But at the same time, in the atoms of each individual element of our world, whether it be a methane cloud in the atmosphere of Jupiter or a dog's liver, information about the properties of the carrier object is encoded. An atom consists of a nucleus, which is always positively charged, and electrons. When the number of protons and electrons matches, the given particle becomes neutral in terms of electric charge. If the equilibrium is disturbed, then the atom turns into an ion, which has a positive or negative charge. matter is made up of atoms
What are the atoms poured into?
A molecule is formed from the accumulation of two or more atoms. In addition to information about the carrier, it also contains a considerable proportion of the connecting substance. Thanks to him, molecules are able to form the very matter that we are talking about. Such compounds transmit information from different atoms through each other and thus create an inseparable substance. The most interesting thing is that molecules of initially different components can be grouped. The most striking example here is water: it contains hydrogen and oxygen in a certain percentage. It turns out that in order to understand what matter consists of, we only need to study the elements of the periodic table of Mendeleev and find them in various objects that surround us. matter is made up of matter
What do we see with the naked eye?
Pushing the telescope aside, we, having received certain knowledge, see that matter consists of matter. Due to its structure, which can be seen through optics, it is able to take one of four states of aggregation: gaseous, liquid, solid and plasma. We can easily represent the first three of them using the example of the same water, which, being liquid, can turn into ice or into gas. Some other elements can only exist in one of these four states. Delving into ancient philosophy, it is impossible not to draw an analogy with the four elements.