Periodic table of elements. Periodic law D

Option 1

A1. What is the physical meaning of the group number of D.I. Mendeleev’s table?

2.This is the charge of the nucleus of an atom

4.This is the number of neutrons in the nucleus

A2. What is the number of energy levels?

1. Serial number

2. Period number

3. Group number

4. Number of electrons

A3.

2. This is the number of energy levels in an atom

3. This is the number of electrons in an atom

A4. Indicate the number of electrons in the outer energy level in the phosphorus atom:

1. 7 electrons

2. 5 electrons

3. 2 electrons

4. 3 electrons

A5. In which row are the formulas of hydrides located?

1. H 2 O, CO, C 2 H 2 , LiH

2.NaH, CH 4 , H 2 O, CaH 2

3. H 2 O,C 2 H 2 , LiH, Li 2 O

4. NO, N 2 O 3 , N 2 O 5 , N 2 O

A 6. In which compound is the oxidation state of nitrogen equal to +1?

1. N 2 O 3

2. NO

3. N 2 O 5

4. N 2 O

A7. Which compound corresponds to manganese (II) oxide:

1. MnO 2

2. Mn 2 O 7

3. MnCl 2

4. MnO

A8. Which row contains only simple substances?

1. Oxygen and ozone

2. Sulfur and water

3. Carbon and bronze

4. Sugar and salt

A9. Identify an element if its atom has 44 electrons:

1. cobalt

2. tin

3. ruthenium

4. niobium

A10. What has an atomic crystal lattice?

1. iodine

2. germanium

3. ozone

4. white phosphorus

IN 1. Match

Number of electrons in the outer energy level of an atom

Chemical element symbol

A. 3

B. 1

AT 6

G. 4

1) S 6) C

2) Fr 7) He

3) Mg 8) Ga

4) Al 9) Te

5) Si 10) K

AT 2. Match

Substance name

Substance formula

A. Oxidesulfur(VI)

B. Sodium hydride

B. Sodium hydroxide

G. Iron(II) chloride

1)SO 2

2) FeCl 2

3) FeCl 3

4) NaH

5) SO 3

6) NaOH

Option 2

A1. What is the physical meaning of the period number of D.I. Mendeleev’s table?

1.This is the number of energy levels in an atom

2.This is the charge of the nucleus of an atom

3. This is the number of electrons in the outer energy level of an atom

4.This is the number of neutrons in the nucleus

A2. What is the number of electrons in an atom?

1. Serial number

2. Period number

3. Group number

4. Number of neutrons

A3. What is the physical meaning of the atomic number of a chemical element?

1. This is the number of neutrons in the nucleus

2. This is the charge of the atomic nucleus

3. This is the number of energy levels in an atom

4. This is the number of electrons in the outer energy level of an atom

A4. Indicate the number of electrons in the outer energy level in a silicon atom:

1. 14 electrons

2. 4 electrons

3. 2 electrons

4. 3 electrons

A5. In what row are the oxide formulas located?

1. H 2 O, CO, CABOUT 2 , LiABOUTH

2.NaH, CH 4 , H 2 O, CaH 2

3. H 2 O,C 2 H 2 , LiH, Li 2 O

4. NO, N 2 O 3 , N 2 O 5 , N 2 O

A 6. In which compound does the oxidation state of chlorine equal to -1?

1. Cl 2 O 7

2. HClO

3. HCl

4. Cl 2 O 3

A7. Which compound corresponds to nitric oxide (III):

1. N 2 O

2. N 2 O 3

3. NO

4. H 3 N

A8. In which row are simple and complex substances located?

1. Diamond and ozone

2. Gold and carbon dioxide

3. Water and sulfuric acid

4. Sugar and salt

A9. Identify an element if its atom has 56 protons:

1. iron

2. tin

3. barium

4. manganese

A10. What has a molecular crystal lattice?

diamond

silicon

rhinestone

boron

IN 1. Match

Number of energy levels in an atom

Chemical element symbol

A. 5

B. 7

IN. 3

G. 2

1) S 6) C

2) Fr 7) He

3) Mg 8) Ga

4) B 9) Te

5) Sn 10) Rf

AT 2. Match

Substance name

Substance formula

A. Carbon hydride (IV)

B. Calcium oxide

B. Calcium nitride

G. Calcium hydroxide

1) H 3 N

2) Ca(OH) 2

3) KOH

4) CaO

5)CH 4

6) Ca 3 N 2

IV - VII - long periods, because consist of two rows (even and odd) of elements.

Typical metals are located in even rows of large periods. The odd series begins with a metal, then the metallic properties weaken and non-metallic properties increase, and the period ends with an inert gas.

Group- this is a vertical row of chemicals. elements combined by chemical properties.

Group

main subgroup secondary subgroup

The main subgroup includes the secondary subgroup includes

elements of both small and large; elements of only large periods.

periods.

H, Li, Na, K, Rb, Cs, Fr Cu, Ag, Au

small large large

The following patterns are characteristic of elements combined into the same group:

1. Higher valency of elements in compounds with oxygen(with some exceptions) corresponds to the group number.

Elements of secondary subgroups may also exhibit other higher valences. For example, Cu - an element of group I of the side subgroup - forms the oxide Cu 2 O. However, the most common are compounds of divalent copper.

2. In the main subgroups(top down) With an increase in atomic masses, the metallic properties of elements increase and the non-metallic ones weaken.

The structure of the atom.

For a long time, the prevailing opinion in science was that atoms are indivisible, i.e. do not contain simpler components.

However, at the end of the 19th century, a number of facts were established that testified to the complex composition of atoms and the possibility of their interconversions.

Atoms are complex formations built from smaller structural units.

core

p+ - proton

atom

n 0 - neutron

ē - electron - outside the nucleus

For chemistry, the structure of the electron shell of an atom is of great interest. Under electron shell understand the totality of all the electrons in an atom. The number of electrons in an atom is equal to the number of protons, i.e. the atomic number of the element, since the atom is electrically neutral.

The most important characteristic of an electron is the energy of its connection with an atom. Electrons with similar energy values form a single electron layer.

Each chem. the element in the periodic table was numbered.

The number that each element receives is called serial number.

Physical meaning of the serial number:

1. What is the atomic number of the element, so is the charge of the atomic nucleus.

2. The same number of electrons revolve around the nucleus.

Z = p + Z - element serial number

n 0 = A - Z

n 0 = A - p + A - atomic mass of the element

n 0 = A - ē

For example, Li.

Physical meaning of the period number.

What period an element is in, how many electron shells (layers) it will have.

Not +2

Li +3 Be +4 V +5 N +7

Determination of the maximum number of electrons in one electron shell.

Having studied the properties of elements arranged in a series of increasing values of their atomic masses, the great Russian scientist D.I. Mendeleev in 1869 derived the law of periodicity:

the properties of the elements, and therefore the properties of the simple and complex bodies they form, are periodically dependent on the magnitude of the atomic weights of the elements.

modern formulation of Mendeleev's periodic law:

The properties of chemical elements, as well as the forms and properties of compounds of elements, periodically depend on the charge of their nuclei.

The number of protons in the nucleus determines the magnitude of the positive charge of the nucleus and, accordingly, the atomic number Z of the element in the periodic table. The total number of protons and neutrons is called mass number A, it is approximately equal to the mass of the nucleus. Therefore the number of neutrons (N) in the core can be found by the formula:

N = A - Z.

Electronic configuration- formula for the arrangement of electrons in different electron shells of an atomic-chemical element

Or molecules.

17. Quantum numbers and the order of filling energy levels and orbitals in atoms. Klechkovsky's rules

The order of electron distribution among energy levels and sublevels in the shell of an atom is called its electronic configuration. The state of each electron in an atom is determined by four quantum numbers:

1. Principal quantum number n characterizes to the greatest extent the energy of an electron in an atom. n = 1, 2, 3….. The electron has the lowest energy at n = 1, while it is closest to the nucleus of the atom.

2. Orbital (side, azimuthal) quantum number l determines the shape of the electron cloud and, to a small extent, its energy. For each value of the principal quantum number n, the orbital quantum number can take zero and a number of integer values: l = 0…(n-1)

Electron states characterized by different values of l are usually called energy sublevels of the electron in the atom. Each sublevel is designated by a specific letter and corresponds to a specific shape of the electron cloud (orbital).

3. Magnetic quantum number m l determines possible orientations of the electron cloud in space. The number of such orientations is determined by the number of values that the magnetic quantum number can take:

m l = -l, …0,…+l

The number of such values for a specific l: 2l+1

Respectively: for s-electrons: 2·0 +1=1 (a spherical orbital can be oriented in only one way);

4. Spin quantum number m s о reflects the presence of the electron's own momentum.

The spin quantum number can have only two values: m s = +1/2 or –1/2

Distribution of electrons in multielectron atoms occurs in accordance with three principles:

Pauli principle

An atom cannot have electrons that have the same set of all four quantum numbers.

2. Hund's rule(tram rule)

In the most stable state of the atom, electrons are located within the electron sublevel so that their total spin is maximum. Similar to the order of filling double seats in an empty tram that comes to a stop - first, people who are unfamiliar with each other are seated on double seats (and electrons in orbitals) one by one, and only when the empty double seats are finished in two.

The principle of minimum energy (Rules of V.M. Klechkovsky, 1954)

1) As the charge of the atomic nucleus increases, the sequential filling of electronic orbitals occurs from orbitals with a smaller value of the sum of the principal and orbital fifth numbers (n + l) to orbitals with a larger value of this sum.

2) For the same values of the sum (n + l), the filling of the orbitals occurs sequentially in the direction of increasing the value of the principal quantum number.

18. Methods for modeling chemical bonds: valence bond method and molecular orbital method.

Valence bond method

The simplest is the valence bond (VB) method, proposed in 1916 by the American physical chemist Lewis.

The valence bond method considers a chemical bond as the result of the attraction of the nuclei of two atoms to one or more electron pairs they share. Such a two-electron and two-center bond, localized between two atoms, is called covalent.

In principle, two mechanisms for the formation of a covalent bond are possible:

1. Pairing of electrons of two atoms under the condition of opposite orientation of their spins;

2. Donor-acceptor interaction, in which a ready electron pair of one of the atoms (donor) becomes common in the presence of an energetically favorable free orbital of another atom (acceptor).

1. Indicate the name of the element and its designation. Determine the element's serial number, period number, group, subgroup. Indicate the physical meaning of the system parameters - serial number, period number, group number. Justify the position in the subgroup.

2. Indicate the number of electrons, protons and neutrons in an atom of the element, the charge of the nucleus, and the mass number.

3. Compose the complete electronic formula of the element, determine the electronic family, classify the simple substance as a metal or non-metal.

4. Graphically depict the electronic structure of the element (or the last two levels).

5. Graphically represent all possible valence states.

6. State the number and type of valence electrons.

7. List all possible valencies and oxidation states.

8. Write the formulas of oxides and hydroxides for all valence states. Indicate their chemical nature (support your answer with the equations of the corresponding reactions).

9. Give the formula of a hydrogen compound.

10. Name the scope of application of this element

Solution. In PSE, the element with serial number 21 corresponds to scandium.

1. The element is in the IV period. The period number means the number of energy levels in the atom of this element; it has 4. Scandium is located in the 3rd group - on the outer level of the 3rd electron; in a side subgroup. Consequently, its valence electrons are located in the 4s and 3d sublevels. The atomic number numerically coincides with the charge of the atomic nucleus.

2. The charge of the scandium atom nucleus is +21.

The number of protons and electrons is 21 each.

Number of neutrons A–Z = 45 – 21 = 24.

General composition of the atom: ( ).

3. Full electronic formula of scandium:

1s 2 2s 2 2p 6 3s 2 3p 6 3d 1 4s 2 .

Electronic family: d-element, as in the filling stage
d-orbitals. The electronic structure of the atom ends with s-electrons, so scandium exhibits metallic properties; a simple substance is metal.

4. Electronic graphic configuration looks like:

5. Possible valence states determined by the number of unpaired electrons:

- in basic condition:

– in scandium in an excited state, an electron from the 4s orbital will move to a free 4p orbital, one unpaired d-electron increases the valence capabilities of scandium.

Sc has three valence electrons in its excited state.

6. Possible valencies in this case are determined by the number of unpaired electrons: 1, 2, 3 (or I, II, III). Possible oxidation states (reflect the number of displaced electrons) +1, +2, +3 (since scandium is a metal).

7. The most characteristic and stable valence is III, oxidation state +3. The presence of only one electron in the d-state causes low stability of the 3d 1 4s 2 configuration.

Scandium and its analogs, unlike other d-elements, exhibit a constant oxidation state of +3, this is the highest oxidation state and corresponds to the group number.

8. Formulas of oxides and their chemical nature:

higher oxide form – (amphoteric);

hydroxide formulas: – amphoteric.

Reaction equations confirming the amphoteric nature of oxides and hydroxides:

(lithium scandate),

(scandium chloride),

( Potassium hexahydroxocandiate(III) ),

(scandium sulfate).

9. It does not form a compound with hydrogen, since it is in a side subgroup and is a d-element.

10. Scandium compounds are used in semiconductor technology.

Example 2. Which of the two elements, manganese or bromine, has stronger metallic properties?

Solution. These elements are in the fourth period. Let's write down their electronic formulas:

Manganese is a d-element, i.e. an element of a side subgroup, and bromine is
p-element of the main subgroup of the same group. At the outer electronic level, the manganese atom has only two electrons, while the bromine atom has seven. The radius of a manganese atom is less than the radius of a bromine atom with the same number of electron shells.

A common pattern for all groups containing p- and d-elements is the predominance of metallic properties in d-elements.
Thus, manganese has more pronounced metallic properties than bromine.

From your first chemistry lessons you used D.I. Mendeleev’s table. It clearly demonstrates that all the chemical elements that form the substances of the world around us are interconnected and obey general laws, that is, they represent a single whole - a system of chemical elements. Therefore, in modern science, D.I. Mendeleev’s table is called the Periodic Table of Chemical Elements.

Why “periodic” is also clear to you, since the general patterns in changes in the properties of atoms, simple and complex substances formed by chemical elements are repeated in this system at certain intervals - periods. Some of these patterns shown in Table 1 are already known to you.

Thus, all chemical elements existing in the world are subject to a single, objectively valid Periodic Law in nature, the graphic representation of which is the Periodic Table of Elements. This law and system are named after the great Russian chemist D.I. Mendeleev.

D.I. Mendeleev came to the discovery of the Periodic Law by comparing the properties and relative atomic masses of chemical elements. To do this, D.I. Mendeleev wrote down on a card for each chemical element: the symbol of the element, the value of the relative atomic mass (at the time of D.I. Mendeleev this value was called atomic weight), the formulas and nature of the higher oxide and hydroxide. He arranged 63 chemical elements known by that time into one chain in increasing order of their relative atomic masses (Fig. 1) and analyzed this set of elements, trying to find certain patterns in it. As a result of intense creative work, he discovered that there are intervals in this chain - periods in which the properties of the elements and the substances formed by them change in a similar way (Fig. 2).

Rice. 1.
Cards of elements arranged in increasing order of their relative atomic masses

Rice. 2.
Cards of elements arranged in order of periodic changes in the properties of elements and substances formed by them

Laboratory experiment No. 2
Modeling the construction of the Periodic Table of D. I. Mendeleev

Model the construction of the Periodic Table of D.I. Mendeleev. To do this, prepare 20 cards measuring 6 x 10 cm for elements with serial numbers from 1st to 20th. On each card, indicate the following information about the element: chemical symbol, name, relative atomic mass, formula of higher oxide, hydroxide (indicate their nature in parentheses - basic, acidic or amphoteric), formula of volatile hydrogen compound (for non-metals).

Shuffle the cards and then arrange them in a row in order of increasing relative atomic masses of the elements. Place similar elements from 1st to 18th under each other: hydrogen above lithium and potassium under sodium, respectively, calcium under magnesium, helium under neon. Formulate the pattern you have identified in the form of a law. Note the discrepancy between the relative atomic masses of argon and potassium and their location in terms of the common properties of the elements. Explain the reason for this phenomenon.

Let us list once again, using modern terms, the regular changes in properties that manifest themselves within periods:

metallic properties weaken;
non-metallic properties are enhanced;
the degree of oxidation of elements in higher oxides increases from +1 to +8;
the oxidation degree of elements in volatile hydrogen compounds increases from -4 to -1;
oxides from basic through amphoteric are replaced by acidic ones;
hydroxides from alkalis through amphoteric hydroxides are replaced by oxygen-containing acids.

Based on these observations, D.I. Mendeleev made a conclusion in 1869 - he formulated the Periodic Law, which, using modern terms, sounds like this:

Systematizing chemical elements based on their relative atomic masses, D. I. Mendeleev also paid great attention to the properties of the elements and the substances formed by them, distributing elements with similar properties into vertical columns - groups. Sometimes, in violation of the pattern he had identified, he placed heavier elements in front of elements with lower relative atomic masses. For example, he wrote cobalt in his table before nickel, tellurium before iodine, and when inert (noble) gases were discovered, argon before potassium. D.I. Mendeleev considered this order of arrangement necessary because otherwise these elements would fall into groups of elements dissimilar to them in properties. So, in particular, the alkali metal potassium would fall into the group of inert gases, and the inert gas argon would fall into the group of alkali metals.

D.I. Mendeleev could not explain these exceptions to the general rule, as well as the reason for the periodicity in changes in the properties of elements and the substances formed by them. However, he foresaw that this reason lay in the complex structure of the atom. It was the scientific intuition of D.I. Mendeleev that allowed him to construct a system of chemical elements not in the order of increasing their relative atomic masses, but in the order of increasing charges of their atomic nuclei. The fact that the properties of elements are determined precisely by the charges of their atomic nuclei is eloquently demonstrated by the existence of isotopes that you met last year (remember what they are, give examples of isotopes known to you).

In accordance with modern ideas about the structure of the atom, the basis for the classification of chemical elements is the charges of their atomic nuclei, and the modern formulation of the Periodic Law is as follows:

The periodicity in changes in the properties of elements and their compounds is explained by the periodic repetition in the structure of the external energy levels of their atoms. It is the number of energy levels, the total number of electrons located on them and the number of electrons at the outer level that reflect the symbolism adopted in the Periodic System, that is, they reveal the physical meaning of the element’s serial number, period number and group number (what does it consist of?).

The structure of the atom makes it possible to explain the reasons for changes in the metallic and non-metallic properties of elements in periods and groups.

Consequently, the Periodic Law and the Periodic System of D.I. Mendeleev summarize information about chemical elements and the substances formed by them and explain the periodicity in changes in their properties and the reason for the similarity of the properties of elements of the same group.

These two most important meanings of the Periodic Law and the Periodic System of D.I. Mendeleev are complemented by one more, which is the ability to predict, i.e. predict, describe properties and indicate ways of discovering new chemical elements. Already at the stage of creating the Periodic Table, D.I. Mendeleev made a number of predictions about the properties of elements not yet known at that time and indicated the ways of their discovery. In the table he created, D.I. Mendeleev left empty cells for these elements (Fig. 3).

Rice. 3.
Periodic table of elements proposed by D. I. Mendeleev

Vivid examples of the predictive power of the Periodic Law were the subsequent discoveries of elements: in 1875, the Frenchman Lecoq de Boisbaudran discovered gallium, predicted by D. I. Mendeleev five years earlier as an element called “ekaaluminum” (eka - next); in 1879, the Swede L. Nilsson discovered the “ekabor” according to D. I. Mendeleev; in 1886 by the German K. Winkler - “exasilicon” according to D. I. Mendeleev (determine the modern names of these elements from D. I. Mendeleev’s table). How accurate D.I. Mendeleev was in his predictions is illustrated by the data in Table 2.

table 2
Predicted and experimentally discovered properties of germanium

Predicted by D.I. Mendeleev in 1871	Established by K. Winkler in 1886
Relative atomic mass is close to 72	Relative atomic mass 72.6
Gray refractory metal	Gray refractory metal
Metal density is about 5.5 g/cm 3	Metal density 5.35 g/cm 3
Oxide formula E0 2	Ge0 2 oxide formula
Oxide density is about 4.7 g/cm3	Oxide density 4.7 g/cm3
The oxide will be reduced to metal quite easily	Ge0 2 oxide is reduced to metal when heated in a hydrogen stream
Chloride ES1 4 should be a liquid with a boiling point of about 90 °C and a density of about 1.9 g/cm3	Germanium (IV) chloride GeCl 4 is a liquid with a boiling point of 83 ° C and a density of 1.887 g/cm 3

Scientists who discovered new elements highly appreciated the discovery of the Russian scientist: “There can hardly be a more striking proof of the validity of the doctrine of the periodicity of elements than the discovery of the still hypothetical eca-silicon; it constitutes, of course, more than a simple confirmation of a bold theory - it marks an outstanding expansion of the chemical field of vision, a giant step in the field of knowledge” (K. Winkler).

The American scientists who discovered element No. 101 gave it the name “mendelevium” in recognition of the great Russian chemist Dmitri Mendeleev, who was the first to use the Periodic Table of Elements to predict the properties of then undiscovered elements.

You met in 8th grade and will be using a form of the periodic table this year called the short period form. However, in specialized classes and in higher education, a different form is predominantly used - the long-period version. Compare them. What are the same and what are different about these two forms of the Periodic Table?

New words and concepts

Periodic law of D. I. Mendeleev.
The periodic table of chemical elements by D.I. Mendeleev is a graphical representation of the Periodic Law.
The physical meaning of element number, period number and group number.
Patterns of changes in the properties of elements in periods and groups.
The meaning of the Periodic Law and the Periodic Table of Chemical Elements by D. I. Mendeleev.

Tasks for independent work

Prove that the Periodic Law of D.I. Mendeleev, like any other law of nature, performs explanatory, generalizing and predictive functions. Give examples illustrating these functions of other laws known to you from chemistry, physics and biology courses.
Name a chemical element in the atom of which electrons are arranged in levels according to a series of numbers: 2, 5. What simple substance does this element form? What is the formula of its hydrogen compound and what is it called? What is the formula of the highest oxide of this element, what is its character? Write down the reaction equations characterizing the properties of this oxide.
Beryllium was previously classified as a Group III element, and its relative atomic mass was considered to be 13.5. Why did D.I. Mendeleev move it to group II and correct the atomic mass of beryllium from 13.5 to 9?
Write the reaction equations between a simple substance formed by a chemical element, in an atom of which electrons are distributed among energy levels according to a series of numbers: 2, 8, 8, 2, and simple substances formed by elements No. 7 and No. 8 in the Periodic Table. What type of chemical bond is present in the reaction products? What crystal structure do the original simple substances and the products of their interaction have?
Arrange the following elements in order of increasing metallic properties: As, Sb, N, P, Bi. Justify the resulting series based on the structure of the atoms of these elements.
Arrange the following elements in order of increasing non-metallic properties: Si, Al, P, S, Cl, Mg, Na. Justify the resulting series based on the structure of the atoms of these elements.
Arrange in order of weakening acidic properties the oxides whose formulas are: SiO 2, P 2 O 5, Al 2 O 3, Na 2 O, MgO, Cl 2 O 7. Justify the resulting series. Write down the formulas of the hydroxides corresponding to these oxides. How does their acidic character change in the series you proposed?
Write the formulas of boron, beryllium and lithium oxides and arrange them in ascending order of their main properties. Write down the formulas of the hydroxides corresponding to these oxides. What is their chemical nature?
What are isotopes? How did the discovery of isotopes contribute to the development of the Periodic Law?
Why do the charges of the atomic nuclei of elements in the Periodic Table of D.I. Mendeleev change monotonically, that is, the charge of the nucleus of each subsequent element increases by one compared to the charge of the atomic nucleus of the previous element, and the properties of the elements and the substances they form change periodically?
Give three formulations of the Periodic Law, in which the relative atomic mass, charge of the atomic nucleus and the structure of external energy levels in the electron shell of the atom are taken as the basis for the systematization of chemical elements.