Lesson 4. Chemical elements. Signs of chemical elements. Relative atomic mass.

Chemical element- a collection of atoms of the same type.

Why were identical atoms named this way?The word “element” (Latin elementum) was used in antiquity (Cicero, Ovid, Horace) as part of something (an element of speech, an element of education, etc.). In ancient times there was a common saying: “Just as words are made up of letters, so bodies are made up of elements.” Hence the probable origin of this word: by the name of a series of consonant letters in the Latin alphabet: l, m, n, t (“el” - “em” - “en” - “tum”).

CHEMICAL LANGUAGE

Humanity uses many different languages. In addition to natural languages ​​(Japanese, English, Russian - more than 2.5 thousand in total), there are also artificial languages, for example, Esperanto. Among artificial languages, languages ​​of various sciences stand out. So, chemistry uses its own chemical language. Chemical language is a system of symbols and concepts designed for a brief, succinct and visual recording and transmission of chemical information. A message written in most natural languages ​​is divided into sentences, sentences into words, and words into letters.

You and I will speak in a special, chemical language. In it, as in our native Russian, we will first learn letters - chemical symbols, then we will learn to write words - formulas - based on them, and then, with the help of the latter, sentences - equations of chemical reactions:

Bulgarian enlighteners Cyril and Methodius are the authors of the Slavic alphabet. But the father of chemical writing is the Swedish scientist J. Ya. Berzelius, who proposed using the initial letters of their Latin names as letters - symbols of chemical elements, or, if the names of several elements begin with this letter, then adding another one to the initial letter subsequent letters of the name.

Chemical signs (chemical symbols) - letter designations of chemical elements. Consist of the first or the first and one of the following letters of the Latin name of the element, for example, carbon - C (Carboeum), calcium - Ca (Calcium), cadmium - Cd...

Chemical element symbolis a symbol for a chemical element.

Historical reference: Chemists of the ancient world and the Middle Ages used symbolic images, letter abbreviations, and combinations of both to denote substances, chemical operations and instruments. The seven metals of antiquity were depicted with astronomical signs of the seven celestial bodies: the Sun ( ☉, gold), Moon (☽ , silver), Jupiter (♃ , tin), Venus (♀, copper), Saturn (♄ , lead), Mercury (☿, mercury), Mars (♁, iron).

Metals discovered in the 15th-18th centuries - bismuth, zinc, cobalt - were designated by the first letters of their names. The sign for wine spirit (Latin spiritus vini) is made up of the letters S and V. The signs for strong vodka (Latin aqua fortis, nitric acid) and golden vodka (Latin aqua regis, aqua regia, a mixture of hydrochloric and nitric acids) are made up of the sign for waterÑ and capital letters F and R respectively. The glass sign (Latin vitrum) is formed from two letters V - straight and inverted.

Attempts to streamline ancient chemical signs continued until the end of the 18th century. At the beginning of the 19th century, the English chemist J. Dalton proposed denoting atoms of chemical elements with circles, inside which were placed dots, lines, initial letters of the English names of metals, etc.

Dalton's chemical symbols gained some popularity in Great Britain and Western Europe, but were soon supplanted by purely alphabetic symbols, which the Swedish chemist J. J. Berzelius proposed in 1814. The principles he expressed for composing chemical symbols have remained valid to this day. In Russia, the first printed message about Berzelius's chemical signs was made in 1824 by the Moscow doctor I. Ya. Zatsepin.

RELATIVE ATOMIC MASS

Historical reference: During his lectures, the English scientist John Dalton (1766–1844) showed students models of atoms carved from wood, showing how they could combine to form various substances. When one of the students was asked what atoms are, he replied: “Atoms are colored wooden blocks that Mr. Dalton invented.”

Of course, Dalton became famous not for his abs or even for becoming a school teacher at the age of twelve. The emergence of modern atomic theory is associated with the name of Dalton. For the first time in the history of science, he thought about the possibility of measuring the masses of atoms and proposed specific methods for this. It is clear that it is impossible to weigh atoms directly. Dalton talked only about “the ratio of the weights of the smallest particles of gaseous and other bodies,” that is, about their relative masses. And to this day, although the mass of any atom is known exactly, it is never expressed in grams, since this is extremely inconvenient. For example, the mass of an atom of uranium, the heaviest element existing on Earth, is only 3.952 10 –22 d. Therefore, the mass of atoms is expressed in relative units, showing how many times the mass of atoms of a given element is greater than the mass of atoms of another element accepted as a standard. In fact, this is Dalton’s “weight ratio,” i.e. relative atomic mass. The masses of atoms are very small.

Absolute masses of some atoms:

m(C) =1.99268 ∙ 10 -23 g

m(H) =1.67375 ∙ 10 -24 g

m(O) =2.656812 ∙ 10 -23 g

Currently, a unified measurement system has been adopted in physics and chemistry. Introduced atomic mass unit (a.m.u.)

m(amu) = 1/12 m(12C) = 1.66057 ∙ 10 -24 g.

Ar(H) = m(atom) / m (a.m.u.) = 1.67375 ∙ 10 -24 g/1.66057 ∙ 10 -24 g = 1.0079 a.m.u.

Ar – shows how many times a given atom is heavier than 1/12 of a 12C atom; this is a dimensionless quantity.

Relative atomic mass is 1/12 of the mass of a carbon atom, whose mass is 12 amu.

Relative atomic mass is a dimensionless quantity!!!

For example, the relative atomic mass of the oxygen atom is 15.994. It is not always necessary to calculate the relative atomic mass values ​​yourself. You can use the values ​​​​given in the periodic table of chemical elements by D.I. Mendeleev. It should be written like this:

Ar(O) = 16 .

We always use the rounded value.

Exception represents the relative atomic mass of the chlorine atom: Ar(Cl) = 35.5.

The relationship between the absolute and relative masses of an atom is represented by the formula:

The prevalence of elements in nature. The bulk of cosmic matter consists of H and He (99.9%).

Of the 107 chemical elements, only 89 are found in nature, the rest, namely technetium (atomic number 43), promethium (atomic number 61), astatine (atomic number 85), francium (atomic number 87) and transuranium elements, are obtained artificially through nuclear reactions (tiny amounts of Te, Pm, Np, Fr are formed during the spontaneous fission of uranium and are present in uranium ores). In the accessible part of the Earth, the most common 10 elements with atomic numbers ranging from 8 to 26. In the earth's crust they are contained in the following relative quantities:

The listed 10 elements make up 99.92% of the mass of the earth's crust.

Chemistry, like any science, requires precision. The system for presenting data in this area of ​​knowledge has been developed over centuries, and the current standard today is an optimized structure containing all the necessary information for further theoretical work with each specific element.

When writing formulas and equations, it is extremely inconvenient to use integers, and today one or two letters are used for this purpose - the chemical symbols of the elements.

Story

In the ancient world, as well as in the Middle Ages, scientists used symbolic images to represent various elements, but these signs were not standardized. Only by the 13th century were attempts made to systematize the symbols of substances and elements, and from the 15th century, newly discovered metals began to be designated by the first letters of their names. A similar naming strategy is used in chemistry to this day.

Current state of the naming system

Today, more than one hundred and twenty chemical elements are known, some of which are extremely difficult to find in nature. It is not surprising that back in the middle of the 19th century, science knew about the existence of only 63 of them, and there was neither a single naming system nor an integral system for presenting chemical data.

The last problem was solved in the second half of the same century by the Russian scientist D.I. Mendeleev, relying on the unsuccessful attempts of his predecessors. The naming process continues today - there are several elements with numbers from 119 and higher, conventionally designated in the table by the Latin abbreviation of their serial number. The pronunciation of the symbols of chemical elements of this category is carried out according to the Latin rules for reading numerals: 119 - ununenniy (literally “one hundred and nineteenth”), 120 - unbiniliy (“one hundred and twentieth”) and so on.

Most of the elements have their own names, derived from Latin, Greek, Arabic, and German roots, in some cases reflecting the objective characteristics of substances, and in others acting as unmotivated symbols.

Etymology of some elements

As mentioned above, some names and symbols of chemical elements are based on objectively observable characteristics.

The name glow-in-the-dark phosphorus comes from the Greek phrase “to bring light.” When translated into Russian, quite a lot of “telling” names are revealed: chlorine - “greenish”, bromine - “foul-smelling”, rubidium - “dark red”, indium - “indigo-colored”. Since the chemical symbols of elements are given in Latin letters, the direct connection of the name with the substance for a Russian speaker usually goes unnoticed.

There are also more subtle naming associations. Thus, the name selenium comes from the Greek word meaning “Moon”. This happened because in nature this element is a satellite of tellurium, the name of which in Greek also means “Earth”.

Niobium is also named in a similar way. According to ancient Greek mythology, Niobe is the daughter of Tantalus. The chemical element tantalum was discovered earlier and its properties are similar to niobium - thus, the logical “father-daughter” connection was projected onto the “relationships” of chemical elements.

Moreover, it was not by chance that tantalum received its name in honor of a famous mythological character. The fact is that obtaining this element in its pure form was fraught with great difficulties, which is why scientists turned to the phraseological unit “Tantalum flour”.

Another interesting historical fact is that the name platinum literally translates as “silver,” i.e. something similar, but not as valuable, as silver. The reason is that this metal melts much more difficult than silver, and therefore did not find use for a long time and was not of particular value.

General principle for naming elements

When looking at the periodic table, the first thing that catches your eye is the names and symbols of the chemical elements. It is always one or two Latin letters, the first of which is capital. The choice of letters is determined by the Latin name of the element. Despite the fact that the roots of words come from ancient Greek, Latin, and other languages, according to the naming standard, Latin endings are added to them.

It is interesting that most of the symbols will be intuitive to a Russian speaker: aluminum, zinc, calcium or magnesium are easily remembered by a student the first time. The situation is more complicated with those names that differ in the Russian and Latin versions. It may take a long time for a student to remember that silicon is silicium and mercury is hydrargyrum. Nevertheless, you will have to remember this - the graphic representation of each element is oriented towards the Latin name of the substance, which will appear in chemical formulas and reactions as Si and Hg, respectively.

To remember such names, it is useful for students to do exercises like: “Match the symbol of a chemical element and its name.”

Other naming methods

The names of some elements originated from Arabic and were “stylized” into Latin. For example, sodium gets its name from a root stem meaning “bubbling matter.” Arabic roots can also be traced in the names of potassium and zirconium.

The German language also had its influence. From it come the names of such elements as manganese, cobalt, nickel, zinc, tungsten. The logical connection is not always obvious: for example, nickel is an abbreviation for the word meaning “copper devil.”

In rare cases, the names were translated into Russian in the form of tracing paper: hydrogenium (literally “giving birth to water”) turned into hydrogen, and carboneum into carbon.

Names and place names

More than a dozen elements are named after various scientists, including Albert Einstein, Dmitri Mendeleev, Enrico Fermi, Ernest Rutherford, Niels Bohr, Marie Curie and others.

Some names come from other proper names: names of cities, states, countries. For example: moscovium, dubnium, europium, tennessine. Not all toponyms will seem familiar to a native Russian speaker: it is unlikely that a person without cultural preparation will recognize in the word nihonium the self-name of Japan - Nihon (lit.: Land of the Rising Sun), and in hafnia - the Latin version of Copenhagen. Finding out even the name of your native country in the word ruthenium is not the easiest task. Nevertheless, Russia is called Ruthenia in Latin, and the 44th chemical element is named after it.

The names of cosmic bodies also appear in the periodic table: the planets Uranus, Neptune, Pluto, Ceres. In addition to the names of characters from ancient Greek mythology (Tantalum, Niobium), there are also Scandinavian ones: thorium, vanadium.

Periodic table

In the periodic table that is familiar to us today, named after Dmitry Ivanovich Mendeleev, the elements are presented in rows and periods. In each cell, a chemical element is designated by a chemical symbol, next to which other data is presented: its full name, serial number, distribution of electrons across layers, relative atomic mass. Each cell has its own color, which depends on whether the s-, p-, d- or f- element is highlighted.

Principles of recording

When writing isotopes and isobars, the mass number is placed at the top left of the element symbol - the total number of protons and neutrons in the nucleus. In this case, the atomic number, which is the number of protons, is placed on the lower left.

The charge of the ion is written on the top right, and on the same side below the number of atoms is indicated. Symbols for chemical elements always begin with a capital letter.

National recording options

The Asia-Pacific region has its own variants of writing the symbols for chemical elements, based on local writing methods. The Chinese notation system uses radical signs followed by characters in their phonetic meaning. Symbols for metals are preceded by the sign “metal” or “gold”, gases - with the radical “steam”, non-metals - with the hieroglyph “stone”.

In European countries there are also situations where the signs of elements when recorded differ from those recorded in international tables. For example, in France, nitrogen, tungsten and beryllium have their own names in the national language and are indicated by corresponding symbols.

Finally

When studying at school or even a higher educational institution, it is not at all necessary to memorize the contents of the entire periodic table. You should keep in mind the chemical symbols of the elements that are most often found in formulas and equations, and look up less commonly used ones from time to time on the Internet or in a textbook.

However, in order to avoid errors and confusion, you need to know how the data in the table is structured, in which source to find the required data, and clearly remember which element names differ in the Russian and Latin versions. Otherwise, you may accidentally mistake Mg for manganese and N for sodium.

To get practice at the initial stage, do the exercises. For example, provide the chemical element symbols for a random sequence of names from the periodic table. As you gain experience, everything will fall into place and the question of memorizing this basic information will disappear by itself.

The language of chemistry. Signs of chemical elements.

Chemical language and its parts

Humanity uses many different languages. In addition to natural languages ​​(Japanese, English, Russian - more than 2.5 thousand in total), there are also artificial languages, for example, Esperanto. Among artificial languages, languages ​​of various sciences stand out. So, chemistry uses its own chemical language. Chemical language is a system of symbols and concepts designed for a brief, succinct and visual recording and transmission of chemical information. A message written in most natural languages ​​is divided into sentences, sentences into words, and words into letters. If we call sentences, words and letters parts of language, then we can identify similar parts in chemical language (Table 1).

Table 1. Parts of chemical language

It is impossible to master any language immediately; this also applies to a chemical language. Therefore, for now you will only get acquainted with the basics of this language: learn some “letters”, learn to understand the meaning of “words” andproposals." You will become familiar with the names of chemical substances - an integral part of chemical language. As you study chemistry, your knowledge of chemical language will expand and deepen.

Chemical signs (chemical symbols) - letter designations of chemical elements. Consist of the first or the first and one of the following letters of the Latin name of the element, for example, carbon - C (Carboeum), calcium - Ca (Calcium), cadmium - Cd...

The symbol of a chemical element is a symbol for a chemical element.

Historical background: Chemists of the ancient world and the Middle Ages used symbolic images, letter abbreviations, and combinations of both to designate substances, chemical operations and instruments. The seven metals of antiquity were depicted with astronomical signs of the seven celestial bodies: the Sun (☉, gold), the Moon (☽, silver), Jupiter (♃, tin), Venus (♀, copper), Saturn (♄, lead), Mercury (☿, mercury ), Mars (♁, iron). Metals discovered in the 15th-18th centuries - bismuth, zinc, cobalt - were designated by the first letters of their names. The sign for wine spirit (Latin spiritus vini) is made up of the letters S and V. The signs for strong vodka (Latin aqua fortis, nitric acid) and golden vodka (Latin aqua regis, aqua regia, a mixture of hydrochloric and nitric acids) are made up of the sign for waterÑ and capital letters F and R respectively. The glass sign (Latin vitrum) is formed from two letters V - straight and inverted.

Attempts to streamline ancient chemical signs continued until the end of the 18th century. At the beginning of the 19th century, the English chemist J. Dalton proposed denoting atoms of chemical elements with circles, inside which were placed dots, dashes, the initial letters of the English names of metals, etc. Dalton's chemical symbols became somewhat widespread in Great Britain and Western Europe, but were soon replaced by purely alphabetic ones signs that the Swedish chemist J. J. Berzelius proposed in 1814. The principles he expressed for composing chemical signs have remained valid to this day. In Russia, the first printed message about Berzelius's chemical signs was made in 1824 by the Moscow doctor I. Ya. Zatsepin.

Below is a table of the chemical symbols of some elements, their names, relative masses and pronunciation.

RELATIVE ATOMIC MASS

Historical background: During his lectures, the English scientist John Dalton (1766–1844) showed students models of atoms carved from wood, showing how they could combine to form various substances. When one of the students was asked what atoms are, he replied: “Atoms are colored wooden blocks that Mr. Dalton invented.”

Of course, Dalton became famous not for his abs or even for becoming a school teacher at the age of twelve. The emergence of modern atomic theory is associated with the name of Dalton. For the first time in the history of science, he thought about the possibility of measuring the masses of atoms and proposed specific methods for this. It is clear that it is impossible to weigh atoms directly. Dalton talked only about “the ratio of the weights of the smallest particles of gaseous and other bodies,” that is, about their relative masses. And to this day, although the mass of any atom is known exactly, it is never expressed in grams, since this is extremely inconvenient. For example, the mass of an atom of uranium, the heaviest element existing on Earth, is only 3.952·10–22 g. Therefore, the mass of atoms is expressed in relative units, showing how many times the mass of atoms of a given element is greater than the mass of atoms of another element, accepted as a standard . In fact, this is Dalton’s “weight ratio,” i.e. relative atomic mass.

· The masses of atoms are very small.

Absolute masses of some atoms:

M(C) =1.99268 ∙ 10-23 g

M(H) =1.67375 ∙ 10-24 g

M(O) =2.656812 ∙ 10-23 g

· Currently, a unified measurement system has been adopted in physics and chemistry.

Introduced atomic mass unit (a.m.u.)

m(amu) = 1/12 m(12C) = 1.66057 ∙ 10-24 g.

· Ar(H) = m(atom) / m (amu) =

1.67375 ∙ 10-24 g/1.66057 ∙ 10-24 g = 1.0079 a.m.u.

· Ar – shows how many times a given atom is heavier than 1/12 of a 12C atom; this is a dimensionless quantity.

Relative atomic mass is 1/12 of the mass of a carbon atom, whose mass is 12 amu.

Relative atomic mass dimensionless quantity

For example, the relative atomic mass of the oxygen atom is 15.994 (we use the value from the periodic table of chemical elements by D.I. Mendeleev).
It should be written like this, Ar(O) = 16. We always use the rounded value, the exception is the relative atomic mass of the chlorine atom:

The relationship between the absolute and relative masses of an atom is represented by the formula:

m(atom) = Ar ∙ 1.66 ∙ 10 -27 kg

TASKS TO REINFORM THE TOPIC

Using PSHE, make pairs of signs of chemical elements and the corresponding Russian names:
N, Ar, P, Al, S, Mg, Cr
Aluminum, sulfur, nitrogen, chromium, phosphorus, argon, magnesium
№2.

Using PSHE, determine the relative atomic masses of chemical elements with serial numbers: 80, 23, 9, 2

Characterize the chemical element – ​​O according to its position in the PSCE according to the plan:
Russian name
Serial number
Pronunciation
Relative atomic mass value
№4.

For example, Cr, remove one initial letter from the name “chrome” and get “rum”

Solve a new word that can be obtained if you remove the number of letters corresponding to the number of dots from the beginning or end of the name of a chemical element.

A) : . Pd:
B) . Sn.

№6.
"Chemical dictation"

When answering this question, your task is to write down the chemical signs (symbols) of the elements, the Russian names of which will be given below (when writing the answer, write the symbols separated by a comma and a space, for example, Ti, Co, Al):

Sulfur
Nitrogen
Hydrogen

Copper
Carbon
Potassium
Calcium
Phosphorus

Work with the Relative Atomic Masses simulator

Part I

1. Horizontally, D.I. Mendeleev’s table is divided into periods, which are divided into:
a) small, these are periods – 1, 2, 3;
b) large, these are periods - 4, 5, 6, 7.

2. Vertically, D.I. Mendeleev’s table is divided into groups, each of which is divided into:
a) main, or A group;
b) side, or In group.
Group IA is a group of alkali metals.
Group IIA is a group of alkaline earth metals.
Group VIIA is a group of halogens.
Group VIIIA is a group of noble or inert gases.

4. Analogies of the language of chemistry with the Russian language.

5. Complete the table “Names and symbols of chemical elements.”

6. Examples of names of chemical elements (indicate the chemical sign in brackets) in accordance with etymological sources.

1) Properties of simple substances
Hydrogen (H), oxygen (O), fluorine (F)
2) Astronomy
Selenium (Se), tellurium (Te), uranium (U)
3) Geography
Germanium (Ge), gallium (Ga), polonium (Po)
4) Ancient Greek myths
Tantalum (Ta), promethium (Pm), lutetium (Lu)
5) Great scientists
Mendelevium (Md), rutherfordium (Rt), einsteinium (Es)

Part II

1. Establish a correspondence between the position of a chemical element in D.I. Mendeleev’s Periodic Table and the chemical sign.

A - 5; B - 1; AT 2; G – 4

2. Select symbols or names of chemical elements from one large period. Using the letters corresponding to the correct answers, you will form the name of the metal that is used to make sparklers: magnesium.

1) potassium M
2) Br A
5) manganese G
6) Cu H
8) Ca And
9)Zn

3. Write the names of the following chemical elements in the appropriate columns:
Cl, He, Br, Ne, Li, I, K, Ba, Ca, Na, Xe, Sr.

4. Fill in the blanks in the logic diagram.
Chemical element (H, O) → chemical reaction (H₂O) → chemical production (2 H₂O = 2 H₂ + O₂).

5. Make a generalization:
chemical elements - carbon, silicon, tin, lead - belong to group IVA.

6. In the left column of the table, write down on what basis the chemical elements are divided into two groups.

7. Establish a correspondence between the pronunciation and the chemical sign (symbol).

A – 3; B – 6; AT 2; G – 7; D – 5; E – 1.

8. Cross out the “extra”:

Curium, mendelevium, bromine, einsteinium.

9. General etymological source of names of chemical elements:

U, Te, Se is a planetarium.

10. Elements are named after various states or parts of the world:

Germanium, gallium, francium, dubnium.

Municipal state educational institution

"Popovo-Lezhachanskaya secondary school"

Regional seminar for chemistry teachers

Glushkovsky district, Kursk region

Open lesson in chemistry in 8th grade on the topic: “Signs of chemical elements”

Prepared by:

Kondratenko Olga Vasilievna,

teacher of chemistry and biology

MCOU "Popovo-Lezhachanskaya" secondary school

Glushkovsky district, Kursk region

Popovo-Lezhachi village

Chemistry, 8th grade

Date: 09/29/2015

Lesson #12

Subject:Chemical element signs

Target: consolidate the knowledge and skills of students on the topics “Methods of knowledge in chemistry”, “Pure substances and mixtures”, “Chemical elements”, “Relative atomic mass of chemical elements”.

Lesson objectives:

Educationals:

1. test students' knowledge and skills on topics“Methods of knowledge in chemistry”, “Pure substances and mixtures”, “Chemical elements”, “Relative atomic mass of chemical elements”using interactive learning tools;
2. summarize students’ knowledge on the topics studied;
3. identify gaps in mastering educational material.

Educational:

1. develop chemical language, logical thinking, attention, memory, interest in modern chemical science, student curiosity, the ability to draw conclusions and generalizations;
2. develop the skill of working with various sources of information in order to search and select the necessary material.

Educational:

1. to form positive motivation for educational activities and a scientific worldview;
2. develop a culture of mental work; skills of business cooperation in the process of problem solving, working in groups;
3. cultivate the ability to work in a team, politeness, discipline, accuracy, hard work;
4. develop the ability to formulate and argue your own opinion, independence.

Planned results:

personal: students' readiness and ability for self-development and self-determination; responsible attitude to learning; the ability to set goals and make life plans; formation of a communicative culture, the values ​​of a healthy and safe lifestyle;

meta-subject: be able to set a goal and plan ways to achieve it, choosing more rational ways to solve a given problem; learn to adjust your actions in connection with changes in the current situation; be able to create, apply and transform signs and symbols, models and diagrams to solve educational and cognitive problems; be able to consciously use verbal means in accordance with the task of communication to express their thoughts and needs; be able to organize joint work with peers in a group; be able to find information in various sources; possess the skills of self-control and self-esteem;

subject:

know: basic chemical concepts “chemical element”, “simple substance”, “complex substance”, signs of basic chemical elements; composition of simple and complex substances; the role of chemistry in human life and in solving environmental problems;

be able to: use the formula to distinguish a simple substance from a complex one; distinguish a chemical element from a simple substance; analyze and objectively evaluate skills in safe handling of substances; establish connections between actually observed chemical phenomena and processes occurring in the microcosm; use various methods for studying substances.

Lesson type: knowledge control.

Forms of work: group, work in pairs, play.

Teaching methods: problematic presentation, partially search-based.

Teaching Techniques: posing problematic issues.

Means of education: computer, projector, Power Point presentation

Equipment for teachers and students: computer, projector, periodic table of chemical elements, laboratory stand, ring, porcelain cup, alcohol lamp, filter paper, scissors, beakers, glass rod, contaminated salt mixture, water.

Literature:

For the teacher:

1. Gorkovenko M. Yu. Lesson developments in chemistry, grade 8, for textbooks by O. S. Gabrielyan, L. S. Guzei, G. E. Rudzitis. - M: “VAKO”, 2004;
2. Radetsky A. M., Gorshkova V. P. Didactic material: chemistry grades 8-9 - M: Prosveshchenie, 1997.

For the student:

Chemistry: inorganic chemistry: textbook for the 8th grade of general education institutions / G. E. Rudzitis, F. G. Feldman. - M: “Enlightenment”, 2014

During the classes:

I.Organizational moment (1 min)

Teacher: Good afternoon I ask everyone to sit down. I congratulate you on another wonderful day. And you and I continue to create magic in chemistry lessons.

II.Motivation for learning activities (1 min)

Teacher: Today we have an unusual lesson. It will take the form of a game. The score of your work at the end of the lesson will be higher, the more points you score. The number of tasks and their type are selected in such a way that you can earn more than 40 points for completing the work. You will receive a grade according to the conversion charts located on your desks.

III.Control and correction of knowledge

1. Attention, question! (10 min)

Teacher: Explain the etymology of the names of chemical elements.

Student: The names of the elements have different etymologies. They come from:

names of countries and continents - for example, the name ruthenium comes from the Latin name of Russia, and the names europium and americium come from the names of the continents: Europe and America;

the names of outstanding chemists - for example: mendelevium, nobelium, rutherfordium;

names of planets - for example: uranium, neptunium, plutonium;

names of rivers - for example, rhenium.

All known elements have symbols. The symbolic designation of elements was proposed in 1814 by J. J. Berzelius. Previously, various abbreviations for elements and connections were also used. One of these types of designations were graphic symbols.

Teacher: What do we know from the history of the development of the language of chemistry?

Student: Back in the Middle Ages, during the time of alchemy, various signs were used to designate substances, mainly metals. After all, the main goal of alchemists was to obtain gold from various metals. Therefore, each of them used their own notation system. In the 19th century There was a need to use symbols that were understandable to all scientists. And John Dalton was one of the first to propose such symbolism. But his notation was inconvenient to use.

Teacher: Tell us about the system of designation of chemical elements by Y.Ya. Berzelius

Student: The modern system of chemical signs was proposed at the beginning of the 19th century. Swedish chemist Jons Jakob Berzelius. The scientist proposed to designate chemical elements by the first letter of their Latin name. In those days, all scientific articles were published in Latin; it was generally accepted and understandable for all scientists. For example, the chemical element oxygen (in Latin Oxygenium) received the designation O. And the chemical element hydrogen (Hydrogenium) - H. If the names of several elements began with the same letter, then the second or one of the subsequent letters of the name was indicated in the symbol of the element. For example, mercury (Hydrargyrum) is designated Hg. Please note that the first letter of the symbol of a chemical element is always capitalized; if there is a second letter, then it is lowercase. It is necessary to remember not only the names of the elements and their symbols, but also the pronunciation, i.e. how these characters are read. There are no specific rules for pronunciating the signs of chemical elements. They must be learned by heart. The signs of some chemical elements are pronounced in the same way as the corresponding letter: oxygen - “o”, sulfur - “es”, phosphorus - “pe”, nitrogen - “en”, carbon - “ce”. The signs of other elements are pronounced in the same way as the names of the elements themselves: “sodium”, “potassium”, “chlorine”, “fluorine”. The pronunciation of some signs corresponds to their Latin name: silicon - “silicium”, mercury - “hydrargyrum”, copper - “cuprum”, iron - “ferrum”.

Teacher: What is the meaning of the symbols of chemical elements?

Student: The sign of a chemical element has several meanings. Firstly, it refers to all the atoms of a given element. Secondly, the sign of a chemical element can designate one or more atoms of a given element. For example, the entry O can mean "the chemical element oxygen" or "one atom of oxygen."

To designate several atoms of a given chemical element, you need to put a number corresponding to the number of atoms in front of its sign. For example, the notation 3N means “three nitrogen atoms.” The number preceding the sign of a chemical element is called a coefficient.

Student: Attempts to streamline ancient chemical signs continued until the end of the 18th century. At the beginning of the 19th century, the English chemist J. Dalton proposed denoting atoms of chemical elements with circles, inside which were placed dots, dashes, the initial letters of the English names of metals, etc. Dalton's chemical symbols became somewhat widespread in Great Britain and Western Europe, but were soon replaced by purely alphabetic ones signs that the Swedish chemist J. J. Berzelius proposed in 1814. The principles he expressed for composing chemical signs have remained valid to this day. In Russia, the first printed message about Berzelius's chemical signs was made in 1824 by the Moscow doctor I. Ya. Zatsepin.

Teacher: What are the designation principles?

Student: Modern symbols for chemical elements consist of the first letter or the first and one of the following letters of the Latin name of the elements. In this case, only the first letter is capitalized. For example, H - hydrogen (lat. Hydrogenium), N - nitrogen (lat. Nitrogenium), Ca - calcium (lat. Calcium), Pt - platinum (lat. Platinum), etc. For newly discovered transuranic elements that are not yet received a name approved by IUPAC, they use three-letter designations meaning a numeral - a serial number. For example, Uut - ununtrium (lat. Ununtrium, 113), Uuh - unungexium (lat. Ununhexium, 116). Hydrogen isotopes have special symbols and names: H - protium 1H, D - deuterium 2H, T - tritium 3H. To designate isobars and isotopes, the symbol of a chemical element is preceded by a mass number at the top (for example, 14N), and at the bottom left is the element's atomic number (for example, 64Gd). In the case where the mass number and atomic number are not indicated in chemical formulas and chemical equations, each chemical symbol expresses the average relative atomic mass of its isotopes in the earth's crust. To indicate a charged atom, the charge of the ion (eg Ca2+) is indicated at the top right. The number of atoms of a given element in a real or conditional molecule (for example, N2 or Fe2O3) is indicated at the bottom right. Free radicals are indicated by a dot on the right (eg Cl·).

Student: Chemists of the ancient world and the Middle Ages used symbolic images, letter abbreviations, and combinations of both to denote substances, chemical operations and instruments. The seven metals of antiquity were depicted with astronomical signs of the seven celestial bodies: the Sun (gold), the Moon (☽, silver), Jupiter (♃, tin), Venus (♀, copper), Saturn (♄, lead), Mercury (☿, mercury) ,Mars (♁, iron). Metals discovered in the 15th-18th centuries - bismuth, zinc, cobalt - were designated by the first letters of their names. The sign for wine spirit (Latin spiritus vini) is made up of the letters S and V. The signs for strong vodka (Latin aqua fortis, nitric acid) and golden vodka (Latin aqua regis, aqua regia, a mixture of hydrochloric and nitric acids) are made up of the sign for water Ñ ​​and capital letters F and R respectively. The glass sign (Latin vitrum) is formed from two letters V - straight and inverted.

Teacher: Tell us about international and national symbols.

Student: The symbols given in the Periodic Table of Elements are international, but along with them, in some countries, symbols derived from the national names of the elements are used. For example, in France, instead of the symbols for nitrogen N, beryllium Be and tungsten W, Az (Azote), Gl (Glucinium) and Tu (Tungstène) can be used. In the USA, Cb (Columbium) is often used instead of the niobium symbol Nb. China uses its own version of chemical signs, based on Chinese symbols. Most symbols were invented in the 19th and 20th centuries. Symbols for metals (except mercury) use the radical or ("gold", metal in general), for non-metals that are solid under normal conditions - the radical ("stone"), for liquids - ("water"), for gases - ("steam") . For example, the symbol for molybdenum consists of a radical and a phonetic that specifies the pronunciation mu4.

Physical education minute (1 min)

2. Game “Flower-seven-flowered” (7 points)(2 minutes.)

Inscribe in each petal of a seven-flowered flower physical bodies or substances (according to options) that must be selected from a specific list.

Nail, zinc, vase, hammer, iron, table salt, spoon, magnesium, gold, water, ice floe, apple, pencil, glass.

Physical bodies Substances

Answers:

Bodies: nail, vase, hammer, spoon, ice floe, apple, pencil.

Substances: zinc, iron, table salt, magnesium, gold, water, glass.

3. Tic-tac-toe game (3 points) (1 min)

Find the winning path in the tables:

Ioption- homogeneous mixtures;

IIoption- heterogeneous mixtures.

Answer:

The top line is homogeneous mixtures;

The bottom line is heterogeneous mixtures.

4. Competition “Young Chemists” (15 points, 1 point for each correct answer) (2 min)

Which team can name the most safety rules in the chemistry classroom?

5. Competition “Divide me” (4 points), 1 point for the correct answer) (3 min)

Match the mixture with the method by which it can be separated into pure substances.

Answer:

Ioption

IIoption

6. Competition"Associations".(9 points)(2 minutes)

Participants must name laboratory equipment that, by function, appearance or name, is associated with the object shown in the picture;

7. Competition “I’m a master of inventions” (7 points, 1 point per element). (1 min)

Name as many chemical elements as possible using the letters of the term "Tungsten".

Answer: vanadium, osmium, lithium, francium, rhodium, aluminum, magnesium.

8. Competition “Parade of Chemical Elements” (3 points). (1 min)

Fill out the table.

Answer:

10 . Competition "Pyramid" (3 points) (2 min)

Make a pyramid of chemical elements based on their atomic masses.

Answer:

11. Competition “Terms”. (12 points, 1 point for correct answer) (2 min)

The teacher dictates the names of chemical elements, and students write them down with symbols on the board.

Answer:

N, Na, Ba, Ca, H, O, C, Al, Mg, K, Cl, F.

12. Competition “Last Chance” (10 points, 1 point for correct answer) (2 min)

Teams take turns answering questions without repeating themselves. The last one to answer wins. Translate the following expressions from chemical language into conventional language:

Not all that glitters is aurum. (All that glitters is not gold).

White, like calcium carbonate. (White as chalk).

Ferrum character. (Iron character).

The word is argentum, and silence is aurum. (The word is silver and silence is gold).

A lot of money has leaked. (A lot of water has passed under the bridge).

Which element is always happy. (Radon).

Which gas claims that it is not it? (Neon).

Which element “orbits” the Sun? (Uranus).

Which element is a real “giant” (Titanium).

Which element is named after Russia? (Ruthenium).

IV. Psummarizing. (1 min.)

Teacher: All this time, over the course of twelve lessons, you and I have been trying to open the symbolic door and enter the interesting country called chemistry. We were able to open it a little and see what was behind it. It’s interesting there, there’s a lot of unknowns that attract us. Now we will decide whether you are ready for the serious tests that await us. Let's find out whether you have enough knowledge for this, whether you have mastered these topics well. Yes, not just learned, but which of you did it better.

(Announcement of grades by points)

V.Homework(1 min)

§12, No. 1-4 p.44. Creative task: make a chemical crossword puzzle.

VI.Reflection(1 min)

Today I found out...

it was difficult…

I realized that...

I learned…

It was interesting to know that...

I was surprised...