Like a cheery sound in crystals. Atomic radius: what is the value of the effective radius of the atom to the metal

Go to food, go to modern science to be called the radius of the atom, guess what, we imagine the atom itself. Behind the classical manifestations in the center of the atom there is a nucleus, where it is stored up with protons and neutrons, and around the nucleus of the skin, in its orbit, the electronics are wrapped.

Radius of an atom in physics

Oscillations in the model of the atom of electronics є spaciously surrounded by particles, i.e., corpuscles, logically in the atomic radius (AR).

However, for the happy ones, quantum mechanical phenomena The value of the parameter cannot be as unambiguous as it would be in a classic model. Here, the electronics do not seem to be present at the sight of particles-corpuscles, but to recognize the power of power, that is, the spacious, non-interconnected objects. In such a model, it is simply uncomfortable to have an electronic position. Here, a small part is already presented in the view of the electronic orbital, the extent of which changes, in the fallowness from the point of view to the nucleus of the atom.

Otzhe, in the current model of the atom, its radius can be uniquely significant. In addition, in quantum physics, foreign chemistry, physics of solid state and other sumy sciences, the magnitude of the year begins as the radius of the sphere, in the center of which there is a core, in the middle of which is 90-98% of the energy efficiency. In fact, the origin and origin of the boundary of the atom.

I will look at the Periodic table of chemical elements (Mendeleev's table), in which atomic radii are pointed, it is possible to change the singular regularities, as it rotates in the fact that in the intervals of the period the number changes and in the upper right Such regularities are explained by the fact that in the middle of the period with the Russian evil to the right, the charge of the atom grows, that the power of the heavy electrons is increased, and with the Russian, the middle groups from the top to the bottom are more and more equal to the electronic shells.

Atomic radius in chemistry and crystalography

Yaki will see

The characteristic is given to vary greatly, in the presence of the fact that in the chemical sound of a pole is an atom. Oscillations of all the speeches in nature in the transition to their greatness are composed of molecules, understand a. R. vikoristovuyt for the designation of multi-atomic objects in molecules. And the characteristic is given to lay down the powers of entering into the molecule of atoms, that is, the state of affairs in the Periodic systems of chemical elements. Volodyuchi dear physical and cheeky authorities, Molecules make all the great changes in speech.

According to the day, the magnitude of the surrounding sphere is the power of the electrical power of the nucleus of the atom and the third electronic shells. Behind the boundaries of the center of the sphere, the power of the electric power of the earthy atom enters into action. isnu a few types of chemical linkage of atoms in molecules:

• covalent;
• ionna;
• metal;
• van der Waals.

As long as it sounds the same, it will be atomic radius.

Yak to lay in a type of chemical sound

With a covalent link AR, it starts as half of the space between the suspended atoms in a single chemical link X-X Moreover, X is a non-metal, since the deposit of power is dominant to non-metals. For example, for halogens, the covalent radius will be half of the internuclear vidstani X-X in the X2 molecule, for the selenium Se and the serky S molecules - half of the X-X in the X8 molecule, for the C win there will be half of the smallest відстані З-С in a diamond crystal.

Dana is a cheeky jingle I have the power of additivity, T.E. If the links in the molecules of the sub-link are or is inefficient, then the covalent AR changes, since the Dovzhini of multiple links is less than single ones.

With the ionic sound, it is possible to establish itself in the ionic crystals, the value of the ionic AR for the purpose of being designated as the closest anion and cation, which is to be found at the universities of the crystal lattice. This is how the visa begins to appear as a sum of radiius cikh ions.

isnu a number of ways to designate these radios When there are some differences in the value of individual ions. But as a result, the methods give approximately the same values ​​of inter-core components. Tsi methods and systems of boules are named in honor of the winners, who were carried out in the whole region during the period of presentation:

• Goldshmidt;
• Polinga;
• Bєlova and Bokogo;
• іnshikh vchenykh.

When there is a metal ring, where the wine is in the metal crystals, the AR is taken by the half of the most beautiful ones among them. The metal radius is found in the coordination number K. At K = 12th value, it is cleverly taken for one. For the coordination numbers 4, 6 and 8, the metal radii of the same element are, by and large, 0.88, 0.96 and 0.98.

If you take two different metals and parts of metal radii of elements, then the proximity of one to one value means it is necessary, but there is a lack of intelligence in the mutual difference between the metal and the type of substitution. For example, there are no small spheres before and during the years of Li, and there are no changes in the earliest minds, and there are two small balls, so that the metal radii are strongly expanding (0.236 nm and 0.155 nm are certain), and the number of nm і 0.268 nm).

Van der Waals AR vikoristovuyu for the purpose of effective development of atoms of noble gases, as well as being between the closest single atoms, so that it should be placed on different molecules and not tied with chemical bonds (butt - molecular crystals). As soon as such atoms get closer to the city, there are fewer van der Waals radii, and among them there is no stronger reason for the development. These radii are minimally permissible between the contact of two atoms, which should lie with the susceptible molecules.

In addition, the AR data is used for determining the shape of molecules, their conformations and packing in molecular crystals. Vidomy principle of "packing", if molecules that make crystal, Entering one into one with your "whistles" and "depressions". On the basis of the principle of interpreting the data of crystallography and transferring the structure of molecular crystals.

Video

Tse corrisne video will help you to see, but also the radius of the atom.

Even before that, as the power of rich electronic atoms, the bullets can be accurately insured by methods quantum mechanics, Vidomosti about їkh Budova, bully otrimanі the way of experimental vivchennya chemicheskikh spoluk, persh for all crystalline. However, the overwhelming power of the strong atoms and atoms in the crystal did not become, that it cannot be vimagati. Navpaki, during the transition of the atom from the camp in the tied all of its power, it is natural to change. The reasons are clear, for which there is also a natural perception, as well as the power of the atoms, which appear when the crystal is reached. Їх information about the nature of the chemical sound and the power of the crystal.

2.Effective radius of ATOMIV IONOV

A. Atomic Radiusi

The idea of ​​M. Laue (1912) as a result of the advancement of the future rock of the boule was given to the X-ray structural analysis of dozens of crystals, mainly minerals and metals. Mayuchi, in its own order, about a hundred values ​​of different atoms, VL Bregg was already in 1920 due to the number of individual atoms in crystals. The way of assigning radii of atoms in simple phrases, for example, in metals, is even simpler: the need to distribute the smallest number of words. Bragg extended the method to the bottom lines, estimating the radius of the cirky atom as half of the interatomic form of S-S in FeS2 pyrite (r s = 2.05 / 2 = 1.02 Å). Then it is possible to bulo virahuvati "on the lance" and radii of the other atoms (Zn s ZnS, Pro s ZnO, etc.). In total, Bregg, having made such a path of size close to 40 atoms, gave a presentation for a number of items. So, it was found that in Bragg's systems the size of electronegative atoms (rp = 0.67; ro = 0.65; r Cl = 1.05; rs = l, 02 Å) is significantly less in the case of sizes of electrically positive elements (r Na = 1.77; r Mg = l, 42; r Sr = l, 95 Å, etc.). The price entered into the control of the manifestations of Kossel's ionic model, which means that the electrons were converted from the cation and transferred to the anion, which was larger. So, in the Na + F- crystal, it is necessary to add two neon-like ions, the Na + ion with a nucleus charge of +11 is responsible for

but less than Ion F- with a nucleus charge of + 9. That is why the system of Bregg's radii appears to be universally brought about.

Before the whole idea, a lot of rock turned out because it became clear that the mechanism of establishing a chemical sound and one in all types of answers the principle of maximum recirculation electronic strength of the valence shells of Slater - Pauling. This means that it is possible to find out that the atomic radii are guilty of being close to the orbital radii of the atoms r 0, whenever and when the nucleus grows out to the maximum of the electronic strength of the valence shell. By the way, the Braggian radius of the Na atom is 1.77 Å close to the orbital radius (1.71 Å), the Al 1.35 Å radius is less expensive than the orbital one (1.31 Å), the S radius is larger than the orbital one (1.02 і 0.81 Å for example). The results of theoretical calculations r 0, as bullets finished up to 1964, as well as multidisciplinary ones, vimiryans for 1200 crystals themselves different types, J. Slater, having inspired his system of atomic radii. Smells appeared even close to Bragg's radii (average visibility becomes less than 0.03 Å).

per physical zmistїх vivedennya atomic radii and slid vikoristovuvati persh for everything in quiet vapors, since atoms are one with one covalent abo metal link.

B. Yonnі radiusi. Visnovok of the main taxonomists of the Ionian radii

Rospodil of electronic industry in simple crystals is insanely less, less in covalent ones, but it is itself, it is characterized by a change in the power of converting up to a greater degree of electrical power, but also It is logical to respect the minimum area of ​​contact with each other and try to increase the number of radii from the core to the specified minimum.

An outstanding result of X-ray structural analysis is the coordinates of atoms in crystals, i.e., Dani about multi-atom systems, which later, in the same way, is divided into parts of the surrounding regions. Three of these experimental data can be taken into account if there is less evidence about the differences in the size of atoms or about the stages of steel in the boundaries of the singing group. The vinyatk of becoming homoatomical is simple, that is, Kristaly is simple words, for those the task of assigning an atomic radius is simple (div. Poperedniy). And in

To the zealous vipad, who in their own order only by the sum of the experimental tributes from the various places, it is unwise to know the way for them to contribute to the contribution of the third ones - the third radii. For all the nobility is required to take the radius of one be-like one or any other radii in one crystal. To that, in the 1920s, if it became clear that the Bragg radio system was not satisfied with the obvious vimogues of the ionic model, there was a criterion for such a submission that the vicious actions of theoretical, or reminiscent of character, appeared.

First after the hour, the criterion, proponated by A. Lande (1920). Having let it go, in crystals with great anions and other cations, the faultless contact between the first ones is to blame, that is, E. Cations like to fix a little "bovtatisia" from the great empty ones among the anions. The price of stewing is efficiently supported by the shutters of the interstate spaces (Å), for example, in the advancing pairs of Mg and Mn with the structure of the NaCl type: MgO 2.10; MnO 2.24; Δ = 0.14; MgS 2.60; MnS 2.61; Δ = 0.01; MgSe 2.73; MnSe 2.73; Δ = 0.00. The value of Δ slid, even more for sulfide and less than for selenides Mg and Mn, is practically the same. This means that the size of anion is no longer injected into the middle period, which is monitored only when anion - anion, equal R 2. It is not important to calculate and the radius of anion is half of the current delivery, S2 is (Se2-) = 1.93 Å. This value is just enough for the purpose of introducing a further system of radio transmissions from the functioning of the interconnected systems.

In 1926, V.M. Having installed the vase, the radius O2 is 1.32 Å, and the radius F is 1.33 Å. For Goldshmidt the tsikh danikh viyavilosya to finish, to bring again the system of ionic radios, as in the coming hour it was repeatedly updated and specified. Nybilsh coated and lecture є R. Shannon's system and C. Pruitt (1970) (Dodatok 1-9).

Mayzhe one hour from Goldschmidt and right away from L. Pauling (1927) he developed the first step to the assessment of radios of the ions. Win, letting in such crystals, like Na + F-, K + Cl-, Rb + Br-, Cs + I-, are stacked from isoelectronic ions, similar to one or the same inert gas (Ne, Ar, Xe and Kr vidpovidno), radio

The cation and anion are guilty but are wrapped in proportional effective charges in the nucleus, which are repaired at the latest electronic shells.

Small. 48. Periodic abundance of atomic (1) and second (2) radii in the serial number of the element Z.

We wondered how close all the main systems of ionic radios were based on the independent minds of Goldshmidt, Polinga and Lande. In the end of the last century, in 1987, Poling zgaduvav, but, for example, in 1920 Lande knew for Ion I - the value of the radius is 2.14 Å, after three rocks of Vazasherna, having given the value of the radius yak 2.19 Å, and then through the chotiri rock Win Sam knows for a new intermediate value 2.16 Å. Tse zbig could not help but cope great feud On the next day and on the coming generation, as a result of which, within an hour, it was announced that the understanding of the "Radius Iona" will see the reality. Until now, it’s fair to say that AE Fersman’s lovesickness: “... like bi is not put to the physical zmist radiiusivs ... the stench may be great practical value both in magnitude, in terms of ease, and it is simply possible to operate in crystal chemistry, so in geochemistry. " Dyyuchi, in its own set of values ​​ordered by a set of values ​​of the order of a hundred - the number of chemical elements, it is possible to transfer approximately a lot of thousands of multinational ones, the difference is not so common. for

crystal chemistry is surrounded by a radical rank of analysis of experimental data and without the possibility of a great information.

In fig. 48 shows the periodic accumulation of atomic and ionic (CN = 6) radii in the serial number of the element. One s best typical rice Deforestation - the change in the growth of cations from the ear to the end of the skin period. Steep the fall of the growth of metals from low-valent (puddles of metal) to high-charged (N5 +, Cr6 +, etc.) Trivially smooth change in radii of lanthanum species TR3 + bulo was named by V.M. The size of ion Y3 + appears to be the same radius of No3 +, i.e.

The main meaning of the lanthanoid squeezing of the field is in the fact that the elements of the VI period appear even closer after the size to their analogs in the groups of the V period. Thus, Hf4 + is 0.02 Å more than, less Zr4 +, W6 + is 0.01 Å more than Mo6 +, Ta5 + and Nb5 + are practically of the same size. The whole process also improves the analysis of important platinum-groups (Os, Ir, Pt) with larger lungs (Ru, Rh, Pd), Au and Ag, etc. D. Win plays a great role in the isomorphism of the elementary cycles.

View respectfully rice. 48, the reader can easily remember, but in a large number of versions of the crooked radii as bi repeating the analogous movement of the crooked atomic radii, because of the change of the first downward in relation to others. Dіysno, behind the words of J. Slater (1964), I want the atomic and ionic radii to make absolutely different speeches, besides them there are not any super-phrases. Speaking "small talk", win mav on uvaz, and atomic radios - come from the nucleus to the maximum recirculation of the electronic power of the closest suspects, and the second radii, navpaki, to the least amount of sound However, unimportant on the price, offending a series of radioactive ones for the approximate value of those atomic objects in crystals of the most suitable type, since the radii of electropositive atoms are approximately 0.85 ± 0.10 more, less atoms by the same amount less, lower than іх іонні radіusi: r at. - r cat. ≈ r an. - r at. ≈ 0.85 Å. It is clear that the amount of atomic and ionic radios is for

the skin dan of the bet of the elements is guilty of but practically the same. For example, the sum of ionic radiius Na + і Сl- becomes 1.02 + 1.81 = 2.83 Å, and the sum of atomic radiius Na

i Cl: 1.80 + 1.00 = 2.80 Å.

In order to correctly register with the system of ionic radios, it is necessary to remember these basic rules.

In the first place, since it has been noted for a long time, the radius of the ion lies in the coordination number: chim is more than the CCH, tim is more than the radius of the ion. If the tables show the standard radii of the ions for the CC = 6, then for the largest CCs, you should introduce the approximate amendments: increase to the number of radials at CC> 6 and change it to the number of radii at CC< 6.

Radius іona Velmi is strongly deposited in this charge. For the cation, as the charge grows, it may change. So, for Мn2 + vin road 0.97 (CN = 6), for Мn4 + - 0.68 (CN = 6),

for Мn6 + - 0.41 (CN = 4) і Мn7 + - 0.40 Å (CN = 4).

In Dodatku 1-9 for the transition metals indicated two serii the meaning of the ionic radii is in the high- (nd) and low-spin (ns) countries. In fig. 49, a and 49, b show empirical radii of two-and trivalent Zd -elements for octahedral coordi- nation of high-spin (lower border) and high-spin (upper curve) mills.

Small. 49. Effective radii of transition elements of the IV period: a - bivalent, b - trivalent, q - number of d-electrons. Empty gurts are brought to the high-spinning camp of Iona

It is possible to bachiti, but the minimum on the lower curves fall on Fe2 + and C3 + as a matter of fact, that is, on the sixth -Electronic, which all changes in the lower orbitals. On the other side, the maxima on the upper curves fall on Mn2 + and Fe3 +, i.e.

One of the most important characteristics of chemical elements, which take part in the establishment of a chemical connection, is the size of the atom (ion): the difference between the various connections is to be determined. The size of the atom (ion) is taken from the beginning of the size of the radius or diameter. So as the atom (ion) is not clear between, then the understanding of the “atomic (ion) radius” is based on respect, but 90-98% of the electronic power of the atom (ion) is placed in the sphere radius. The knowledge of the values ​​of the atomic (ionic) radii permits the estimation of the inter-nuclei in crystals (that is, the structure of these crystals), so as for the young people who want to be among the nuclei of the atoms (the latter are so close) not vikonutsya at all vypadkah.

pid atomic radiuscheery element(About the ionic radio div. Nizche), which took part in the establishment of a chemical sound, half of the equally important internuclear space between the nearest atoms in the crystalline solution of the element was taken into account. The tse of the understander, the velma is simple, as if to look at the atoms (іoni) in the eyes of the rough sacks, in fact, it appears foldable and often not unambiguous. The atomic (ionic) radius of a chemical element is not of a constant value, but varies in fallowness among a number of factors that have chosen the type of chemical element

and coordination number.

I will create one and the same atom (ion) in small crystals різні tipi a chemical link, then a new radius will be covalent in a crystal with a covalent link; ionic in crystal with an ionic ring; metal in metal; van der Waals in a molecular crystal. Injection to the type of chemical compound can be quilted on such a butt. Diamonds have all the chemical bonds that are covalent and approved sp 3-hybrids, because all the suspension of a given atom is located on one and

the same from the same ( d= 1.54 AA) і covalent radius in carbon in diamond

doorway 0.77 A˚. In the crystal, the mish'yaku appears between atoms tied by covalent links ( d 1 = 2.52 AA), significantly less, less than atoms bound by van der Waals forces ( d 2 = 3.12 AA), so As will have a covalent radius, equal to 1.26 AA, and van der Waals, which will be 1.56 AA.

The atomic (ionic) radius changes even more rapidly when the coordination number changes (it can be helpful in case of polymorphic transformations of elements). The less is the coordination number, the less the steps are occupied by the atoms (ions) and the less internuclear space. The increase in the coordination number depends on the increase in the number of inter-core stations.

From the said vipliv, what atomic (ionnі) radiiusi new elements To take part in the establishment of a chemical connection, it is possible to change only todly, if the smell is created by crystals, in which one and the same type of chemical connection is realized, and in a number of elements in the number of coordinators of the same crystals.

The main features of the atomic and ionic radios are discernible in a larger report.

pid covalent radii of elements half of the equally important internuclear form is taken up by the closest atoms, with a covalent link.

The specialty of covalent radii and їx steel in the old "covalent structures" with the same coordination number Z Since, in addition, covalent radii, as a rule, are additively linked one to one, so that A-B appears as one of the A-A and B-B stations when covalent links and the same coordination numbers are present in all the same structures.

Razr_znyayut normal, tetrahedral, octahedral, quadratic and linear covalent radii.

The normal covalent radius of an atom will appear to fall, if the atom is in the form of covalent bonds, it will appear in the periodic table: for carbon - 2, for nitrogen - 3 times the normal range. order) sound (single sound, sub-link, pot). If the bells are set up when they cross the hybrid electronic ones, then talk about the tetrahedral

(Z k = 4, sp 3-hybrid orbital), octahedral ( Z k = 6, d 2sp 3-hybrid orbital), quadratic ( Z k = 4, dsp 2-hybrid orbital), line ( Z k = 2, sp- hybrid orbital) covalent radii.

About the covalent radii of the nobility nasty (the meaning of the values ​​of covalent radii for a number of elements of guidance).

1. Covalent radii, on the view of them, cannot be interpreted as radii of atoms, but a spherical shape. The covalent radii become stagnant only for the enumeration of internuclear objects between atoms, shared by covalent links, and there is nothing to suggest about the presence of atoms of the same type as not covalently bound.

2. The value of the covalent radius is the multiplicity of the covalent link. The connection is shorter than the sub-link, which is shorter than the single one, so the covalent radius of the sub-link is less than the covalent radius of the sub-link, which is less

single. Slid mother on uvaz, but the order of the multiplicity of the sound is not necessarily guilty of but a whole number. We can use a shot, if the ring is resonant (benzene molecule, Mg2 Sn, div. Nizche). In general, the covalent radius can be intertwined with the meanings, which are in the same order of magnitude.

3. Ikscho ligaments have a change of covalent-ionic character, ale z high step covalent warehouse link, then it is possible to introduce an understanding of the covalent radius, or it is impossible not to pour in the ion warehouse link by its value. In some cases, the infusion can lead to a significant decrease in the covalent radius, up to 0.1 AA. It's a pity, try to transfer the value of the whole effect in the

In the fall did not end with success.

4. The value of the covalent radius lies in the type of hybrid orbitals, which take part in the established covalent link.

іонні radіusi Naturally, there can be no value as half the sum of the nuclei of the most common ions, so as, as a rule, the size of the cations and the ones grows rapidly. In addition, the symmetry of the ions can often be seen as spherical. Protect for real іonny crystals під Ionny Radius It was accepted by the reason of the radius coul, which is approximated by the ion.

Інні radіusi vikoristovuyutsya for close estimates of internuclear sites in іonnyh crystals. At the same time, you will be able to find the most suitable cations and anion for the most part of the radio. The typical value of the value of internuclear views through ionic radii in such crystals becomes ≈0.01 A˚.

There is a small number of systems of ionic radios, which are based on the values ​​of ionic radios of individual ions, but to produce up to approximately the same inter-core stations. The first of the robot for the designation of the first radii was carried out by V.M. Goldshmit in the 20s of the 20th century. At them the author vikoristovav, from one side, the internuclear views in the ionic crystals, vimiryana methods of X-ray structural analysis, and, from the side, - the value of the ionic radii in F- and O2-, singing

by refractometry. Most of these systems also spiral on the basis of diffraction methods, internuclear forms in crystals and on the basis of the "reference" value of the ionic radius of a particular ion. Most widely distributed systems

Poling of cym reference values ​​є ionic radius peroxide-ion O2-, pivniy

1.40 A˚. The Q value for O2 is good to use the theoretical dimensions. In the systems of G.B. Boky and N.V. Bulov, as one of the most overpriced ones, the O2 radius is accepted as equal to 1.36 A˚.

In the 70s and 80s, the rocks of the boules zroblenі sprobi direct value Radius on the path of electronic intelligence by methods of X-ray structural analysis for the mind, that the minimum of electronic competence on the line, from the bottom of the core, to take over the cordon of ions. It has been shown that it is a straightforward method to produce up to the enviable values ​​of the ionic radii of the cations and to the underestimation of the values ​​of the radii of the anniversaries. In addition, the meaning of these radii, singing in a direct way, cannot be transferred from one experience to the other, and the view from the additivity is great. To that such іonnі radіusi, do not be vicious for the transfer of inter-core countries.

About іonny radіusіv of the nobility nasten (in the tables, pointing below, the data on the magnitude of the іonny radіusіv according to Bokiy i Bulov).

1. Ionny radius for one and the same element change in depletion from one charge, and for one and the same Ion to lay down from a coordination number. Reciprocally from the coordination number, the tetrahedral and octahedral radii are developed.

2. In the middle of one vertical row, more precisely in the middle of one group, periodically

The system of radii of ions with the same charge grows from the increase of the atomic number of the element, the fragments of the increase in the number of shells occupied by the electrons, and hence the size of the ion.

Radius, A˚

3. For positively charging ions of atoms in one period, the ions quickly change due to the increased charge. Shvidke change will explain two main officials in one direction: the heavier "own" electrical cations, the charge of which increases from the increase in the atomic number; increase the strength of the interaction between the cation and the power supply of the cation for the increased charge of the cation.

Radius, A˚

4. For negatively charged ions of atoms in one period, ions of atoms will increase from the increase of negative charge. Two factors, about yaki yshla mova in in front of the item In general, there is a trend in the opposite side, moreover, it is the first factor (the increase in the negative charge of anion supervising the growth of the ionic radius), which increases the increase in the negative charge in the increase of the negative

Radius, A˚

5. For one and the same element, that is, with the same electronic configuration, the radius of the cation is less than that of the anion. The price is explained by the changes in the burden of additional "additional" electrons to the nucleus of the anion and the improvement in the efficiency of the return of internal electrons (the cation has fewer elec- trons).

Radius, A˚

6. Measurements of ions with the same charge follow the periodicity of Mendelian tables. However, the value of the ionic radius is not proportional to the charge of the nucleus Z It is surrounded by a strong core of electronics. In addition, the inclusion of periodic depletion represents lanthanum and actinoids, in the ranks of which radii of atoms and ions with the same charge do not grow, but change with the growth of the atomic number (so called lanthanum data).

11 internal dі f- columns with the head quantum number less, less than the quantum number given to the period. At the same time, there are quantum mechanics in d and especially in f the elektron stanakh is located closer to the core, lower in sі p countries given to the period with a great quantum number, that dі f-Electronically located in the inner regions of the atom, if you want to store the number of stations with electrons (see the article about the electronic equipments in the energy space), go to the bottom.

metal radio Vvazhayutsya half of the most beautiful in the nuclei of atoms in the crystallization of the structure of the element-metal. The stench lies in the coordination number. How to accept the metal radius of a certain element when Z k = 12 per unit, then at Z k = 8, 6 and 4 metal radii, and the same element will be approximately equal to 0.98; 0.96; 0.88. Metal radii may be the power of additivity. The knowledge of these values ​​allows an approximate forecast of the parameters of crystal lattices of intermetallic spheres.

For atomic radii of metals, characteristic features are characteristic (data on the magnitude of atomic radii of metals can be found in).

1. Metallic atomic radii of transition metals, as a rule, less than metallic radii of non-transient metals, which indicates a great performance in the metals of transitional elements. The particularity of the team was amazed by the fact that they were thinking about the transitional groups and the closest to them in the periodic systems. d-columns, and electronics in d-stay be brothers to the fate of the approved chemical sound. The change in connection can be tied partly with the appearance of a covalent warehouse connection and partly with van der Waals interconnected by the modularity of the monarchs. Crystals have gold and tungsten, for example, electronics in d-stan to make a hundred of additions to the energy connection.

2. In the boundaries of one vertical group in the world of letting down from top to bottom atomic radii of metals grow, which is explained by the last increase in the number of elec- trons (the increase in the number of shells occupied by elec- trons).

3. In the intervals of one period, more precisely, they can be repaired from tin metal to the middle of the group of transition metals, in the right direction the atomic metal radii change. At the same end of life, the electrical charge of the atomic nucleus and the increase in the number of electrons, which is located on the valence band, will increase. With an increase in the number of electrons ringing, so that they fall on one atom, the metal ringing changes, and at the same time, through the increased charge of the nucleus, the heavy cores (internal) electrons in the nucleus will be able to increase, thus the value of the metal atomic radiation will change.

4. Transition metals of the VII and VIII groups in the same period in the first next month may be of the same metal radii. Mabut, if mova ide about the elements, maybe 5 and a larger number d-electrons, increasing the charge of the nucleus and connecting with the cycle of the efficiency of the backbone of the electrons, leading to a change in the atomic metal radius, compensating for the effects, noises, and increasing the number of electrons in the atom (last) until the increase in the metal radius (the number of stations occupied by the electrons grows).

5. Increased radios (div. P. 2) in the transitional elements, as well as during the transition from the fourth to the fifth period, do not appear in the transitional elements when

transitions from the last to the last period; Metallic atomic radii and common (vertically aligned) elements in the same two remaining periods may be the same. Mabut, tse tied with tim, but at the elements that are roasted between them, get a little bit f- Columns, which increase the charge of the nucleus and are tied with a large number of efficiencies, appear more and more, less efficiently, tied with a growth-resistant number of electrons (lanthanum crimping).

Element of the 4th period

Radius, A˚

Element s 5 period

Radius, A˚

Element s 6 period

Radius, A˚

6. Call the metal radii more, less radii, however, it is not significant to refer to the covalent radii of the quiet elements, I would like all without a blame to be more covalent. There is a great difference in the values ​​of metal atomic and ionic radios in some and quiet elements. However, the difference in the values ​​of the metal and covalent radii of some and the same elements can be explained as less of a difference in the magnitude of the metallic and covalent bonds.

pid van der Waalswich radius Reason is taken half of the equally important internuclear form between the closest atoms, which van der Waals calls. Van der Waals radii visually start the effective measurement of atoms in noble gases. In addition, as a matter of value, van der Waals 'atomic radius can fill half of the internuclear substance between the closest single atoms bound by van der Waals' bonds and overlap with different molecules (for example, crystals). When the atoms are closer to the stand, there are fewer van der Waals radios, the winners are stronger than the number of atoms. To this, the van der Waals atomic radii characterize the minimally permissible contact of atoms, which should lie with other molecules. Data about the magnitude of van der Waals atomic radii for certain atoms can be found in).

The knowledge of van der Waals' atomic radii allows for the formation of the form of molecules, their packaging in molecular crystals. Van der Waals radii are more than all overwhelmed by the radii of the same elements, as explained by the weakness of vander Waals forces.

From the effective radius of the atom, or the ion, the radius of the sphere of the yogi develops, and the atom (ion) is impacted by an unstable cooler. Vikoristovuchi planetary model of the atom, it represents the nucleus, which is wrapped around the orbitals of the electronic. The last of the elements in the periodic system Mendelian shows the last of the storage of electronic shells. The effective radius of the ion lies in the storage of electronic shells, but it is not suitable for the radio of the external orbit. For the purpose of establishing an effective radius, the formation of atoms (s) in the structure of the crystal is similar to that of a similar amount, so that it becomes the center of the city. Atomic and ionic radii of values ​​experimentally based on X-ray measurements of inter-nuclear systems and theoretically calculated on the basis of quantum-mechanical phenomena.

Allowance for new radii to comply with the onset of laws:

1. Middle of one vertical row periodic systems The radii of ions with the same charge increase with the growth of the atomic number, and the increase in the increase in the number of electronic shells, and hence, the size of the atom.

2. For one and the same element, the ionic radius grows from the increase of the negative charge and decreases from the increase of the positive charge. The radius of the anion is greater than the radius of the cation, the fragments of the anion are an excess of electrons, and that of the cation is not enough. For example, for Fe, Fe 2+, Fe 3+ the effective radius of the road is 0, 126, 0, 080 and 0, 067 nm, for example, for Si 4, Si, Si 4+ the effective radius of the road is 0, 198, 0, 118 and 0 , 040 nm.

3. The analysis of atoms and ions follows the periodicity of the Mendelian system; vklyuchennya warehouse items from No. 57 (lanthanum) to No. 71 (lutetium), de radiusi atoms do not change, but rather change (so called lanthanum depressions), and items from No. 89 (actin_y) and distant

The atomic radius of a chemical element lies at the coordination number. The increase in the coordination number depends on the number of supervisors. With a large difference in the value of atomic radii, which show two different coordination numbers, do not lie in the type of chemical ring (for reason, the type of connection in structures with the same coordination numbers). The change of atomic radii due to the change in the coordination number is literally recognized on the values ​​of the common changes in the case of polymorphic transformations. For example, in case of a cold shape, when it is converted from a modification from a face-centered cubic grates into a modification from a volume-centered cubic grates, a small amount at 906 ° C, a maximum of 9% should be increased in total. The price is tied with that, for a change in the coordination number from 12 to 8 atomic radius changes by 3%. So, the change of atomic radii in the case of polymorphic transformations in the meaning of the world will compensate for those changes that are guilty of the bullets, as if the atomic radii did not change. Atomic radii of elements can be set only with the same coordination number.

Atomic (ion) radii lie also as a type of chemical sound.

Crystals with a metallic ring have an atomic radius as half of the atoms in the range of the nearest atoms. In the case of solid solutions, metal and atomic radii change by a folding rank.

From the covalent radii of the elements with the covalent link, there is half the interatomic appearance between the closest atoms, which are separated by a single covalent link. The specialty of covalent radii є їх steel in the young covalent structures with the same coordination numbers. So, in single links C-C in diamonds and saturated in carbohydrates of the same value and equal to 0.154 nm.

Ionny radii in speech with an ionic sound cannot be equal to half the sum of the values ​​between the nearest ions. As a rule, the size of cations and anion is quickly developed. In addition, the symmetry of the ions grows as spherical. It’s as early as possible to estimate the magnitude of the radios. At the beginning of the show, we estimate the number of radio elements, and then, from the experimentally significant ones, we start with the new radio frequency elements.

Van der Waals radii visually start the effective measurement of atoms in noble gases. In addition, van der Waals atomic radii invade half of the internuclear space between the closest identical atoms, not tied together with a chemical ring, so as to overlap with different molecules (for example, crystals).

In case of viciousness in rosrahunka and prompts of the values ​​of the atomic (ionic) radii, the values ​​are followed by the brothers from the tables, prompted by the same system.