An atom is the smallest particle chemical element, preserving all its chemical properties. An atom consists of a nucleus, which has a positive electrical charge, and negatively charged electrons. The charge of the nucleus of any chemical element is equal to the product of Z and e, where Z is the serial number of this element in the periodic system of chemical elements, e is the value of the elementary electric charge.
Electron is the smallest particle of a substance with a negative electric charge e=1.6·10 -19 coulombs, taken as an elementary electric charge. Electrons, rotating around the nucleus, are located in the electron shells K, L, M, etc. K is the shell closest to the nucleus. The size of an atom is determined by the size of its electron shell. An atom can lose electrons and become a positive ion or gain electrons and become negative ion. The charge of an ion determines the number of electrons lost or gained. The process of turning a neutral atom into a charged ion is called ionization.
Atomic nucleus(the central part of the atom) consists of elementary nuclear particles - protons and neutrons. The radius of the nucleus is approximately one hundred thousand times smaller than the radius of the atom. Density atomic nucleus extremely large. Protons- these are stable elementary particles, having a unit positive electric charge and a mass 1836 times greater than the mass of an electron. A proton is the nucleus of an atom of the lightest element, hydrogen. The number of protons in the nucleus is Z. Neutron is a neutral (having no electric charge) elementary particle with a mass very close to the mass of a proton. Since the mass of the nucleus consists of the mass of protons and neutrons, the number of neutrons in the nucleus of an atom is equal to A - Z, where A is the mass number of a given isotope (see). The proton and neutron that make up the nucleus are called nucleons. In the nucleus, nucleons are connected by special nuclear forces.
The atomic nucleus contains a huge reserve of energy, which is released during nuclear reactions. Nuclear reactions occur when atomic nuclei interact with elementary particles or with the nuclei of other elements. As a result of nuclear reactions, new nuclei are formed. For example, a neutron can transform into a proton. In this case, a beta particle, i.e., an electron, is ejected from the nucleus.
The transition of a proton to a neutron in the nucleus can be carried out in two ways: either a particle with a mass equal to the mass of the electron, but with a positive charge, called a positron (positron decay), is emitted from the nucleus, or the nucleus captures one of the electrons from the K-shell closest to it (K -capture).
Sometimes the resulting nucleus has an excess of energy (is in an excited state) and, going into normal condition, releases excess energy in the form of electromagnetic radiation with a very short wavelength -. The energy released during nuclear reactions is practically used in various industries.
An atom (Greek atomos - indivisible) is the smallest particle of a chemical element that has its chemical properties. Every element is made up of atoms certain type. The atom consists of a nucleus, which carries a positive electric charge, and negatively charged electrons (see), forming its electron shells. The magnitude of the electric charge of the nucleus is equal to Z-e, where e is the elementary electric charge equal in magnitude to the charge of the electron (4.8·10 -10 electric units), and Z is the atomic number of this element in the periodic table of chemical elements (see .). Since a non-ionized atom is neutral, the number of electrons included in it is also equal to Z. The composition of the nucleus (see Atomic nucleus) includes nucleons, elementary particles with a mass approximately 1840 times greater than the mass of the electron (equal to 9.1 10 - 28 g), protons (see), positively charged, and neutrons having no charge (see). The number of nucleons in the nucleus is called the mass number and is designated by the letter A. The number of protons in the nucleus, equal to Z, determines the number of electrons entering the atom, the structure of the electron shells and the chemical properties of the atom. The number of neutrons in the nucleus is A-Z. Isotopes are varieties of the same element, the atoms of which differ from each other in mass number A, but have the same Z. Thus, in the nuclei of atoms of different isotopes of the same element there is different number neutrons with the same number of protons. When denoting isotopes, the mass number A is written above the element symbol, and the atomic number below; for example, isotopes of oxygen are designated: 
The dimensions of an atom are determined by the dimensions of the electron shells and are for all Z a value of the order of 10 -8 cm. Since the mass of all electrons of an atom is several thousand times less than the mass of the nucleus, the mass of the atom is proportional to the mass number. The relative mass of an atom of a given isotope is determined in relation to the mass of an atom of the carbon isotope C12, taken as 12 units, and is called the isotope mass. It turns out to be close to the mass number of the corresponding isotope. The relative weight of an atom of a chemical element is the average (taking into account the relative abundance of isotopes of a given element) value of the isotopic weight and is called atomic weight (mass).
The atom is a microscopic system, and its structure and properties can only be explained using quantum theory, created mainly in the 20s of the 20th century and intended to describe phenomena on the atomic scale. Experiments have shown that microparticles - electrons, protons, atoms, etc. - in addition to corpuscular ones, have wave properties, manifested in diffraction and interference. In quantum theory, to describe the state of micro-objects, a certain wave field is used, characterized by a wave function (Ψ-function). This function determines the probabilities of possible states of a microobject, i.e., characterizes the potential possibilities for the manifestation of certain of its properties. The law of variation of the function Ψ in space and time (Schrodinger’s equation), which allows one to find this function, plays the same role in quantum theory as Newton’s laws of motion in classical mechanics. Solving the Schrödinger equation in many cases leads to discrete possible states systems. So, for example, in the case of an atom, a series of wave functions for electrons corresponding to different (quantized) energy values is obtained. The system of atomic energy levels, calculated by the methods of quantum theory, has received brilliant confirmation in spectroscopy. The transition of an atom from the ground state corresponding to the lowest energy level E 0 to any of excited states E i occurs when a certain portion of energy E i - E 0 is absorbed. An excited atom goes to a less excited or ground state, usually by emitting a photon. In this case, the photon energy hv is equal to the difference in the energies of the atom in two states: hv = E i - E k where h is Planck’s constant (6.62·10 -27 erg·sec), v is the frequency of light.
In addition to atomic spectra, quantum theory made it possible to explain other properties of atoms. In particular, valency, the nature of the chemical bond and the structure of molecules were explained, and a theory was created periodic table elements.
Introduction
The currently existing theory of atomic structure does not answer many questions that arise during various practical and experimental work. In particular, the physical essence of electrical resistance has not yet been determined. The search for high-temperature superconductivity can only be successful if you know the essence of electrical resistance. Knowing the structure of an atom, you can understand the essence of electrical resistance. Let us consider the structure of the atom, taking into account the known properties of charges and magnetic fields. The planetary model of the atom proposed by Rutherford is closest to reality and corresponds to experimental data. However, this model only corresponds to the hydrogen atom.
CHAPTER FIRST
PROTON AND ELECTRON
1. HYDROGEN
Hydrogen is the smallest of the atoms, so its atom must contain a stable base of both the hydrogen atom and the remaining atoms. A hydrogen atom has a proton and an electron, with the electron rotating around the proton. It is believed that the charges of an electron and a proton are unit charges, i.e., minimal. The idea of an electron as a vortex ring with a variable radius was introduced by V.F. Mitkevich (L. 1). Subsequent work by Wu and some other physicists showed that the electron behaves like a rotating vortex ring, the spin of which is directed along the axis of its motion, i.e., the fact that the electron is a vortex ring was confirmed experimentally. At rest, an electron rotating around its axis does not create magnetic fields. Only when moving does an electron form magnetic lines of force.
If the charge of a proton is distributed over the surface, then, rotating together with the proton, it will rotate around only its own axis. In this case, like an electron, the charge of a proton will not form a magnetic field.
It has been experimentally established that the proton has a magnetic field. In order for a proton to have a magnetic field, its charge must be in the form of a spot on its surface. In this case, when the proton rotates, its charge will move in a circle, i.e., have a linear speed, which is necessary to obtain the proton’s magnetic field.
In addition to the electron, there is also a positron, which differs from the electron only in that its charge is positive, that is, the charge of the positron is equal to the charge of the proton both in sign and in magnitude. In other words, the positive charge of a proton is a positron, but the positron is the antiparticle of the electron and, therefore, is a vortex ring that cannot spread over the entire surface of the proton. Thus, the charge of a proton is a positron.
When an electron with a negative charge moves, the positron of the proton, under the influence of Coulomb forces, must be on the surface of the proton at a minimum distance from the electron (Fig. 1). Thus, a pair of opposite charges is formed, interconnected by the maximum Coulomb force. Precisely because the charge of a proton is a positron, its charge is equal to the electron in absolute value. When the entire charge of a proton interacts with the charge of an electron, then there is no “extra” charge of the proton that would create electrical repulsive forces between the protons.
When an electron moves around a proton in the direction shown in Fig. 1, the positive charge moves synchronously with it due to the Coulomb force. Moving charges form around themselves magnetic fields(Fig. 1). In this case, a counterclockwise magnetic field is formed around the electron, and a clockwise magnetic field is formed around the positron. As a result, a total field from two charges is formed between the charges, which prevents the electron from “falling” onto the proton.
In all figures, protons and neutrons are depicted as spheres to simplify the illustration. In reality, they should be in the form of toroidal vortex formations of the ether (L. 3).
Thus, the hydrogen atom looks like Fig. 2 A). The shape of the magnetic field of an atom corresponds to a torus-shaped magnet with magnetization along the axis of rotation of charges (Fig. 2 b).
Back in 1820, Ampere discovered the interaction of currents - the attraction of parallel conductors with a current flowing in the same direction. Later, it was experimentally determined that electric charges of the same name, moving in the same direction, are attracted to each other (L. 2).
The pinch effect also indicates that the charges should approach each other, i.e., attract each other. The pinch effect is the effect of self-contraction of a discharge, the property of an electric current channel in a compressible conducting medium to reduce its cross section under the influence of its own magnetic field generated by the current itself (L. 4).
Because electricity- any ordered movement of electric charges in space, then the trajectories of electrons and positrons and protons are current channels that can approach each other under the influence of a magnetic field generated by the charges themselves.
Consequently, when two hydrogen atoms combine into a molecule, the charges of the same name will combine into pairs and will continue to rotate in the same direction, but between protons, which will lead to the unification of their fields.
The approach of electrons and protons occurs until the moment when the force of repulsion of like charges becomes equal to the force pulling the charges together from the double magnetic field.
In Fig. 3 a), b), And V) shows the interaction of the electron and proton charges of hydrogen atoms when they combine to form a hydrogen molecule.
In Fig. Figure 4 shows a hydrogen molecule with magnetic field lines formed by field generators of two hydrogen atoms. That is, a hydrogen molecule has one dual field generator and a total magnetic flux that is 2 times greater.
We looked at how hydrogen combines into a molecule, but the hydrogen molecule does not react with other elements even when mixed with oxygen.
Now let's look at how a hydrogen molecule is divided into atoms (Fig. 5). When a hydrogen molecule interacts with electromagnetic wave the electron acquires additional energy, and this puts electrons on orbital trajectories (Fig. 5 G).
Today, superconductors are known that have zero electrical resistance. These conductors are made of atoms and can only be superconductors if their atoms are superconductors, i.e., so is the proton. The levitation of a superconductor over a permanent magnet has long been known, caused by the induction of a current in it by a permanent magnet, the magnetic field of which is directed towards the field of the permanent magnet. When the external field is removed from the superconductor, the current in it disappears. The interaction of protons with an electromagnetic wave leads to the induction of eddy currents on their surfaces. Since the protons are located next to each other, the eddy currents direct the magnetic fields towards each other, which increases the currents and their fields until the hydrogen molecule is broken into atoms (Fig. 5 G).
The release of electrons into orbital trajectories and the emergence of currents that break the molecule occur simultaneously. When hydrogen atoms fly away from each other, the eddy currents disappear, and the electrons remain on orbital trajectories.
Thus, based on known physical effects, we have obtained a model of the hydrogen atom. Wherein:
1. Positive and negative charges in an atom serve to produce magnetic field lines, which, as is known from classical physics, are formed only when charges move. Magnetic field lines determine all intraatomic, interatomic and molecular bonds.
2. The entire positive charge of the proton - the positron - interacts with the charge of the electron, creates the maximum Coulomb force of attraction for the electron, and the equality of the charges in absolute value excludes the proton from having repulsive forces for neighboring protons.
3. In practice, the hydrogen atom is a proton-electron magnetic generator (PEMG), which works only when the proton and electron are together, i.e. the proton-electron pair must always be together.
4. When a hydrogen molecule is formed, electrons pair up and rotate together between atoms, creating a common magnetic field that keeps them paired. Proton positrons also pair up under the influence of their magnetic fields and pull together protons, forming a hydrogen molecule or any other molecule. Paired positive charges are the main determining force in molecular bonding, since positrons are directly associated with protons and are inseparable from protons.
5. Molecular bonds of all elements occur in a similar way. The connection of atoms into molecules of other elements is ensured by valence protons with their electrons, i.e. valence electrons are involved both in the connection of atoms into molecules and in the breaking of molecular bonds. Thus, each connection of atoms into a molecule is provided by one proton-electron valence pair (VPEP) from each atom per molecular bond. VPES always consist of a proton and an electron.
6. When a molecular bond is broken main role the electron plays because, entering an orbital trajectory around its proton, it pulls the proton’s positron out of the pair located between the protons to the “equator” of the proton, thereby ensuring the rupture of the molecular bond.
7. When a hydrogen molecule and molecules of other elements are formed, a double PEMG is formed.
The sizes and masses of atoms are small. The radius of the atoms is 10 -10 m, and the radius of the nucleus is 10 -15 m. The mass of an atom is determined by dividing the mass of one mole of atoms of the element by the number of atoms in 1 mole (N A = 6.02·10 23 mol -1). The mass of atoms varies within the range of 10 -27 ~ 10 -25 kg. Typically, the mass of atoms is expressed in atomic mass units (amu). For a.u.m. 1/12 of the mass of an atom of the carbon isotope 12 C is taken.
The main characteristics of an atom are the charge of its nucleus (Z) and mass number (A). The number of electrons in an atom is equal to the charge of its nucleus. The properties of atoms are determined by the charge of their nuclei, the number of electrons and their state in the atom.
Basic properties and structure of the nucleus (theory of the composition of atomic nuclei)
1. The atomic nuclei of all elements (except hydrogen) consist of protons and neutrons.
2. The number of protons in the nucleus determines the value of its positive charge (Z). Z- serial number of a chemical element in the periodic system of Mendeleev.
3. The total number of protons and neutrons is the value of its mass, since the mass of an atom is mainly concentrated in the nucleus (99.97% of the mass of the atom). Nuclear particles- protons and neutrons - are united under the general name nucleons(from the Latin word nucleus, which means “kernel”). The total number of nucleons corresponds to the mass number, i.e. its atomic mass A rounded to the nearest whole number.
Cores with the same Z, but different A are called isotopes. Cores that, with the same A have different Z, are called isobars. In total, about 300 stable isotopes of chemical elements and more than 2000 natural and artificially produced radioactive isotopes are known.
4. Number of neutrons in the nucleus N can be found from the difference between the mass number ( A) and serial number ( Z):
5. The size of the kernel is characterized core radius, which has a conditional meaning due to the blurring of the core boundary.
The density of nuclear matter is of the order of magnitude 10 17 kg/m 3 and is constant for all nuclei. It significantly exceeds the densities of the densest ordinary substances.
The proton-neutron theory made it possible to resolve the previously arising contradictions in ideas about the composition of atomic nuclei and its relationship with the atomic number and atomic mass.
Nuclear binding energy is determined by the amount of work that needs to be done to split a nucleus into its constituent nucleons without imparting kinetic energy to them. From the law of conservation of energy it follows that during the formation of a nucleus the same energy must be released as must be expended during the splitting of the nucleus into its constituent nucleons. The binding energy of a nucleus is the difference between the energy of all the free nucleons that make up the nucleus and their energy in the nucleus.
When a nucleus is formed, its mass decreases: the mass of the nucleus is less than the sum of the masses of its constituent nucleons. The decrease in the mass of the nucleus during its formation is explained by the release of binding energy. If W sv is the amount of energy released during the formation of a nucleus, then the corresponding mass Dm, equal to
called mass defect and characterizes the decrease in the total mass during the formation of a nucleus from its constituent nucleons. One atomic mass unit corresponds to atomic energy unit(a.u.e.): a.u.e.=931.5016 MeV.
Specific nuclear binding energy w The binding energy per nucleon is called: w sv= 
. Magnitude w averages 8 MeV/nucleon. As the number of nucleons in the nucleus increases, the specific binding energy decreases.
Criterion for the stability of atomic nuclei is the ratio between the number of protons and neutrons in a stable nucleus for given isobars. ( A= const).
Nuclear forces
1. Nuclear interaction indicates that there are special nuclear forces, not reducible to any of the types of forces known in classical physics(gravitational and electromagnetic).
2. Nuclear forces are short-range forces. They appear only at very small distances between nucleons in the nucleus of the order of 10-15 m. The length (1.5 x 2.2)10-15 m is called range of nuclear forces.
3. Nuclear forces are detected charge independence: The attraction between two nucleons is the same regardless of the charge state of the nucleons - proton or nucleon. The charge independence of nuclear forces is evident from a comparison of binding energies in mirror cores. This is the name given to nuclei in which the same total number nucleons, but the number of protons in one is equal to the number of neutrons in the other. For example, helium nuclei 
heavy hydrogen tritium - .
4. Nuclear forces have a saturation property, which manifests itself in the fact that a nucleon in a nucleus interacts only with a limited number of neighboring nucleons closest to it. This is why there is a linear dependence of the binding energies of nuclei on their mass numbers (A). Almost complete saturation of nuclear forces is achieved in the a-particle, which is a very stable formation.
Radioactivity, g-radiation, a and b - decay
1.Radioactivity is the transformation of unstable isotopes of one chemical element into isotopes of another element, accompanied by the emission of elementary particles, nuclei or hard x-rays. Natural radioactivity called radioactivity observed in naturally occurring unstable isotopes. Artificial radioactivity called the radioactivity of isotopes obtained as a result of nuclear reactions.
2. Typically, all types of radioactivity are accompanied by the emission of gamma radiation - hard, short-wave electric wave radiation. Gamma radiation is the main form of reducing the energy of excited products of radioactive transformations. A nucleus undergoing radioactive decay is called maternal; emerging subsidiary the nucleus, as a rule, turns out to be excited, and its transition to the ground state is accompanied by the emission of a g-photon.
3. Alpha decay called the emission of a-particles by the nuclei of some chemical elements. Alpha decay is a property of heavy nuclei with mass numbers A>200 and nuclear charges Z>82. Inside such nuclei, the formation of isolated a-particles occurs, each consisting of two protons and two neutrons, i.e. an atom of an element is formed, shifted in the table of the periodic system of elements D.I. Mendeleev (PSE) two cells to the left of the original radioactive element with a mass number less than 4 units(Soddy-Faience rule): 
4. The term beta decay refers to three types of nuclear transformations: electronic(b-) and positronic(b+) decays, as well as electronic capture.
b-decay occurs predominantly in nuclei relatively rich in neutrons. In this case, the neutron of the nucleus decays into a proton, electron and antineutrino () with zero charge and mass.
During b-decay, the mass number of the isotope does not change, since the total number of protons and neutrons is maintained, and the charge increases by 1. Therefore, the atom of the resulting chemical element is shifted by the PSE one cell to the right from the original element, but its mass number does not change(Soddy-Faience rule):
b+- decay occurs predominantly in relatively proton-rich nuclei. In this case, the proton of the nucleus decays into a neutron, positron and neutrino ().
.
During b+ decay, the mass number of the isotope does not change, since the total number of protons and neutrons is maintained, and the charge decreases by 1. Therefore, the atom of the resulting chemical element is shifted by the PSE one cell to the left from the original element, but its mass number does not change(Soddy-Faience rule):
5. In the case of electron capture, the transformation consists of the disappearance of one of the electrons in the layer closest to the nucleus. A proton, turning into a neutron, “captures” an electron; This is where the term “electronic capture” comes from. Electronic capture, in contrast to b±-capture, is accompanied by characteristic X-ray radiation.
6. b-decay occurs in naturally radioactive as well as artificially radioactive nuclei; b+ decay is characteristic only of the phenomenon of artificial radioactivity.
7. g-radiation: when excited, the nucleus of an atom emits electromagnetic radiation with a short wavelength and high frequency, which has greater rigidity and penetrating power than x-rays. As a result, the energy of the nucleus decreases, but the mass number and charge of the nucleus remain unchanged. Therefore, the transformation of a chemical element into another is not observed, and the nucleus of the atom passes into a less excited state.
Atom. An idea of the structure of the atom. Electrons, protons, neutrons
Atom - an elementary particle of a substance (chemical element), consisting of a certain set of protons and neutrons (atomic nucleus), and electrons.
The nucleus of an atom consists of protons (p+) and neutrons (n0).Number of protons N(p+) equal to the charge of the nucleus(Z) And element serial number in the natural series of elements (and in the periodic table of elements). The sum of the number of neutrons N(n0), denoted simply by the letter N, and the number of protons Z is called the mass number and denoted by the letter A. The electron shell of an atom consists of electrons moving around the nucleus(e-). Number of electrons N(e-) in the electron shell of a neutral atom is equal to number of protons Z at its core.
An idea of the modern quantum mechanical model of the atom. Characteristics of the state of electrons in an atom using a set of quantum numbers, their interpretation and permissible values
Atom – a microcosm in which the laws of quantum mechanics apply.
The wave process of electron motion in an atom around the nucleus is described using the wave function psi (ψ), which must have three quantization parameters (3 degrees of freedom).
Physical meaning – three-dimensional amplitude el. waves.
n – principal quantum number, character. energetic level in an atom.
l – secondary (orbital number) l=0…n-1, characterizes the energy. sublevels in the atom and the shape of the atomic orbital.
m l – magnetic number ml= -l… +l, characterizes the orientation of the element in the l.p.
ms is the spin number. Spanish Because each electron has its own moment of motion
The sequence of filling energy levels and sublevels with electrons in multielectron atoms. Pauli's principle. Hund's rule. The principle of minimum energy.
Etc. Gunda: filling occurs sequentially in such a way that the sum of spin numbers (momentum of motion) is maximum.
Pauli principle: in an atom there cannot be 2 electrons that have all 4 quanta. The numbers would be the same
Xn– max number of el. on energy ur.
Starting from the 3rd period, a lag effect is observed, which is explained by the principle lowest energy: the formation of the electron shell of an atom occurs in such a way that the el. occupy an energetically favorable position when the binding energy with the nucleus is the maximum possible, and the electron’s own energy is the minimum possible.
Etc. Klichevsky– the most energetically beneficial are those in cats. the sum of quantum numbers n and l tends to min.
Ionization energy and electron affinity energy. The nature of their changes by periods and groups of D.I. Mendeleev’s periodic system. Metals and non-metals.
Atomic ionization energy- The energy required to remove an electron from an unexcited atom is called the first ionization energy (potential).
Electron affinity- The energetic effect of adding an electron to a neutral atom is called electron affinity (E).
Ionization energy increases in periods from alkali metals to noble gases and decreases in groups from top to bottom.
For elements of main subgroups electron affinity increases in periods from left to right and decreases in groups from top to bottom.
Electronegativity of chemical elements. The nature of changes in electronegativity by periods and groups of D.I. Mendeleev’s periodic system. The concept of oxidation state.
Electronegativity– ability of atom chemical el. in a compound attract electrons to itself
Evaluation methods:
EO=I+E(kJ/mol) - half the sum of ionization and affinity energies (according to Maliken)
Pauling relative scale
Using the relative scale of e.o. and having accepted e.o. F= 4 in the period with increasing nuclear charge e.o. enlarge and increase mute. St.
In the group, an increase in nuclear charge is accompanied by a decrease in e.o. and increased met. St.
Oxidation state (oxidation number)– the imaginary charge of an atom of an electronic compound, which is determined from the assumption that the compound consists of ions
S.o. simple substances =0
С.о oxygen = -2 (excl. Peroxides H2O2(-1) and compounds with fluorine)
S.o. hydrogen and alkali metals = +1
Netrit S.o. have only mute and only one
In any ion, the algebraic sum of all s.o. = ion charge, and in neutral molecules = 0
If a chemical compound consists of meth and non-meth, then meth +, non-meth –
If the chemical combination of 2x is neutral, then negative s.o. has the one with the cat > e.o.
Periodic law and periodic system of elements by D.I. Mendeleev. Periods, groups and subgroups of the periodic system. Relationship between the periodic system and the structure of atoms. Electronic families of elements.
wording periodic law is this:
“the properties of chemical elements (i.e., the properties and form of the compounds they form) are periodically dependent on the charge of the nucleus of the atoms of the chemical elements.”
Mendeleev's periodic table consists of 8 groups and 7 periods.
The vertical columns of a table are called groups. The elements within each group have similar chemical and physical properties. This is explained by the fact that elements of the same group have similar electronic configurations of the outer layer, the number of electrons on which is equal to the group number. Wherein the group is divided into main and secondary subgroups.
To Main subgroups include elements whose valence electrons are located on the outer ns- and np-sublevels. In Side subgroups include elements whose valence electrons are located on the outer ns-sublevel and the inner (n - 1) d-sublevel (or (n - 2) f-sublevel).
All elements in the periodic table, depending on which sublevel(s-, p-, d- or f-) valence electrons are classified into: s-elements (elements of the main subgroups of groups I and II), p-elements (elements of the main subgroups III - VII groups), d-elements (elements of side subgroups), f-elements (lanthanides, actinides).
The horizontal rows of the table are called periods. The elements in the periods differ from each other, but what they have in common is that the last electrons are at the same energy level (the main quantum number n is the same).
The name “atom” is translated from Greek as “indivisible.” Everything around us - solids, liquids and air - is built from billions of these particles.
The appearance of the version about the atom
Atoms first became known in the 5th century BC, when the Greek philosopher Democritus proposed that matter consists of tiny moving particles. But then it was not possible to verify the version of their existence. And although no one could see these particles, the idea was discussed, because this was the only way scientists could explain the processes occurring in the real world. Therefore, they believed in the existence of microparticles long before the time when they could prove this fact.
Only in the 19th century. they began to be analyzed as the smallest components of chemical elements, having specific properties of atoms - the ability to enter into compounds with others in a strictly designated quantity. At the beginning of the 20th century, it was believed that atoms were the smallest particles of matter, until it was proven that they consist of even smaller units.
What does a chemical element consist of?
An atom of a chemical element is a microscopic building block of matter. The defining feature of this microparticle was molecular mass atom. Only the discovery of Mendeleev's periodic law substantiated that their types represent diverse forms of a single matter. They are so small that they cannot be seen using conventional microscopes, only the most powerful ones. electronic devices. For comparison, a hair on a person's arm is a million times wider.
The electronic structure of an atom has a nucleus consisting of neutrons and protons, as well as electrons, which orbit around the center in constant orbits, like planets around their stars. All of them are held together by electromagnetic force, one of the four main ones in the universe. Neutrons are particles with a neutral charge, protons have a positive charge, and electrons have a negative charge. The latter are attracted to positively charged protons, so they tend to remain in orbit.
Atomic structure
In the central part there is a nucleus that fills a minimal part of the entire atom. But research shows that almost the entire mass (99.9%) is located in it. Each atom contains protons, neutrons, and electrons. The number of spinning electrons in it is equal to the positive central charge. Particles with the same nuclear charge Z, but different atomic mass A and the number of neutrons in the nucleus N are called isotopes, and with the same A and different Z and N are called isobars. An electron is a minimal particle of matter with a negative electric charge e=1.6·10-19 coulombs. The charge of an ion determines the number of electrons lost or gained. The process of metamorphosis of a neutral atom into a charged ion is called ionization.
New version of the atom model
Physicists have now discovered many other elementary particles. The electronic structure of the atom has a new version.
It is believed that protons and neutrons, no matter how small they are, consist of the smallest particles called quarks. They constitute a new model for the construction of the atom. Just as scientists used to collect evidence for the existence of the previous model, today they are trying to prove the existence of quarks.
RTM - the device of the future
Modern scientists can see atomic particles of matter on a computer monitor, and also move them along the surface using a special instrument called a scanning tunneling microscope (RTM).
This computerized a tool with a tip that moves very gently near the surface of the material. As the tip moves, electrons move through the gap between the tip and the surface. Although the material appears perfectly smooth, it is actually rough at the atomic level. The computer makes a map of the surface of the substance, creating an image of its particles, and scientists can thus see the properties of the atom.
Radioactive particles
Negatively charged ions circle around the nucleus at a fairly large distance. The structure of an atom is such that the whole of it is truly neutral and has no electrical charge, because all its particles (protons, neutrons, electrons) are in balance.
A radioactive atom is an element that can be easily split. Its center consists of many protons and neutrons. The only exception is the diagram of the hydrogen atom, which has one single proton. The nucleus is surrounded by a cloud of electrons, and it is their attraction that makes it rotate around the center. Protons with the same charge repel each other.
This is not a problem for most small particles, which have several of them. But some of them are unstable, especially the larger ones, such as uranium, which has 92 protons. Sometimes its center cannot withstand such a load. They are called radioactive because they emit several particles from their core. After the unstable nucleus gets rid of protons, the remaining ones form a new daughter. It can be stable depending on the number of protons in the new nucleus, or it can divide further. This process continues until a stable daughter nucleus remains.
Properties of atoms
The physicochemical properties of an atom naturally change from one element to another. They are determined by the following main parameters.
Atomic mass. Since the main place of microparticles is occupied by protons and neutrons, their sum determines the number, which is expressed in atomic mass units (amu) Formula: A = Z + N.
Atomic radius. The radius depends on the location of the element in the periodic system, chemical bonding, the number of neighboring atoms and quantum mechanical action. The radius of the core is one hundred thousand times smaller than the radius of the element itself. An atomic structure can lose electrons and become a positive ion or add electrons and become a negative ion.
In Mendeleev, any chemical element takes its established place. In the table, the size of an atom increases as you move from top to bottom and decreases as you move from left to right. Following from this, the smallest element is helium, and the largest is cesium.
Valence. The outer electron shell of an atom is called the valence shell, and the electrons in it are given the corresponding name - valence electrons. Their number determines how the atom connects to the others through a chemical bond. The method used to create the latter microparticles is to fill their outer valence shells.
Gravity, attraction, is the force that keeps the planets in orbit; because of it, objects released from the hands fall to the floor. A person notices gravity more, but the electromagnetic effect is many times more powerful. The force that attracts (or repels) charged particles in an atom is 1000,000,000,000,000,000,000,000,000,000,000 times more powerful than gravity within it. But in the center of the core there is even more mighty force, capable of holding protons and neutrons together.
Reactions in nuclei create energy as in nuclear reactors, where atoms are split. The heavier the element, the greater the number of particles its atoms are made of. If folded total protons and neutrons in an element, we find out its mass. For example, Uranium, the heaviest element found in nature, has atomic mass 235 or 238.
Dividing an atom into levels
An atom is the amount of space around the nucleus where an electron is in motion. There are 7 orbitals in total, corresponding to the number of periods in the periodic table. The more distant the electron is from the nucleus, the more significant energy reserve it has. The period number indicates the number around its core. For example, Potassium is a period 4 element, which means it has 4 atomic energy levels. The number of a chemical element corresponds to its charge and the number of electrons around the nucleus.
Atom is a source of energy
Probably the most famous scientific formula was discovered by the German physicist Einstein. It states that mass is nothing more than a form of energy. Based on this theory, you can turn matter into energy and calculate using the formula how much of it you can get. The first practical result of this transformation was atomic bombs, which were first tested in the Los Alamos desert (USA) and then exploded over Japanese cities. And although only the seventh part explosive turned into energy, the destructive power of the atomic bomb was terrible.
In order for the core to release its energy, it must collapse. To split it, it is necessary to act with a neutron from the outside. Then the nucleus splits into two other, lighter ones, providing a huge release of energy. The decay leads to the release of other neutrons, and they continue to split other nuclei. The process turns into chain reaction, resulting in creating great amount energy.
Pros and cons of using nuclear reaction in our time
Humanity is trying to tame the destructive force that is released during the transformation of matter. nuclear power plants. Here the nuclear reaction does not occur in the form of an explosion, but as a gradual release of heat.
Production atomic energy has its pros and cons. According to scientists, to maintain our civilization at high level, it is necessary to use this huge source of energy. But it should also be taken into account that even the most modern developments cannot guarantee complete safety nuclear power plants. In addition, the energy obtained during the production process, if not properly stored, can affect our descendants for tens of thousands of years.
After the accident at the Chernobyl nuclear power plant, everything more people considers the production of nuclear energy very dangerous for humanity. The only safe power plant of this kind is the Sun with its enormous nuclear energy. Scientists are developing all kinds of models of solar panels, and perhaps in the near future humanity will be able to provide itself with safe nuclear energy.
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