Quarks: It is now known that hadrons consist of quarks and antiquarks. To date, quarks and antiquarks are considered indivisible, there are 6 types of them, which are called "flavors". The most unusual property of quarks is that they exist only inside hadrons and are not observed as independently existing particles. they have a fractional electric and baryon charge. Baryons and mesons are made up of quarks.

Elementary particles can also be classified as follows:

1) By spin: into fermions (half-integer spin) and bosons (whole spin).

2) According to the lifetime of the particle, it can be divided into: 1) stable (electron, proton, photon, neutrino); 2) quasi—stable – decaying due to electromagnetic and weak interactions (neutron); 3) unstable- decaying due to strong interaction (π mesons).

3) By mass, all particles are divided into three classes:

baryons (heavy): proton, neutron, hyperons, part of resonances. Of these, the proton is stable. They are all fermions. Have a baryon charge of +1. They participate in all types of interactions.

Mesons (medium, intermediate): pi-mesons, ka-mesons, etc. Unstable. Are bosons (zero or integer spin). There is no baryon charge. They participate in all types of interactions. Baryons + mesons = hadrons.

leptons (light): muon, neutrino, electron. Muons are fermions, do not participate in strong interactions and have a lepton charge.

Outside of these classes is a photon: not a lepton and not a hadron. There is no lepton charge, it does not participate in strong interactions. Participates in electromagnetic interactions, its spin = 1, and rest mass = 0.

Under certain conditions, a particle has a "double", an antiparticle with the opposite sign. Antiparticles have the same masses, lifetime, spin, isospin as particles. When a particle and an antiparticle meet each other, they annihilate, i.e. they turn into other particles.

The main provisions of modern atomistics:

an atom is a complex material structure, it is the smallest particle of a chemical element;

each element has varieties of atoms (contained in natural objects or artificially synthesized);

atoms of one element can transform into atoms of another; these processes are carried out either spontaneously (natural radioactive transformations) or artificially (through various nuclear reactions).

The substance we encounter in everyday life consists of atoms. Atoms include an atomic nucleus consisting of protons and neutrons, as well as electrons "rotating" around the nucleus (quantum mechanics uses the concept of an "electron cloud"). Protons and neutrons belong to hadrons (which consist of quarks). It should be noted that in laboratory conditions it was possible to obtain "atoms" consisting of other elementary particles.

The atoms of each chemical element have the same number of protons in their composition, called the atomic number or charge of the nucleus. However, the number of neutrons can vary, so one chemical element can be represented by several isotopes. Currently, over 110 elements are known, the most massive of which are unstable.

Atoms can interact with each other to form chemicals. The interaction takes place at the level of their electronic shells. Chemicals are extremely diverse. Science has not yet solved the problem of accurately predicting the physical properties of chemicals.

Elementary particles. Atom models.

Elementary particle is a collective term referring to micro—objects on a subnuclear scale, which at the moment in practice cannot be split into component parts.

However, some elementary particles (electron, neutrino, quarks, etc.) are currently considered structureless and are considered as primary fundamental particles. Other elementary particles (the so—called composite particles, including the particles that make up the nucleus of an atom – protons and neutrons) have a complex internal structure, but nevertheless, according to modern ideas, it is impossible to divide them into parts due to the confinement effect.

In total, more than 350 elementary particles have been discovered together with antiparticles. Of these, the photon, electron and muon neutrinos, electron, proton and their antiparticles are stable. The remaining elementary particles spontaneously decay exponentially with a time constant from about 880 seconds (for a free neutron) to an infinitesimal fraction of a second (from 10-24 to 10-22 seconds for resonances).

The structure and behavior of elementary particles is studied by elementary particle physics.

All elementary particles obey the principle of identity (all elementary particles of the same kind in the Universe are completely identical in all their properties) and the principle of particle-wave dualism (each elementary particle corresponds to a de Broglie wave).

All elementary particles have the property of interconvertibility, which is a consequence of their interactions: strong, electromagnetic, weak, gravitational. Interactions of particles cause transformations of particles and their aggregates into other particles and their aggregates, if such transformations are not prohibited by the laws of conservation of energy, momentum, angular momentum, electric charge, baryon charge, etc.

The main characteristics of elementary particles are: lifetime, mass, spin, electric charge, magnetic moment, baryon charge, lepton charge, strangeness, charm, charm, truth, isotopic spin, parity, charge parity, G-parity, CP-parity, T-parity, R-parity, P-parity.

All elementary particles are divided into two classes:

Stable elementary particles are particles that have an infinitely long lifetime in the free state (proton, electron, neutrino, photon, graviton and their antiparticles).

Unstable elementary particles are particles that decay into other particles in a free state in a finite time (all other particles).

All elementary particles are divided into two classes:

Massless particles are particles with zero mass (photon, gluon).

Particles with nonzero mass (all other particles).

All elementary particles are divided into two classes:

bosons are particles with whole spin (for example, photon, gluon, mesons, Higgs boson);

fermions are particles with half-integer spin (for example, electron, proton, neutron, neutrino).

Elementary particles are divided into the following groups:

Composite particles

Hadrons are particles involved in all kinds of fundamental interactions. They consist of quarks and are subdivided, in turn, into:

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