Periodic system of chemical elements of D. I. Mendeleev

Basic concepts:

1. Ordinal number of a chemical element- the number given to the element when it is numbered. Shows the total number of electrons in an atom and the number of protons in the nucleus, determines the charge of the nucleus of an atom of a given chemical element.

2. Period- chemical elements arranged in a line (there are 7 periods in total). The period determines the number of energy levels in an atom.

Small periods (1 - 3) include only s - and p - elements (elements of the main subgroups) and consist of one line; large (4 - 7) include not only s - and p - elements (elements of the main subgroups), but also d - and f - elements (elements of secondary subgroups) and consist of two lines.

3. Groups- chemical elements arranged in a column (only 8 groups). The group determines the number of outer level electrons for elements of the main subgroups, as well as the number of valence electrons in an atom of a chemical element.

Main subgroup (A)– includes elements of large and small periods (only s - and p - elements).

Side subgroup (B)- includes elements of only large periods (only d - or f - elements).

4. Relative atomic mass (A r) – shows how many times a given atom is heavier than 1/12 of a 12 C atom, this is a dimensionless value (for calculations, a rounded value is taken).

5. Isotopes- a variety of atoms of the same chemical element, differing from each other only in their mass, with the same serial number.

The structure of the atom

Basic concepts:

1. Electronic cloud is a model of quantum mechanics that describes the motion of an electron in an atom.

2. Orbital (s, p, d, f) - part of the atomic space in which the probability of finding a given electron is the highest (~ 90%).

3. Energy level- this is an energy layer with a certain energy level of the electrons located on it.

The number of energy levels in an atom of a chemical element is equal to the number of the period in which this element is located.

4. The maximum possible number of electrons at a given energy level is determined by the formula:

N = 2 n 2 , where n is the period number

5. The distribution of orbitals by levels is represented by the scheme:

6. Chemical element A type of atom with a certain nuclear charge.

7. Composition atom :

Particle	Charge		Weight
	Cl	conventional units		a.u.m.
Electron (ē)	1.6 ∙ 10 -19		9.10 ∙ 10 -28	0.00055
Proton ( p)	1.6 ∙ 10 -19		1.67 ∙ 10 -24	1.00728
Neutron ( n)			1.67 ∙ 10 -24	1.00866

8. Composition atomic nucleus:

The nucleus is made up of elementary particles

protons(p) and neutrons(n).

Since Almost all the mass of an atom is concentrated in the nucleus rounded valueA rof a chemical element is equal to the sum of protons and neutrons in the nucleus.

9. The total number of electrons in the electron shell of an atom is equal to the number of protons in the nucleus and the atomic number of the chemical element.

The order of filling levels and sublevels with electrons

I. The electronic formulas of atoms of chemical elements are in the following order:

First, by the number of the element in the table of D. I. Mendeleev, the total number of electrons in the atom is determined;

Then, according to the number of the period in which the element is located, the number of energy levels is determined;

Levels are divided into sublevels and orbitals, and fill them with electrons in accordance The principle of least energy

For convenience, electrons can be distributed over energy levels using the formula N \u003d 2n 2 and taking into account the fact that:

1. at the elements main subgroups(s -; p -elements) the number of electrons in the outer level is equal to the group number.

2. at the elements side subgroups usually on the outside two electron (with the exception of atoms Cu, Ag, Au, Cr, Nb, Mo, Ru, Rh, whose outer level one electron, at Pd at the outer level zero electrons);

3. The number of electrons in the penultimate level is equal to the total number of electrons in the atom minus the number of electrons in all other levels.

II. The order in which atomic orbitals are filled with electrons is determined by:

1.Principle of least energy

Energy scale:

1s<2s<2p<3s<3p<4s<3d<4p<5s<4d<5p<6s<4f<5d<6p<7s…

2. The state of an atom with a completely or half-filled sublevel (ie, when there is one unpaired electron in each orbital) is more stable.

This explains the "failure" of the electron. Thus, the following distribution of electrons corresponds to the stable state of the chromium atom:

Cr: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 5 , ane 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 4 ,

i.e., there is a "failure" of the electron from the 4s sublevel to the 3d sublevel.

III. Families of chemical elements.

Elements in whose atoms the s-sublevel is filled with electrons external s-elements. These are the first 2 elements of each period, constituting the main subgroups I and II groups.

Elements in whose atoms the p-sublevel is filled with electrons external energy level are called p-elements. These are the last 6 elements of each period (with the exception of I and VII), constituting the main subgroups III- VIII groups.

Elements in which the d-sublevel is filled second outside the level are called d-elements. These are elements of intercalary decades IV, V, VI periods.

Elements in which the f-sublevel is filled third outside the level are called f-elements. The f-elements include lanthanides and actinides.

Periodic law of D. I. Mendeleev

The properties of simple substances, as well as the forms and properties of compounds of elements, are in a periodic dependence on the magnitude of the atomic weights of the elements.

The modern formulation of the periodic law.

The properties of chemical elements and their compounds are in a periodic dependence on the magnitude of the charge of the nuclei of their atoms, which is expressed in the periodic repetition of the structure of the outer valence electron shell.

Key points

1. In the period from left to right:

2) The charge of the nucleus - increases

3) The number of energy levels - constantly

4) The number of electrons at the outer level - increases

5) The radius of atoms - decreases

6) Electronegativity - increases

Consequently, the outer electrons are held tighter, and the metallic (reductive) properties are weakened, while the non-metallic (oxidizing) properties are enhanced.

2. In the group, in the main subgroup from top to bottom:

1) Relative atomic mass - increases

2) The number of electrons in the outer level is constant

3) The charge of the nucleus - increases

4) The number of energy levels - increases

5) Radius of atoms - increases

6) Electronegativity - decreases.

Consequently, external electrons are held weaker, and the metallic (reducing) properties of the elements are enhanced, while the non-metallic (oxidative) properties are weakened.

3. Change in the properties of volatile hydrogen compounds:

1) in groups of main subgroups, with an increase in the charge of the nucleus, the strength of volatile hydrogen compounds decreases, and the acidic properties of their aqueous solutions increase (basic properties decrease);

2) in periods from left to right, the acidic properties of volatile hydrogen compounds in aqueous solutions increase (basic ones decrease), and the strength decreases;

3) in groups with an increase in the charge of the nucleus in the main subgroups, the valency of the element in volatile hydrogen compounds does not change, in periods from left to right it decreases from IV to I.

4. Change in the properties of higher oxides and their corresponding hydroxides (oxygen-containing acids of non-metals and metal bases):

1) in periods from left to right, the properties of higher oxides and their corresponding hydroxides change from basic through amphoteric to acidic;

2) the acidic properties of higher oxides and their corresponding hydroxides increase with increasing nuclear charge in the period, the basic ones decrease, and the strength decreases;

3) in the groups of the main subgroups of higher oxides and their corresponding hydroxides, with an increase in the charge of the nucleus, the strength increases, the acidic properties decrease, the basic ones increase;

4) in groups with an increase in the charge of the nucleus in the main subgroups, the valency of the element in higher oxides does not change, in periods from left to right it increases from I to VIII.

5. Completeness of the outer level - if there are 8 electrons on the outer level of the atom (for hydrogen and helium 2 electrons)

6. Metal properties - the ability of an atom to donate electrons before the completion of the external level.

7. Non-metallic properties - the ability of an atom to accept electrons before the completion of the outer level.

8. Electronegativity the ability of an atom in a molecule to attract electrons to itself

9. Families of elements:

Alkali metals (1 group "A") -Li, Na, K, Rb, Cs, Fr

Halogens (group 7 "A") -F, Cl, Br, I

Inert gases (group 8 "A") -He, Ne, Ar, Xe, Rn

Chalcogens (group 6 "A") -O, S, Se, Te, Po

Alkaline earth metals (group 2 "A") -Ca, Sr, Ba, Ra

10. Radius of an atom is the distance from the nucleus of an atom to the outer level

Tasks for fixing:

Development of an outline of the lesson "The Periodic Law and the Periodic Table of Chemical Elements by D.I. Mendeleev"

Teacher: Potokina Nina Nikolaevna

MOU SOSH N47 Tver

Subject: "The periodic law and the periodic system of chemical elements of D.I. Mendeleev»

The purpose of the lesson: a) cognitive aspect:

To control the degree of assimilation of ZUN, formed in the previous lesson: drawing up diagrams of the structure of atoms, defining the concepts: “element-metal”, “element-non-metal”

Ensure the assimilation of the following basic knowledge included in the content of the topic of the lesson:

Definition of concepts: "periodicity", "periodic law"

Characteristics of the structure of the periodic system

The meaning of the periodic law

3.Form the following special skills:

Explanation of the reason for the periodic change in the properties of chemical elements

Establishment of the physical meaning of the serial number of the element, group number, period number, periodic law.

Identification of patterns of change in metallic and non-metallic properties of elements in periods and in groups

b) developing aspect:

Provide, using tasks that require the performance of mental operations of various levels of complexity, the formation of independent judgments of students, intellectual and educational and communicative skills and abilities:

Speech development (enrichment and complication of vocabulary, complication of the semantic function of speech)

Formation of attention, writing and reading techniques

Formation of mental operations (analysis and synthesis, highlighting the main and essential, abstraction and concretization, comparison and distinction)

c) educational aspect:

1. To assist during the lesson in the formation of the scientific worldview of students:

Confidence in the materiality of the world by revealing the nature of the studied phenomena

Understanding the objective nature of the studied law, the possibility of knowing nature and using this knowledge in scientific and practical activities

Establishment of cause-and-effect relationships: composition - structure - properties

2. To carry out moral education (patriotism, internationalism, camaraderie, ethical standards of behavior)

3. To form respect for science as part of the culture of society.

Motivation: showing the importance of new knowledge

For the development of science

In life-cognitive experience

In the learning process (the presence of basic knowledge about the position of the element in D.I. Mendeleev’s PSCE and the structure of its atom ensures the assimilation of the material of subsequent topics; allows you to establish cause-and-effect relationships)

During the classes

organizational stage.

Homework verification stage (composition and structure of atoms, metal, non-metal)

The stage of preparing students for active and conscious assimilation of new material (telling the topic of the lesson, formulating goals together with students: a) to learn the new concept of "periodic law" b) to study the structure of the periodic system c) to establish a connection between the periodic law and the periodic system and the structure of the atom d) evaluate the value of the periodic law Motivation Lesson objectives: organization of further activities of students in the study and assimilation of new material (work in four groups with cognitive texts, followed by commenting on the material according to the outline scheme) Work algorithm:

new material

Educational text No. 1 "Periodic law"

Formed concepts: "periodicity", "periodic law" Questions for conclusion: a) Can we say that the periodic law exists in nature really?

b) What is the merit of D.I. Mendeleev?

Educational text No. 2 "Periodic system of chemical elements of D. I. Mendeleev"

Formed concepts: "Periodic system of chemical elements of D. I. Mendeleev", "periods", "groups", "main and secondary subgroups"

Conclusion Questions: Are the Periodic System and the Periodic Table the same concepts?

Educational text No. 3 "Periodic law and the periodic system in the light of the doctrine of the structure of the atom"

Formed concepts: the physical meaning of the periodic law, period number, group number

Questions for conclusion: Why is there a periodic dependence of the properties of elements and substances formed by them on the charge of the atomic nucleus?

Educational text No. 4 "The meaning of the periodic law"

Formed concepts: materiality, unity and cognizability of the world, interconnection of phenomena

Questions for conclusion: What facts prove the scientific nature of the law discovered by D.I. Mendeleev

Consolidation stage (Answers to questions and test tasks contained in educational texts)

Diagnostic work

1. Select schemes of chemical elements:

1B. Second period 2B Third period

a) 2e, 8e b) 2e, 8e, 5e c) 1e d) 2e, 8e, 8e, 1e

2.Select blueprints:

1B of the Third group 2B of the Sixth group

a) 2f, 8e, 6f b) 1s 2 2s 2 2p 6 3s 2 3p 1 c) 1s 2 2s 1 d) 1s 2 2s 2 2p 6

3. The most pronounced 1B metallic 2B non-metallic properties are expressed in: a) 1s 2 2s 2 b) 1s 2 2s 1 c) 1s 2 2s 2 2p 1 d) 1s 2 2s 2 2p 2

4. Cause 1B Strengthening of metallic properties in periods

2B Strengthening of metallic properties in groups:

a) an increase in the number of EMs b) an increase in the number of electrons on a wind turbine c) an increase in the nuclear charge d) an increase in the mass of an atom

The stage of informing students about homework

Lesson conclusions:

PP exists and acts in nature really and independently of human consciousness. A person only discovers the law, i.e., cognizes the connection of phenomena and expresses it in the formulation: “the properties of elements and their compounds are in a periodic dependence on the charge of the nucleus of their atom”

The periodic system is a natural classification of chemical elements. Periodic table - graphic representation of the periodic law

The properties of the elements change periodically, because the number of electrons at the outer level of their atoms periodically changes

PZ is not a hypothesis, but a scientific theory, because performs three main functions: generalizing, explanatory and predictive

(PSCE D.I. Mendeleev is a single whole, including all chemical elements, because they have common features of the structure of atoms, common properties; PZ shows the relationship of composition-structure-properties; PZ allows you to predict the existence and properties of yet undiscovered elements )

Scheme - abstract

PZ D.I.MENDELEEV Came! 1.D.I. Mendeleev compared all chemical elements with each other. 2. I took atomic masses as the basis for comparison. Had seen! Repetition of similar elements of metals and non-metals at regular intervals. Won! 1. Classified all chemical elements by creating a periodic system. 2. Formulated a periodic law: "the properties of elements and their compounds are in a periodic dependence on the charge of the nucleus of their atom"

Block 2 As a formula, as a labor schedule The structure of the Mendeleev system The world is around you Enter it, breathe it in, touch it with your hands! S.Schipachev (Horizontal rows) Small(1,2,3) 1- 2 elements, 2,3- 8 elements each Large(4,5,6,7);. 4.5-18 elements 6-32 elements 7 unfinished From left to right, metallic properties decrease and non-metallic properties increase. Home Side (elements of both small and large periods) (elements of large periods only) From top to bottom, metallic properties are enhanced, while non-metallic properties are weakened. structure

Block 3 PZ and PSHE in the light of the doctrine of the structure of the atom Physical meaning: Ordinal number \u003d charge of the nucleus of an atom (Z) period number = number of EC (energy levels) group number = number of electrons in the wind turbine (external energy level) Period: Z, the number of electrons per wind turbine increases, the number of electrons =const The radius of the atom decreases, the attraction of electrons to the nucleus increases Group: Z, the number of EMs, the radius of the atom increase, the number of electrons per wind turbine = const, the attraction of electrons to the nucleus decreases Metallicity - recoil of electrons Non-metallicity - addition

Block4 PV value PP allowed: 1. Correct atomic masses 2. Predict the existence and properties of yet undiscovered elements The PZ served as an impetus for the development of atomic physics, geochemistry, biochemistry, space chemistry... PP confirmed the laws of nature: Unity and materiality of the world Knowability of the world The relationship of phenomena “The world is complex. It is full of events, doubts And the secrets of endless and bold guesses. How a miracle of nature is born a genius And in this chaos brings order.

Educational text 1 "Periodic law of D.I. Mendeleev"

Task: give the formulation of the periodic law, explain the concept of periodicity

By the middle of the 19th century, more than 60 chemical elements were discovered, most of which had their physical and chemical properties studied. The discovery of new elements and the study of the properties of elements and their compounds made it possible, on the one hand, to accumulate rich factual material, and on the other hand, revealed the need for its systematization.

None of the attempts at classification revealed a basic pattern in their arrangement and, therefore, could not lead to the creation of a natural system that encompasses all elements and reflects the nature of their similarities and differences.

As a basis for comparing all chemical elements, D.I. Mendeleev took the fundamental quantitative characteristic of an element - atomic mass.

D.I. Mendeleev arranged all known elements in ascending order of atomic masses: Li– Be – B – C – N – O – F– Ne – Na– Mg – Al – Si – P – S – Cl…

And he discovered that in the natural series of elements he obtained, similar elements (Li - Na - alkali metals; F - Cl - typical non-metals "halogens") are repeated at regular intervals. This pattern was called by D.I. Mendeleev the law of periodicity and formulated as follows:

The properties of simple bodies, as well as the form and properties of compounds of chemical elements, are in a periodic dependence on the magnitude of the atomic masses of the elements.

D.I. Mendeleev broke the natural series into segments that began with an alkali metal, placed the segments one below the other and received a system of chemical elements

Li– Be – B – C – N – O – F– Ne

Na– Mg – Al – Si – P – S – Cl

This arrangement reflected the periodicity of changes in the properties of chemical elements.

Questions: 1) What property of the element D.I. Mendeleev put as the basis for the classification?

2) Explain the expression "element properties change periodically"? What properties of elements change periodically?

Educational text 2 “The Periodic Table of Chemical Elements D.I. Mendeleev"

Task: Explain the expression "the periodic system is the natural classification of chemical elements, and the table is a graphic representation of the periodic law"

1. As a result of comparing the properties and atomic masses of elements, D.I. Mendeleev came to the discovery of PZ and, on its basis, PSCE, i.e. PSCE really exists in nature, is a natural classification of chemical elements.

The table we are using is a graphical representation of the software. Currently, the most common forms of the table are short and long. The short form of the table was developed by D.I. Mendeleev in 1870, it is called classical. (The first version, proposed in 1869, had a long form

i.e., in it, the periods were arranged in one line) At school, they study the short form of the table. What is its structure?

2. Periods - horizontal rows of elements, within which the properties of the elements change sequentially. Periods are divided into small (1 period - 2 elements; 2.3 periods - 8 elements each) and large

(4.5 periods - 18 elements each; 6 period - 32 elements; 7 period - unfinished)

In all periods, with an increase in the ordinal number of the element (LEFT TO RIGHT), the metallic properties decrease, and the non-metallic ones increase.

3. Groups are vertical columns of elements, there are eight of them.

Each group consists of 2 subgroups: main and secondary.

The main subgroup includes elements of both small and large periods.

The secondary subgroup includes elements of only large periods.

For example: 1 group main subgroup: H, Li, Na, K, Rb, Cs, Fr; side subgroup - Cu, Ag, Au.

Elements with similar properties are combined into a subgroup: from top to bottom, the metallic properties of elements are enhanced, while non-metallic properties are weakened. Using PSCE, one can give a comparative description of the properties of any element.

Tests: 1. Element No. 20 is located: a) 5p, 4 gr., Ch. subgroup b) 4p, 5 gr., Ch. subgroup c) 4p, 2gr., ch. subgroup 2p, 4 gr., ch. subgr.)

2. In group 3 Ch. subgroup is: a) Na b) Mg c) Al d) C

3 The most pronounced metallic properties are expressed in: a) Na b) Mg c) Al

4 The most pronounced metallic properties are expressed in: a) Li, b) Na, c) K

5 The most pronounced non-metallic properties are expressed in: a) N b) O c) F

6 The most pronounced non-metallic properties are expressed in: a) C b) Si c) Ge

Educational text3 "Periodic law and the periodic system in the light of the doctrine of the structure of the atom"

Task: Give the modern wording of the PP. Why is the nuclear charge (serial number) the main characteristic of an element?

After the creation of the PSCE, scientists faced a number of questions. How many elements should the PSCE contain? Why do the properties of elements change periodically, because the atomic mass changes continuously? Why do the metallic properties of elements weaken with increasing atomic mass in a period, and increase in a group? Data on the structure of the atom made it possible to elucidate the physical meaning of PZ and answer many questions. Comparison of the properties of the element and the structure of its atom leads to the conclusion: the main characteristic of the element is its serial number, since. it is equal to the charge of the nucleus of an atom. The charge of the nucleus determines the number of electrons in an atom, which are located in a certain way around the nucleus, the nature of the distribution of electrons around the nucleus determines the chemical properties of atoms. The modern wording of the PP:

The properties of elements, as well as their compounds, are in a periodic dependence on the charge of the atomic nucleus.

Within the period, there is a gradual accumulation of electrons in the outer layer from 1 to 8, so there is a smooth change in the metallic properties of the element to non-metallic ones. The number of ES remains unchanged and coincides with the number of the period.

Within the group of the main subgroup, the number of electrons on the wind turbine remains unchanged, equal to the number of the group. The number of ECs changes, therefore, the radius of the atom increases, the attraction of electrons to the nucleus decreases, which explains the growth from top to bottom of metallic and the decrease in non-metallic properties of elements.

The properties of the elements are periodically repeated, because with an increase in the charge of the nucleus of an atom, the number of electrons on the wind turbine of the element atom is periodically repeated (the physical meaning of PZ). In most cases, with an increase in the charge of the nucleus of the atoms of elements, their relative atomic masses also increase. This circumstance allowed D.I. Mendeleev to discover PZ long before the discovery of the structure of the atom.

Tests: 1Choose the name of the element that has 8 electrons on the wind turbine:

a) neon, b) fluorine, c) boron, d) oxygen

2.4EU contains the electron shell of the atom:

a) silicon, b) silver, c) potassium d) beryllium

3Electronic circuit +X) 2) 5 corresponds to:

a) boron, b) silver, c) chlorine, d) nitrogen

4. Complete the formula 1s 2 2s 2 ... 3s 1, select the name of the chemical element to which it belongs: a) aluminum, b) lithium, c) sodium, d) nitrogen

5. Complete the formula + X) 2) ...) 3, select the name of the chemical element to which it belongs: a) aluminum, b) lithium, c) sodium, d) nitrogen

Educational text 4. "The meaning of the periodic law"

Exercise: assessing the significance of the discovery of DIMendeleev, F.Engels wrote: Mendeleev accomplished a scientific feat that can be safely put next to the discovery of Le Verrier, who calculated the orbit of the unknown planet Neptune. What is the scientific feat of D.I. Mendeleev?

1) Everything seemed simple: write the symbols of chemical elements, their atomic masses; arrange the cards in ascending order of atomic masses. BUT, let's imagine the middle of the 19th century. What did Mendeleev's contemporaries know? 63 elements. Some of them were not well purified from impurities, and this led to a distortion of atomic masses, the properties of elements. There were many empty cells in the table. In order not to disturb the periodicity, D.I. Mendeleev was forced to correct the atomic masses of some elements (so the mass of beryllium was considered 13.5, the metal beryllium fell between two non-metals carbon and nitrogen. Mendeleev corrects the mass of beryllium to the average and puts it between lithium and boron (7 +11):2=9). Subsequent studies have confirmed this. And then it was a bold move. In addition, the scientist was forced to allow 3 permutations: Element No. 18 argon has a mass of 40, and element No. 19 potassium has a mass of 39 (No. 27 and No. 28; No. 52 and No. 53). This was perceived by most scientists as scientific frivolity, unreasonable insolence.

2) D.I. Mendeleev takes another bold step: he describes in detail the property of elements that are still unknown to anyone. The further development of experimental chemistry convincingly confirmed Mendeleev's predictions. What was the surprise and admiration of scientists from different countries when, having discovered a new element, they discovered an exact match of its properties with the predictions of D.I. Mendeleev. The periodic system of chemical elements has become a compass in the research of scientists. Based on it, they began to discover new chemical elements, to create new substances with properties predicted in advance. Progress is associated with the periodic law not only in science (the interconversion of elements, the search for ways to release nuclear energy, the production of isotopes, the development of physics, geochemistry, biochemistry, space chemistry), but also in technology: PZ opens the law of distribution of metals in the earth's crust, helping to search for useful fossils. Metallurgists have found a connection between PSCE and the role and behavior of the elements in special steels. Thus, the boundaries of the law are extensive: they cover the chemical elements of the Universe, and the simple and complex substances formed by them. During the life of D.I. Mendeleev, PZ relied on the atomic and molecular theory, today on the electronic theory of the structure of the atom, continuing to live and develop.

How do you understand the expression: "The law, being an instrument of knowledge, performs 3 functions: generalizing, explaining, prognostic."?

Subject: Repetition and generalization of knowledge on the topic: "Periodic system of chemical elements of D.I. Mendeleev and the structure of the atom."

Target:

repeat and summarize knowledge on the topic covered;

continue to instill a love of chemistry;

develop the ability to generalize, compare, draw conclusions;

use computer technology to adapt deaf students to the modern world;

to develop the speech of students, to promote the assimilation of the chemical dictionary;

to cultivate independence, mutual assistance, self-control, the ability to interact with each other.

Lesson type - a lesson in repetition and generalization of knowledge

Lesson equipment - periodic table, cards, computers, accounting sheets,

tokens, pictures for reflection.

Vocabulary - protons, neutrons, electrons, nuclear charge, group, period, metal, non-metal, atomic mass, serial number, energy level

During the classes.

A. Organizational moment Officer's report. Greetings. Introduction to the topic of the lesson and the objectives of the lesson.

Today in the lesson we will make a journey in which we will repeat and bring into the system knowledge on the topic of the lesson. But in order to go on a trip, it is necessary to decipher the name of the country we are going to.

Name the country to which we will travel.

Work in groups of 3 people.

structure

atom

structure

nuclei

That's right, the country is called Chemical Elementary.So, we will visit several stations where we will have to complete tasks.

Stations:

1. Repeat (Mendeleev quiz)

Get to Know (Practical)

Have a rest

Light up the Christmas tree

B. Repetition and generalization of the topic. 2. Stations:

Repeat (Mendeleevskaya quiz)

Students receive a token for each correct answer.

Which scientist discovered the periodic table of chemical elements?

In what year was the Periodic Table of Chemical Elements created by D.I. Mendeleev?

What are the horizontal rows in a table called?

How many periods are in the table?

What does period number show?

How many groups are in the PSCE?

What does the group number show?

What does the atomic number of a chemical element indicate?

What are the elements?

Which non-metal is the strongest?

What metal is the strongest?

In the control sheets, put such a figure, how many tokens you received.

Practical

Give a description of the chemical element according to the plan:

The sign and name of the element

Home address: group number, main or secondary subgroup, period number, ordinal number, atomic mass.

Number of electrons, protons, neutrons

The structure of the atom

Metal or non-metal?

Swap cards with your neighbor. Check each other's work. Put the score on the checklist. If there are no errors - put 5, if 1.2 mistakes - put 4, if 3.4 mistakes - put 3, if 5 or more mistakes - put 2

Get some rest.

The teacher shows the element .. If it is metal, then the students should clap their hands, and if it is non-metal, they stomp their feet.

Light the fire. (work on computers)

In the control sheet, put such a figure, how many tokens you received

AT. Summing up and reflection.

Guys, we have finished our journey and it's time for us to go home, the train is waiting for us, but there were no tickets for one carriage.

Calculate how many points each of you scored for the lesson. If you typed

10 points or more - put yourself a 5, you have a ticket to the red car,

8.9 points - put 4, you have a green car,

6.7 points is 3 and a blue car.

The trailers are on your tables. Sign them and stick them on the board. Look at what a beautiful train we are going home. I hope that next time you will all ride only in red cars. See you.

Give a description of the chemical element No. 4 according to the plan:

The sign and name of the element

Home address: Group No.

period number

small or big

atomic mass.

Number of electrons

protons

neutrons

The structure of the atom

Number of electrons in the last level

Metal or non-metal?

Give a description of the chemical element No. 5 according to the plan:

The sign and name of the element

Home address: Group No.

main or secondary subgroup

period number

small or big

atomic mass.

Number of electrons

protons

neutrons

The structure of the atom

Number of electrons in the last level

Metal or non-metal?

Give a description of the chemical element No. 6 according to the plan:

The sign and name of the element

Home address: Group No.

main or secondary subgroup

period number

small or big

atomic mass.

Number of electrons

protons

neutrons

The structure of the atom

Number of electrons in the last level

Metal or non-metal?

Give a description of the chemical element No. 7 according to the plan:

The sign and name of the element

Home address: Group No.

main or secondary subgroup

period number

small or big

atomic mass.

Number of electrons

protons

neutrons

The structure of the atom

Number of electrons in the last level

Metal or non-metal?

Give a description of the chemical element No. 8 according to the plan:

The sign and name of the element

Home address: Group No.

main or secondary subgroup

period number

small or big

atomic mass.

Number of electrons

protons

neutrons

The structure of the atom

Number of electrons in the last level

Metal or non-metal?

Give a description of the chemical element No. 9 according to the plan:

The sign and name of the element

Home address: Group No.

main or secondary subgroup

period number

small or big

atomic mass.

Number of electrons

protons

neutrons

The structure of the atom

Number of electrons in the last level

Metal or non-metal?

Give a description of the chemical element No. 10 according to the plan:

The sign and name of the element

Home address: Group No.

main or secondary subgroup

period number

small or big

atomic mass.

Number of electrons

protons

neutrons

The structure of the atom

Number of electrons in the last level

Metal or non-metal?

Describe the chemical element number 11

Sign, element name

Na- sodium

Home address:

group number I subgroup home period number 3 small atomic mass 23

Quantity

electrons 11 protons 11 neutrons 12

The structure of the atom

Na+11)))2ē8ē1ē 2nd 8th 1st

Number of ē on the last level 1e metal or

non-metal? metal

Stations:

1.Repeat

(Mendeleev quiz)

Find out

(Practical)

Have a rest

Light a fire

structure

atom

structure

nuclei

1. Which scientist discovered the periodic table of chemical elements?

What year

was the periodic system of D.I. Mendeleev created?

how

called the horizontal rows in the table?

How many peri-

dov in the table?

What does period number show?

What are the names of the vertical rows in the PSCE?

1. How many groups are in the PSCE?

   What subgroups is each group divided into?

   What does the group number show?

10. What does the element's serial number show?

What are the elements?

How do element properties change from left to right?

How do element properties change from bottom to top?

What non-metal

the strongest?

What metal

the strongest?

protons group neutrons metal electrons CORE

CHARGE non-metal

period number

ATOMIC MASS

energy level

ordinal

Control sheet.

Exercise

Control sheet.

Exercise

Control sheet.

Exercise

Control sheet.

Exercise

Control sheet.

Exercise

Control sheet.

Exercise

Control sheet.

Exercise

State special (correctional) educational institution

for students (pupils) with developmental disabilities boarding school I and II type

Repetition and generalization of knowledge

Sections: Chemistry

Periodic law and periodic system of chemical elements of DIMendeleev.

“Oh, how many wonderful discoveries we have
Prepares enlightenment spirit,
And experience, the son of difficult mistakes,
And genius, paradoxes friend,
And chance, God is an inventor…”

(A.S. Pushkin)

Lesson goals.

Generalize and systematize the knowledge and skills of students on the topic studied. Students should know the terminology on the topic “Periodic law”, the structure of the periodic system of chemical elements of D.I. Mendeleev (PSKhEM) and the structure of the atom, the meaning of the periodic law. To be able to determine the chemical symbol of the element, its position in the PSCM using the electronic formula of the atom, work independently and collectively, highlight the main thing, compare, draw conclusions and forecasts.

Equipment.

Portrait of D.I. Mendeleev, electronic PSKHEM, task cards, envelopes with tasks, tokens for evaluating answers (Cards prepared for printing are located in the applications <Приложение1> – <Приложение4> , quotes for homework are located in <Приложении5> ).

During the classes

(1 minute)

Teacher. Good afternoon guys and guests! Guys, be careful and focused! Our lesson is devoted to the periodic law, PSHEM and the structure of the atom. Let's start the lesson.

1. Warm up. (We work with a table of elements)

(4 minutes)

1. What element does not have a “permanent residence” in the table? (H)
2. What element is named after Russia? (Ruthenium)
3. Which element “says” that it is not it. (neon)
4. Which element is doomed to eternal torment?... historians (Tantalum)
5. Which element is the real giant? (Titanium)
6. Which element revolves around the sun?
7. Which element is named after D.I. Mendeleev? (101 Mendelevium)

Element 101 was first obtained in early 1955 at the Radiation Laboratory of the University of California by a group of American scientists.

What formulation of the Periodic Law was given by D.I. Mendeleev?

What is the current wording of the law?

Of course, the contribution of D.I. Mendeleev in the development of chemistry is enormous, but he did not work on the problem of classifying elements alone. Both before him and after him, discoveries were made that made it possible to reveal the essence of the law and confirm the data that Mendeleev could only assume.

2. Chemical scientists.

(on the board - portraits of scientists)

1. Until now, the model of the atom, proposed in 1911, is used. What scientist proposed it? (Ernest Rutherford, Scottish by birth, one of 12 children)
2. Irish scientist who proposed to call the particles that carry electricity - electrons. Greek - “amber” (1891 George Johnston Stoney)
3. English and French scientist who proved that electrons are negatively charged. (Joseph Thomson and Jean Perrin)
4. One of them calculated the speed of the electron and its mass. (300 thousand km / s, 2 thousand times lighter than hydrogen). (Joseph Thomson)

Question to the class. What is a graphic representation of the Periodic Law? (Periodic table of D.I. Mendeleev)

3. Express exam.

(The teacher in turn offers students cards with questions. Each student must answer once. For a correct answer - a token of a certain color, an incomplete answer - a token of a different color, an incorrect answer - a fine token).

1. What information about the structure of the atom does ...:

(the question on the board is written in the same color as the cards)

2. How to determine using the periodic table ...

(the color of the question is the same as the cards)

4. Working with a spreadsheet and at the blackboard.

(10 minutes)

Teacher. Now let's check in practice how you can apply your knowledge.

(The task is performed by 2 students on the board, the rest in notebooks - number, topic, lesson number)

After the task is completed, the student approaches the spreadsheet and shows the element, the class checks the correctness of the entry on the board. The spreadsheet shows the structure of the atom.

• Write the structure of the atom from No. 6 No. 9
• We complicate the task + 12)2)) ...)2))5
• And even more difficult - the mass of neutrons = the mass of protons = 20. Write the structure of an atom.

Teacher. So, you passed the exam, I checked your knowledge. And now you check the work of one student (writing on the board).

1S 2 2S 2 2P 7 1S 2 2S 2 2P 6 3S

Done with the check. How about encryption? (the teacher distributes one encryption for each desk - work in pairs.) Show the decoded item on the spreadsheet.

ENCRYPTIONS:

Teacher. Guys, you did a great job with this task.

5. Game "Confusion"

1. Differ, chemical, neutrons, element, isotopes, number, one.

(Isotopes of the same chemical element differ in the number of neutrons..)

2. Atom, positive, nucleus, charged. (The nucleus of an atom is positively charged.)

3. Neutrons, the nucleus, and, consists of, an atom, protons, from.

(The nucleus of an atom is made up of protons and neutrons.)

4. Nuclei, determined, masses, and, mass, protons, atom, neutrons, sum.

(The mass of the nucleus of an atom is determined by the sum of the masses of protons and neutrons.)

5. Equals, in, number, number, electrons, protons, atom.

(The number of electrons in an atom is equal to the number of protons.)

6. The number, nucleus, charge, proton, atom, is determined.

(The charge of the nucleus of an atom is determined by the number of protons.)

6. Physical education. - minute. "Living Elements"

Imagine for a moment that you are chemical elements. (Cards with chemical symbols that the children prepared in the first lessons are handed out)

- Come on, stand together in a row - a metal detachment!

And now the squad line up so that the radius has grown!

Where is the strongest metal?

Questions to the team at the desks -

Name the features of the structure of metal atoms.

And now stand before us non-metal friendly row.

How to build decently so that the properties increase?

What is the strongest oxidizing agent?

Questions to the team at the desks -

What are the features of the structure of atoms of non-metals.

7. And now we play “yes - no - ku”.

(3 minutes)

(if the sentence is true, we write “+”, if it is incorrect, “-”)

1. The year of discovery of the periodic law by D.I. Mendeleev is considered 1834. (-)
2. The physical meaning of the serial number of a chemical element is that it determines the atomic mass of the element. (-)
3. The number of protons in the nucleus of an atom is equal to the number of electrons; (+)
4. The metallic properties weaken from left to right; (+)
5. The principle of filling energy cells with electrons was proposed by the chemist Pauli (+)

SELF-TEST

(2 minutes)

(answers on the board, hidden behind a blank sheet)

And here is the answer to the first question of the dictation. Apply a reagent on the sheet in advance - KCNS and distribute iron (III) chloride from a spray gun, 1869 - the year of the discovery of the law.

SUMMING UP

(2 minutes)

- Make a conclusion about the change in the properties of elements within the same period.

- Make a conclusion about the change in the properties of elements within the same group.

- How are changes in the properties of elements and the ability to donate or accept electrons related?

This pattern will form the basis of our next topic - "Chemical bond".

Homework - find sayings of famous people about the meaning of the Periodic Law

Grading, comments, evaluation of the lesson by students.

Guys, thanks for the tutorial! I will end it with lines from S. Shchipachev’s poem “Reading Mendeleev”:

“There is nothing else in nature
Neither here nor there, in the depths of space:
Everything from small grains of sand to planets -
It consists of single elements.
Like a formula, like a labor schedule,
The structure of the Mendeleev system is strict.
Around you is happening, the world is alive,
Enter it, breathe it in, touch it with your hands.”

Periodic law D.I. Mendeleev and the Periodic Table of Chemical Elements is of great importance in the development of chemistry. Let's plunge into 1871, when professor of chemistry D.I. Mendeleev, through numerous trial and error, came to the conclusion that "... the properties of the elements, and therefore the properties of the simple and complex bodies they form, stand in a periodic dependence on their atomic weight." The periodicity of changes in the properties of elements arises due to the periodic repetition of the electronic configuration of the outer electron layer with an increase in the charge of the nucleus.

Modern formulation of the periodic law is:

"the properties of chemical elements (i.e., the properties and form of the compounds they form) are in a periodic dependence on the charge of the nucleus of atoms of chemical elements."

While teaching chemistry, Mendeleev understood that remembering the individual properties of each element causes difficulties for students. He began to look for ways to create a system method to make it easier to remember the properties of elements. As a result, there was natural table, later it became known as periodical.

Our modern table is very similar to Mendeleev's. Let's consider it in more detail.

periodic table

The periodic table of Mendeleev consists of 8 groups and 7 periods.

The vertical columns of a table are called groups . The elements within each group have similar chemical and physical properties. This is explained by the fact that the elements of one group have similar electronic configurations of the outer layer, the number of electrons on which is equal to the group number. The group is then divided into main and secondary subgroups.

AT Main subgroups includes elements whose valence electrons are located on the outer ns- and np-sublevels. AT Side subgroups includes elements whose valence electrons are located on the outer ns-sublevel and the inner (n - 1) d-sublevel (or (n - 2) f-sublevel).

All elements in periodic table , depending on which sublevel (s-, p-, d- or f-) are valence electrons are classified into: s-elements (elements of the main subgroups I and II groups), p-elements (elements of the main subgroups III - VII groups), d- elements (elements of side subgroups), f- elements (lanthanides, actinides).

The highest valence of an element (with the exception of O, F, elements of the copper subgroup and the eighth group) is equal to the number of the group in which it is located.

For elements of the main and secondary subgroups, the formulas of higher oxides (and their hydrates) are the same. In the main subgroups, the composition of hydrogen compounds is the same for the elements in this group. Solid hydrides form elements of the main subgroups of groups I-III, and groups IV-VII form gaseous hydrogen compounds. Hydrogen compounds of the EN 4 type are more neutral compounds, EN 3 are bases, H 2 E and NE are acids.

The horizontal rows of the table are called periods. Elements in periods differ from each other, but they have in common that the last electrons are at the same energy level ( principal quantum numbern- equally ).

The first period differs from the others in that there are only 2 elements there: hydrogen H and helium He.

There are 8 elements (Li - Ne) in the second period. Lithium Li - an alkali metal begins the period, and closes its noble gas neon Ne.

In the third period, as well as in the second, there are 8 elements (Na - Ar). The alkali metal sodium Na begins the period, and the noble gas argon Ar closes it.

In the fourth period there are 18 elements (K - Kr) - Mendeleev designated it as the first large period. It also begins with the alkali metal Potassium and ends with the inert gas krypton Kr. The composition of large periods includes transition elements (Sc - Zn) - d- elements.

In the fifth period, similarly to the fourth, there are 18 elements (Rb - Xe) and its structure is similar to the fourth. It also begins with the alkali metal rubidium Rb, and ends with the inert gas xenon Xe. The composition of large periods includes transition elements (Y - Cd) - d- elements.

The sixth period consists of 32 elements (Cs - Rn). Except 10 d-elements (La, Hf - Hg) it contains a row of 14 f-elements (lanthanides) - Ce - Lu

The seventh period is not over. It starts with Francium Fr, it can be assumed that it will contain, like the sixth period, 32 elements that have already been found (up to the element with Z = 118).

Interactive periodic table

If you look at Mendeleev's periodic table and draw an imaginary line starting at boron and ending between polonium and astatine, then all metals will be to the left of the line, and non-metals to the right. Elements immediately adjacent to this line will have the properties of both metals and non-metals. They are called metalloids or semimetals. These are boron, silicon, germanium, arsenic, antimony, tellurium and polonium.

Periodic Law

Mendeleev gave the following formulation of the Periodic Law: "the properties of simple bodies, as well as the forms and properties of the compounds of elements, and therefore the properties of the simple and complex bodies formed by them, stand in a periodic dependence on their atomic weight."
There are four main periodic patterns:

Octet rule states that all elements tend to gain or lose an electron in order to have the eight-electron configuration of the nearest noble gas. Because Since the outer s and p orbitals of the noble gases are completely filled, they are the most stable elements.
Ionization energy is the amount of energy required to detach an electron from an atom. According to the octet rule, moving from left to right across the periodic table requires more energy to detach an electron. Therefore, the elements on the left side of the table tend to lose an electron, and those on the right side - to gain it. Inert gases have the highest ionization energy. The ionization energy decreases as you move down the group, because electrons at low energy levels have the ability to repel electrons from higher energy levels. This phenomenon is called shielding effect. Due to this effect, the outer electrons are less strongly bound to the nucleus. Moving along the period, the ionization energy gradually increases from left to right.

electron affinity is the change in energy upon acquisition of an additional electron by an atom of a substance in a gaseous state. When moving down the group, the electron affinity becomes less negative due to the screening effect.

Electronegativity- a measure of how strongly it tends to attract the electrons of another atom bound to it. Electronegativity increases as you move periodic table left to right and bottom to top. It must be remembered that noble gases do not have electronegativity. Thus, the most electronegative element is fluorine.

Based on these concepts, let's consider how the properties of atoms and their compounds change in periodic table.

So, in a periodic dependence are such properties of an atom that are associated with its electronic configuration: atomic radius, ionization energy, electronegativity.

Consider the change in the properties of atoms and their compounds depending on the position in periodic table of chemical elements.

The non-metallicity of the atom increases when moving in the periodic table left to right and bottom to top. Concerning the basic properties of oxides decrease, and acid properties increase in the same order - from left to right and from bottom to top. At the same time, the acidic properties of oxides are the stronger, the greater the degree of oxidation of the element forming it

By period from left to right basic properties hydroxides weaken, in the main subgroups from top to bottom, the strength of the bases increases. At the same time, if a metal can form several hydroxides, then with an increase in the degree of oxidation of the metal, basic properties hydroxides weaken.

By period from left to right the strength of oxygen-containing acids increases. When moving from top to bottom within the same group, the strength of oxygen-containing acids decreases. In this case, the strength of the acid increases with an increase in the degree of oxidation of the acid-forming element.

By period from left to right the strength of anoxic acids increases. When moving from top to bottom within the same group, the strength of anoxic acids increases.

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