What is the charge of an atom z. Atomic nucleus: charge of the nucleus

CHARGE THE CORE

Moseley's Law. The electric charge of the nucleus is formed by the protons that make up its composition. Number of protons Z call it the charge, meaning that the absolute value of the nuclear charge is Ze. The charge of the nucleus coincides with the serial number Z element in the periodic table of elements of Mendeleev. For the first time the charges of atomic nuclei were determined by the English physicist Moseley in 1913. By measuring the wavelength with a crystal λ characteristic x-ray for atoms of some elements, Moseley discovered a regular change in wavelength λ at the elements following each other in the periodic table (Figure 2.1). Moseley interpreted this observation as addiction λ from some constant of the atom Z changing by one from element to element and equal to one for hydrogen:

where and are constants. From experiments on the scattering of X-ray quanta by atomic electrons and α -particles with atomic nuclei it was already known that the charge of the nucleus is approximately equal to half the atomic mass and, therefore, is close to the ordinal number of the element. Since the emission of characteristic X-rays is a consequence of electrical processes in the atom, Moseley concluded that the constant of atoms found in his experiments, which determines the wavelength of characteristic X-ray radiation and coincides with the ordinal number of the element, can only be the charge of the atomic nucleus (Moseley's law).

Fig. 2.1. X-ray spectra of atoms of neighboring elements obtained by Moseley

The measurement of the wavelengths of X-rays is performed with great accuracy, so that, based on Moseley's law, the belonging of an atom to a chemical element is established absolutely reliably. At the same time, the fact that the constant Z in the last equation is the charge of the nucleus, although it is justified by indirect experiments, ultimately rests on a postulate - Moseley's law. Therefore, after Moseley's discovery, the nuclear charges were measured many times in scattering experiments α -particles based on Coulomb's law. In 1920, Chadwig refined the method for measuring the proportion of scattered α -particles and received the charges of the nuclei of atoms of copper, silver and platinum (see table 2.1). Chadwig's data leaves no doubt about the validity of Moseley's law. In addition to the indicated elements, the charges of the nuclei of magnesium, aluminum, argon and gold were also determined in the experiments.

Table 2.1. Results of Chadwick's experiments

Definitions. After Moseley's discovery, it became clear that the main characteristic of an atom is the nuclear charge, and not its atomic mass, as the chemists of the 19th century assumed, because the nuclear charge determines the number of atomic electrons, and therefore the chemical properties of atoms. The reason for the difference between the atoms of chemical elements is precisely that their nuclei have different number protons in its composition. On the contrary, a different number of neutrons in the nuclei of atoms with the same number of protons does not in any way change the chemical properties of atoms. Atoms that differ only in the number of neutrons in nuclei are called isotopes chemical element.

Structure atom- this is one of the basic topics of the course of chemistry, which is based on the knowledge to use the table "Periodic table of chemical elements of DI Mendeleev." These are not only chemical elements classified and located according to certain laws, but also a storehouse of information, including about the structure. atom... Knowing the peculiarities of reading this unique reference material, it is allowed to give a complete solid and quantitative collation to an atom.

You will need

D.I. Mendeleev's table

Instructions

1. In the table of D.I. Mendeleev, as in a multi-storey apartment building"Live" chemical elements, all of which take their own apartment... Thus, each of the elements has a certain serial number specified in the table. The numbering of chemical elements starts from left to right, and from above. In the table, horizontal rows are called periods, and vertical columns are called groups. This is important, since by the number of the group or period it is also allowed to give a collation to some parameters. atom .

2. An atom is a chemically indivisible particle, but at the same time it consists of more small combined parts, to which it is allowed to include protons (correctly charged particles), electrons (negatively charged) and neutrons (neutral particles). The bulk atom focused in the nucleus (due to protons and neutrons), around which electrons revolve. In the aggregate, the atom is electrically neutral, that is, it contains the number of correct charges coincides with the number of negative ones, therefore, the number of protons and electrons is identical. Correct core charge atom takes place to be just due to protons.

3. It must be remembered that the ordinal number of a chemical element quantitatively coincides with the charge of the nucleus atom... Consequently, in order to determine the charge of the nucleus atom you need to see what number a given chemical element is under.

4. Example No. 1. Determine the charge of the nucleus atom carbon (C). We begin to study the chemical element carbon, focusing on the table of D.I. Mendeleev. Carbon is in "apartment" No. 6. Consequently, it has a nucleus charge of +6 due to 6 protons (correctly charged particles), which are located in the nucleus. Considering that the atom is electrically neutral, then there will also be 6 electrons.

5. Example No. 2. Determine the charge of the nucleus atom aluminum (Al). Aluminum has a serial number - No. 13. Consequently, the charge of the nucleus atom aluminum +13 (due to 13 protons). There will also be 13 electrons.

6. Example No. 3. Determine the charge of the nucleus atom silver (Ag). Silver has a serial number - No. 47. This means that the charge of the nucleus atom silver + 47 (due to 47 protons). There are also 47 electrons.

An atom of a chemical element consists of kernels and electronic shell. The nucleus is the central part of the atom, in which approximately every of its mass is concentrated. Unlike the electron shell, the nucleus has the correct charge .

You will need

Atomic number of a chemical element, Moseley's law

Instructions

1. The nucleus of an atom consists of 2 types of particles - protons and neutrons. Neutrons are electrically neutral particles, that is, their electrical charge equal to zero... Protons are positively charged particles and their electrical charge is +1.

2. In this way, charge kernels is equal to the number of protons. In turn, the number of protons in the nucleus is equal to the nuclear number of a chemical element. For example, the nuclear number of hydrogen is 1, that is, the hydrogen nucleus consists of one proton has charge+1. The nuclear number of sodium is 11, charge his kernels is +11.

3. With alpha decay kernels its nuclear number is reduced by two due to the emission of an alpha particle ( kernels atom of helium). Thus, the number of protons in a nucleus that has undergone alpha decay also decreases by two. Beta decay can occur in 3 different types... In the case of beta-minus decay, a neutron turns into a proton when an electron and an antineutrino are emitted. Then charge kernels increases by unity. In the case of beta-plus decay, the proton converts into a neutron, positron and neutrino, charge kernels decreases by one. In the case of electron capture charge kernels also decreases by one.

4. Charge kernels it is also possible to determine the characteristic radiation of the atom from the frequency of the spectral lines. According to Moseley's law: sqrt (v / R) = (ZS) / n, where v is the spectral frequency of the characteristic radiation, R is the Rydberg continuous, S is the screening continuous, n is the fundamental quantum number. Thus, Z = n * sqrt ( v / r) + s.

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An atom is the smallest particle of the whole element, which carries its chemical properties. Both existence and the structure of the atom have been the subject of reasoning and comprehension since ancient times. It was found that the structure of atoms is akin to the structure of the Clear System: in the center there is a nucleus, which takes up a lot of space, but has focused in itself about the entire mass; "planets" revolve around it - electrons carrying negative charges... And how is it allowed to detect a charge kernels atom?

Instructions

1. Every atom is electrically neutral. But, from the fact that electrons carry negative charges, they must be balanced by opposite charges. And there is. Positive charges are carried by particles called "protons" located in the nucleus of an atom. The proton is much bulkier than the electron: it weighs the same as 1836 electrons!

2. The most primitive case is the hydrogen atom of the first element Periodic table... Looking at the table, you can make sure that it takes the first place, and its nucleus consists of an exceptional proton, around which an exceptional electron revolves. It follows from this that the charge kernels a hydrogen atom is +1.

3. The nuclei of other elements are more closely composed not only of protons, but also of the so-called "neutrons". As you can easily understand from the name itself, neutrons do not carry any charge at all - neither negative nor correct. Consequently, remember: no matter how many neutrons are included in the nuclear kernels, they affect only its mass, but not the charge.

4. Consequently, the magnitude of the positive charge kernels atom depends only on how many protons it contains. But from the fact that, as noted more closely, the atom is electrically neutral, its nucleus should contain as many protons as electrons revolve around kernels... The number of protons is determined by the ordinal number of the element in the periodic table.

5. Consider several elements. Let's say that the famous and vital oxygen is in "cell" number 8. Consequently, its nucleus contains 8 protons, and the charge kernels will be +8. Steel occupies "cell" number 26, and, accordingly, has a charge kernels+26. And a decent metal - gold, with serial number 79 - will have exactly the same charge kernels(79), with a + sign. Accordingly, the oxygen atom contains 8 electrons, the iron atom - 26, and the gold atom - 79.

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IN ordinary conditions the atom is electrically neutral. In this case, the nucleus of an atom, consisting of protons and neutrons, is charged approvingly, and electrons carry a negative charge. With an excess or lack of electrons, the atom turns into an ion.

Instructions

1. Every chemical element has its own unique nuclear charge. It is the charge that determines the number of the element in the periodic table. So, the hydrogen nucleus has a charge of +1, helium +2, lithium +3, beryllium +4, etc. Thus, if we carry an element, the charge of the nucleus of its atom can be determined from the periodic table.

2. Since the atom is electrically neutral under ordinary conditions, the number of electrons corresponds to the charge of the atom's nucleus. The negative charge of the electrons is offset by the positive charge of the nucleus. Electrostatic forces keep the electron clouds close to the atom, which makes it stable.

3. Under the influence of certain conditions, it is allowed to take away electrons from an atom or add additional electrons to it. If you take an electron away from an atom, the atom turns into a cation — a properly charged ion. With an excess of electrons, the atom becomes an anion - a negatively charged ion.

4. Chemical compounds can be of molecular or ionic nature. Molecules are also electrically neutral, and ions carry a certain charge. So, the ammonia NH3 molecule is neutral, but the ammonium ion NH4 + is charged correctly. The bonds between the atoms in the ammonia molecule are covalent, formed by the exchange type. The fourth hydrogen atom is attached via the donor-acceptor mechanism, this is also covalent bond... Ammonium is formed by the interaction of ammonia with acid solutions.

5. The main thing to understand is that the charge of the element's nucleus does not depend on chemical reincarnations. No matter how many electrons you add or subtract, the charge of the nucleus remains the same. For example, the O atom, the O- anion and the O + cation have the same nuclear charge +8. In this case, the atom has 8 electrons, the anion 9, the cation - 7. The nucleus itself can be changed only through nuclear metamorphosis.

6. Particularly frequent view nuclear reactions- radioactive decay, which can occur in the natural environment. The nuclear mass of elements that undergo such decay in nature is contained in square brackets... This means that the mass number is not constant, changes over time.

In the periodic table of elements D.I. Mendeleev's silver has a serial number 47 and the designation "Ag" (argentum). The name of this metal may have come from the Latin "argos", which means "white", "shining".

Instructions

1. Silver was known to society as early as the 4th millennium BC. In ancient Egypt it was even called "white gold". This expensive metal occurs in nature both in native form and in the form of compounds, say, sulfides. Silver nuggets are heavy and often contain admixtures of gold, mercury, copper, platinum, antimony and bismuth.

2. Chemical properties silver.Silver belongs to the group of transition metals and has all the properties of metals. However, the chemical activity of silver is small - in the electrochemical series of metal voltages, it is located to the right of hydrogen, approximately at the very end. In compounds, silver most often exhibits an oxidation state of +1.

3. Under ordinary conditions, silver does not react with oxygen, hydrogen, nitrogen, carbon, silicon, but interacts with sulfur, forming silver sulfide: 2Ag + S = Ag2S. When heated, silver interacts with halogens: 2Ag + Cl2 = 2AgCl ?.

4. Soluble silver nitrate AgNO3 is used for the high-quality determination of halide ions in solution - (Cl-), (Br-), (I-): (Ag +) + (Hal -) = AgHal ?. For example, when interacting with chlorine anions, silver gives insoluble white sediment AgCl ?.

5. The reason for the gradual darkening of silver items is explained by the fact that silver reacts with hydrogen sulfide in the air. As a result, an Ag2S film is formed on the metal surface: 4Ag + 2H2S + O2 = 2Ag2S + 2H2O.

6. How does silver interact with acids? With dilute hydrochloric and sulfuric acids, silver, like copper, does not interact, because it is a metal of low activity and cannot displace hydrogen from them. Oxidizing acids, nitric and concentrated sulfuric acids, dissolve silver: 2Ag + 2H2SO4 (conc.) = Ag2SO4 + SO2? + 2H2O; Ag + 2HNO3 (conc.) = AgNO3 + NO2? + H2O; 3Ag + 4HNO3 (dil.) = 3AgNO3 + NO? + 2H2O.

7. If alkali is added to the silver nitrate solution, you get a dark chestnut precipitate of silver oxide Ag2O: 2AgNO3 + 2NaOH = Ag2O? + 2NaNO3 + H2O.

8. Like monovalent copper compounds, insoluble precipitates AgCl and Ag2O are able to dissolve in ammonia solutions, giving complex compounds: AgCl + 2NH3 = Cl; Ag2O + 4NH3 + H2O = 2OH. The latter compound is often used in organic chemistry in the "silver mirror" reaction - a high-quality reaction to an aldehyde group.

Carbon is one of the chemical elements that has the symbol C in the periodic table. Its serial number is 6, its nuclear mass is 12.0107 g / mol, and the radius of the atom is 91 pm. Carbon owes its name to Russian chemists, who first gave the element the name "ugletvor", after which it was transformed into the present one.

Instructions

1. Carbon has been used in industry since ancient times, when blacksmiths used it in smelting metals. Two allotropic modifications of a chemical element are widely known - diamond, used in jewelry and industrial sectors, as well as graphite, for the discovery of which he was shortly awarded Nobel Prize... Antoine Lavoisier spent his first skills with the so-called pure coal, after which its properties were partially studied by a group of scientists - Guiton de Morveaux, Lavoisier himself, Berthollet and Furcroix, who described their skill in the book "Method of chemical nomenclature".

2. For the first time, free carbon was brought out by the Briton Tennant, the one who passed phosphorus vapors over hot chalk and received calcium phosphate together with carbon. The skills of the British staff were continued by the Frenchman Guiton de Morveaux. He carefully heated the diamond, eventually turning it into graphite and later into carbonic acid.

3. Carbon has quite a variety of physical properties because of education chemical bonds different types... It is more closely known that this chemical element is continuously formed in the lower layers of the stratosphere, and its properties have provided carbon a place in nuclear power plants and in nuclear hydrogen bombs since the 1950s.

4. Physicists distinguish several forms or structures of carbon: tetric, trigonal and diagonal. It also has several crystalline variations - diamond, graphene, graphite, carbyne, lonsdaleite, nanodiamond, fullerene, fullerite, carbon fiber, nanofibers and nanotubes. Amorphous carbon also has forms: activated and charcoal, fossil coal or anthracite, coal or petroleum coke, glassy carbon, carbon black, soot and carbon nanofilm. Physicists also share colaster variations - astralenes, dicarbons and carbon nanocones.

5. Carbon is quite inert in the absence of extreme temperatures, and when their upper threshold is reached, it can combine with other chemical elements, exhibiting strong reducing properties.

6. Probably the most famous use of carbon is in the pencil industry, where it is mixed with clay for less brittleness. It is also used as a lubricant with a lot of high or low temperatures, and the high melting point makes it possible to produce strong crucibles from carbon for pouring metals. Graphite also charmingly conducts electricity, which gives great prospects for its use in electronics.

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Note!
In the table of D.I. Mendeleev, in one cell for the entire chemical element, two numerical values are indicated. Do not confuse the ordinal number and the relative nuclear mass of an element.

Investigating the passage of an α-particle through a thin gold foil (see Section 6.2), E. Rutherford came to the conclusion that an atom consists of a heavy positive charged nucleus and electrons surrounding it.

Core called the central part of the atom,in which almost all the mass of the atom and its positive charge are concentrated.

IN atomic composition are included elementary particles : protons and neutrons (nucleons from the Latin word nucleus- core). This proton-neutron model of the nucleus was proposed by a Soviet physicist in 1932 by D.D. Ivanenko. The proton has a positive charge e + = 1.06 · 10 -19 C and rest mass m p= 1.673 · 10 -27 kg = 1836 m e... Neutron ( n) Is a neutral particle with rest mass m n= 1.675 · 10 -27 kg = 1839 m e(where the electron mass m e, is equal to 0.91 · 10 –31 kg). In fig. 9.1 shows the structure of the helium atom according to the concepts of the end of XX - early XXI in.

Core charge is equal to Ze where e Is the proton charge, Z- charge number equal to ordinal number chemical element in the periodic table of elements of Mendeleev, i.e. the number of protons in the nucleus. The number of neutrons in the nucleus is denoted N... Usually Z > N.

Currently known kernels Z= 1 to Z = 107 – 118.

The number of nucleons in the nucleus A = Z + N called massive number ... Kernels with the same Z but different BUT are called isotopes... Kernels that, with the same A have different Z are called isobars.

The nucleus is denoted by the same symbol as the neutral atom, where X- symbol of a chemical element. For example: hydrogen Z= 1 has three isotopes: - protium ( Z = 1, N= 0), - deuterium ( Z = 1, N= 1), - tritium ( Z = 1, N= 2), tin has 10 isotopes, etc. In the overwhelming majority, isotopes of one chemical element have the same chemical and similar physical properties. In total, about 300 stable isotopes are known and more than 2000 natural and artificially obtained radioactive isotopes.

The size of the nucleus is characterized by the radius of the nucleus, which has a conventional meaning due to the blurring of the nucleus boundary. Even E. Rutherford, analyzing his experiments, showed that the size of the nucleus is approximately 10 -15 m (the size of an atom is 10 -10 m). There is an empirical formula for calculating the radius of the kernel:

(9.1.1)

Where R 0 = (1.3 - 1.7) · 10 –15 m. From this it can be seen that the volume of the nucleus is proportional to the number of nucleons.

The density of nuclear matter is, in order of magnitude, 10 17 kg / m 3 and is constant for all nuclei. It greatly exceeds the density of the most dense ordinary substances.

Protons and neutrons are fermions since have spin ħ /2.

The nucleus of an atom has proper angular momentum – nucleus spin :

(9.1.2)

Where I – internal(complete)spin quantum number.

Number I takes integer or half-integer values 0, 1/2, 1, 3/2, 2, etc. Kernels with even BUT have integer spin(in units ħ ) and are subject to statistics Bose–Einstein(bosons). Kernels with odd BUT have half-integer spin(in units ħ ) and are subject to statistics Fermi–Dirac(those. nuclei - fermions).

Nuclear particles have their own magnetic moments, which determine the magnetic moment of the nucleus as a whole. The unit for measuring the magnetic moments of nuclei is nuclear magneton μ poison:

(9.1.3)

Here e – absolute value electron charge, m p Is the mass of the proton.

Nuclear magneton in m p/m e= 1836.5 times less than Bohr's magneton, it follows that the magnetic properties of atoms are determined magnetic properties his electrons .

There is a relation between the spin of the nucleus and its magnetic moment:

(9.1.4)

where γ poison - nuclear gyromagnetic ratio.

The neutron has a negative magnetic moment μ n≈ - 1.913μ poison since the direction of the neutron spin and its magnetic moment are opposite. The magnetic moment of the proton is positive and equal to μ R≈ 2.793μ poison. Its direction coincides with the direction of the proton's spin.

Distribution electric charge protons in the nucleus are generally asymmetric. A measure of the deviation of this distribution from a spherically symmetric distribution is quadrupole electric moment of the nucleus Q... If the charge density is considered the same everywhere, then Q is determined only by the shape of the nucleus. So, for an ellipsoid of revolution

(9.1.5)

Where b- the semiaxis of the ellipsoid along the spin direction, but- semiaxis in the perpendicular direction. For a nucleus elongated along the spin direction, b > but and Q> 0. For a core flattened in this direction, b < a and Q < 0. Для сферического распределения заряда в ядре b = a and Q= 0. This is true for nuclei with spin equal to 0 or ħ /2.

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The atoms of any substance are electrically neutral particles. An atom consists of a nucleus and a collection of electrons. The nucleus carries a positive charge, the total charge of which is equal to the sum of the charges of all the electrons of the atom.

General information about the nuclear charge of an atom

The charge of the atomic nucleus determines the location of the element in the periodic system of D.I. Mendeleev and, accordingly, the chemical properties of a substance consisting of these atoms and compounds of these substances. The magnitude of the charge of the nucleus is equal to:

where Z is the number of the element in the periodic table, e is the value of the electron charge or.

Elements with the same numbers Z, but different atomic masses are called isotopes. If the elements have the same Z, then their nucleus has an equal number of protons, and if the atomic masses are different, then the number of neutrons in the nuclei of these atoms is different. So, hydrogen has two isotopes: deuterium and tritium.

The nuclei of atoms have a positive charge, as they consist of protons and neutrons. A proton is a stable particle belonging to the class of hadrons, which is the nucleus of a hydrogen atom. A proton is a positively charged particle. Its charge is equal in modulus elementary charge, that is, the magnitude of the electron charge. The charge of a proton is often denoted as, then it can be written that:

The rest mass of the proton () is approximately equal to:

You can learn more about the proton by reading the section "Proton charge".

Nuclear charge measurement experiments

Moseley was the first to measure nuclear charges in 1913. The measurements were indirect. The scientist determined the relationship between the frequency of X-rays () and the charge of the nucleus Z.

where C and B are constants independent of the element for the considered series of radiation.

Chadwick measured the nuclear charge directly in 1920. He scattered particles on metal films, essentially repeating Rutherford's experiments that led Rutherford to build nuclear model atom.

In these experiments, the particles were passed through a thin metal foil. Rutherford found that in most cases the particles passed through the foil, deviating at small angles from the original direction of motion. This is due to the fact that - the particles are deflected under the influence of the electric forces of electrons, which have a much lower mass than - the particles. Sometimes, quite rarely, the particles were deflected at angles exceeding 90 o. Rutherford explained this fact by the presence in the atom of a charge that is localized in a small volume, and this charge is associated with a mass that is much greater than that of a particle.

For a mathematical description of the results of his experiments, Rutherford derived a formula that determines angular distribution- particles after their scattering by atoms. When deriving this formula, the scientist used Coulomb's law for point charges and at the same time believed that the mass of the nucleus of an atom is much greater than the mass of a particle. Rutherford's formula can be written as:

where n is the number of scattering nuclei per unit area of the foil; N is the number of particles that pass in 1 second through a unit area, perpendicular to the direction of the flow of particles; - the number of particles that are scattered inside the solid angle - the charge of the center of scattering; - mass - particles; - deflection angle - of particles; v - speed - particles.

Rutherford's formula (3) can be used to find the charge of the atomic nucleus (Z), if we compare the number of incident particles (N) with the number (dN) of particles scattered at an angle, then the function will depend only on the charge of the scattering nucleus. Carrying out experiments and applying Rutherford's formula, Chadwick found the charges of platinum, silver and copper nuclei.

Examples of problem solving

EXAMPLE 1

The task

A metal plate is irradiated with particles of high velocity. Some of these particles, upon elastic interaction with the nuclei of metal atoms, change the direction of their motion to the opposite. What is the charge of the nucleus of metal atoms (q), if the minimum distance of approach of the particle and the nucleus is equal to r. The mass of a particle is equal to its velocity v. When solving the problem, relativistic effects can be neglected. Consider the particles as pointlike, the nucleus as motionless and pointlike.

Decision

Let's make a drawing.

Moving in the direction of the atomic nucleus, the particle overcomes the Coulomb force, which repels it from the nucleus, since the particle and the nucleus have positive charges. The kinetic energy of a moving particle is converted into the potential energy of interaction between the nucleus of the metal atom and the particle. The law of conservation of energy should be taken as the basis for solving the problem:

We find the potential energy of point charged particles as:

where the charge of the particles is equal to:, since and of the particles is the nucleus of the helium atom, which consists of two protons and two neutrons, since we will assume that the experiment is carried out in air.

The kinetic energy of a particle before colliding with an atomic nucleus is equal to:

In accordance with (1.1), we equate the right-hand sides of expressions (1.2) and (1.3), we have:

From formula (1.4) we express the nuclear charge:

Answer

Instructions

In the table of DI Mendeleev, as in a multi-storey apartment building "" chemical elements, each of which occupies its own apartment. Thus, each of the elements has a specific serial number indicated in the table. The numbering of chemical elements starts from left to right, and from above. In the table, horizontal rows are called periods, and vertical columns are called groups. This is important, because by the number of the group or period, you can also characterize some parameters. atom.

An atom is chemically indivisible, but at the same time consisting of smaller component parts, which include (positively charged particles), (negatively charged) (neutral particles). The bulk atom in the nucleus (due to protons and neutrons), around which electrons revolve. In general, the atom is electrically neutral, that is, it contains the number of positive charges coincides with the number of negative ones, therefore, the number of protons is the same. Positive charge kernels atom takes place to be just due to protons.

Example No. 1. Determine the charge kernels atom carbon (C). We begin to analyze the chemical element carbon, focusing on the table of D.I. Mendeleev. Carbon is located in “apartment” No. 6. Therefore, it kernels+6 due to 6 protons (positively charged particles), which are located in the nucleus. Considering that the atom is electrically neutral, it means that there will also be 6 electrons.

Example No. 2. Determine the charge kernels atom aluminum (Al). Aluminum has a serial number - No. 13. Therefore, the charge kernels atom aluminum +13 (due to 13 protons). There will also be 13 electrons.

Example No. 3. Determine the charge kernels atom silver (Ag). Silver has a serial number - No. 47. So, the charge kernels atom silver + 47 (due to 47 protons). There are also 47 electrons.

note

In the table of D.I. Mendeleev, in one cell for each chemical element, two numerical values are indicated. Do not confuse the ordinal number and the relative atomic mass of an element.

An atom of a chemical element consists of kernels and electronic shell. The nucleus is the central part of the atom, in which almost all of its mass is concentrated. Unlike the electron shell, the nucleus has a positive charge.

You will need

Atomic number of a chemical element, Moseley's law

Instructions

In this way, charge kernels is equal to the number of protons. In turn, the number of protons in the nucleus is equal to the atomic number. For example, the atomic number of hydrogen is 1, that is, the hydrogen nucleus consists of one proton has charge+1. The atomic number of sodium is 11, charge his kernels is +11.

With alpha decay kernels its atomic number is reduced by two due to the emission of an alpha particle ( kernels atom). Thus, the number of protons in a nucleus that has undergone alpha decay is also reduced by two.
Beta decay can occur in three different ways. In the case of decay "beta-minus" neutron turns into an antineutrino when emitted. Then charge kernels per unit.
In the case of beta-plus decay, the proton converts into a neutron, positron and neutrino, charge kernels decreases by one.
In case of electronic capture charge kernels also decreases by one.

Charge kernels can also be determined from the frequency of the spectral lines of the characteristic radiation of the atom. According to Moseley's law: sqrt (v / R) = (Z-S) / n, where v is the spectral characteristic radiation, R is the Rydberg constant, S is the screening constant, n is the principal quantum number.
So Z = n * sqrt (v / r) + s.