Municipal state educational institution

"Popovo-Lezhachany secondary school"

District Seminar for Chemistry Teachers

Glushkovsky district, Kursk region

Open lesson in chemistry in grade 8 on the topic: "Signs chemical elements»

Prepared by:

Kondratenko Olga Vasilievna,

chemistry and biology teacher

MKOU "Popovo-Lezhachanskaya" secondary school

Glushkovsky district, Kursk region

s.Popovo-Lyozhachi

Chemistry, grade 8

Date: 29.09.2015

Lesson #12

Topic:Signs of chemical elements

Target: to 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 the knowledge and skills of students on topics"Methods of knowledge in chemistry", "Pure substances and mixtures", "Chemical elements", "Relative atomic mass of chemical elements"using interactive learning tools;
2. generalize students' knowledge on the topics studied;
3. identify gaps in the assimilation of educational material.

Developing:

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

Educational:

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

Planned results:

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

metasubject: be able to set a goal and plan ways to achieve it, choosing more rational ways to solve this problem; learn to adjust their actions in connection with a change in the situation; be able to create, apply and transform signs and symbols, models and schemes for solving educational and cognitive problems; be able to consciously use speech 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, self-assessment;

subject:

know: main 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: by the formula to distinguish a simple substance from a complex one; distinguish a chemical element from a simple substance; analyze and objectively assess skills for the safe handling of substances; establish links between real-life chemical phenomena and processes taking place in the microcosm; use various methods of studying substances.

Lesson type: knowledge control.

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

Teaching methods: problem presentation, partially exploratory.

learning techniques: posing problem questions.

Means of education: computer, projector, Power Point presentation

Equipment for teacher and students: computer, projector, "Periodic Table of Chemical Elements", laboratory tripod, ring, porcelain cup, spirit lamp, filter paper, scissors, chemical beakers, glass rod, contaminated salt mixture, water.

Literature:

For the teacher:

1. Gorkovenko M. Yu. Lesson developments in chemistry grade 8 for the textbooks of O. S. Gabrielyan, L. S. Guzey, G. E. Rudzitis. - M: "VAKO", 2004;
2. Radetsky A. M., Gorshkova V. P. Didactic material: chemistry grades 8-9 - M: Education, 1997.

For a student:

Chemistry: inorganic chemistry: textbook for grade 8 educational 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 we 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 grade of your work at the end of the lesson will be the 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 an assessment according to the conversion schemes that are on your desks.

III.Control and correction of knowledge

1. Attention, question! (10 min)

Teacher: Describe 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 of europium and americium come from the names of the continents: Europe and America;

surnames of prominent chemists - for example: mendelevium, nobelium, rutherfordium;

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

river names - for example, rhenium.

All known elements have symbols. The symbolic designation of the elements was proposed in 1814 by J. J. Berzelius. Previously, various abbreviations for elements and compounds were also used. One of these types of symbols 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 days 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. In the 19th century there was a need to use symbolism understandable to all scientists. And one of the first such symbols was proposed by John Dalton. 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 in early XIX in. Swedish chemist Jöns Jakob Berzelius. The scientist suggested designating chemical elements by the first letter of their Latin name. In those days, all scientific articles were printed on Latin, it was generally accepted and understood by 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 element symbol. For example, mercury (Hydrargyrum) is designated Hg. Please note that the first letter of the sign of a chemical element is always capitalized, if there is a second letter, then it is lowercase. It is necessary to memorize 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 pronouncing 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 elements themselves are called: “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 signs of chemical elements?

Student: The sign of a chemical element has several meanings. First, 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 notation O can mean: "the chemical element oxygen" or "one oxygen atom".

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

Student: Attempts to streamline the ancient chemical signs continued until the end of the 18th century. At the beginning of the 19th century, the English chemist J. Dalton proposed to designate the atoms of chemical elements by circles, inside which were placed dots, dashes, the initial letters of the English names of metals, etc. Dalton's chemical signs became somewhat widespread in Great Britain and in Western Europe, but were soon superseded by purely alphabetic signs, which the Swedish chemist J. Ya. Berzelius proposed in 1814. The principles he expressed for compiling chemical signs have retained their force to this day. In Russia, the first printed report on the chemical signs of Berzelius was made in 1824 by the Moscow physician I. Ya. Zatsepin.

Teacher: What are the design principles?

Student: Modern symbols for chemical elements consist of the first letter or of the first and one of the following letters of the Latin name of the elements. However, only the first letter is capitalized. For example, H is hydrogen (lat. Hydrogenium), N is nitrogen (lat. Nitrogenium), Ca is calcium (lat. Calcium), Pt is platinum (lat. Platinum), etc. For newly discovered transuranic elements that have not yet have received an IUPAC-approved name, use three-letter designations, meaning a numeral - a serial number. For example, Uut is ununtrium (lat. Ununtrium, 113), Uuh is 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 the chemical element at the top is preceded by mass number(e.g., 14N), and at the bottom left - the serial number of the element (atomic number) (e.g., 64Gd). In the case when in chemical formulas and chemical equations the mass number and serial number are not indicated, each chemical sign 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. At the bottom right, the number of atoms of a given element in a real or conditional molecule (eg, N2 or Fe2O3) is indicated. Free radicals are indicated by a dot on the right (eg Cl·).

Student: Chemists ancient world and the Middle Ages, symbolic images, letter abbreviations, as well as combinations of both, were used to designate substances, chemical operations and devices. The seven metals of antiquity were depicted as astronomical signs of the seven heavenly bodies: the Sun (☽, silver), Jupiter (♃, tin), Venus (♀, copper), Saturn (♄, lead), Mercury (☿, mercury) , Mars (♁ , iron). The metals discovered in the 15th-18th centuries - bismuth, zinc, cobalt - were designated by the first letters of their names. The sign of wine spirit (lat. spiritus vini) is made up of the letters S and V. The signs of strong vodka (lat. aqua fortis, nitric acid) and golden vodka (lat. aqua regis, aqua regia, a mixture of hydrochloric and nitric acids) are made up of the sign of water Ñ ​​and capital letters F and R, respectively. The sign of glass (lat. 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 the Elements are international, but along with them, in some countries, designations derived from the national names of the elements are commonly used. For example, in France, Az (Azote), Gl (Glucinium), and Tu (Tungstène) may be used instead of nitrogen N, beryllium Be, and tungsten W. In the United States, Cb (Columbium) is often used instead of Nb for niobium. China uses its own version of chemical signs based on Chinese characters. Most of the symbols were invented in the 19th and 20th centuries. Symbols for metals (except mercury) use a radical or ("gold", metal in general), for non-metals that are solid under normal conditions - a 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 of mu4.

Physical education (1 min)

2. The game "Flower-Semitsvetik" (7 points)(2 minutes.)

Inscribe in each petal of a semi-flower physical bodies or substances (by options), which must be selected from a specific list.

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

Physical bodies Substances

Answers:

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

Substances: zinc, iron, 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- inhomogeneous mixtures.

Answer:

Top line - homogeneous mixtures;

The bottom line is heterogeneous mixtures.

4. Competition "Young chemists" (15 points, 1 point for each correct answer) (2 min)

Which of the teams will name the safety rules in the chemistry classroom more.

5. Competition "Undress 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 are asked to name laboratory equipment that, by function, appearance or the name is associated with the object depicted in the figure;

7. Competition "I'm a fan of fiction" (7 points, 1 point per element). (1 minute)

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 minute)

Fill in the table.

Answer:

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

Make a pyramid of chemical elements according to their atomic masses.

Answer:

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

The teacher dictates the names of chemical elements, the students write them down on the blackboard.

Answer:

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

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

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

Not everything is aurum that glitters. (Not all that glitters is gold.)

White like calcium carbonate. (White as chalk).

Ferrum character. (Iron character).

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

A lot of ash two o flowed away. (A lot of water has flowed under the bridge).

Which element is always happy. (Radon).

Which gas claims to be not it? (Neon).

Which element "revolves" around the sun? (Uranus).

Which element is the real "giant" (Titanium).

What element is named after Russia? (Ruthenium).

IV. Psummarizing. (1 minute.)

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

(Announcement of grades by points)

v.Homework(1 minute)

§12, #1-4 p.44. Creative task: make a chemical crossword puzzle.

VI.Reflection(1 minute)

Today I found out...

it was difficult…

I realized that...

I learned…

It was interesting to know that...

surprised me...

The language of chemistry. Signs of chemical elements.

Chemical language and its parts

Humanity uses a lot 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, the languages ​​of various sciences stand out. So, chemistry uses its own, chemical language. Chemical language is a system of symbols and concepts designed for concise, concise 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 the language, then we can distinguish similar parts in the chemical language (Table 1).

Table 1. Parts of the chemical language

It is impossible to master any language at once, this also applies to the 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" and "sentences". You will get acquainted with the names of chemicals - an integral part of the chemical language. As you study chemistry, your knowledge of the chemical language will expand and deepen.

Chemical signs (chemical symbols) - letter designations of chemical elements. They 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 of a chemical element.

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

Attempts to streamline the ancient chemical signs continued until the end of the 18th century. At the beginning of the 19th century, the English chemist J. Dalton proposed to designate the 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 signs gained some distribution in Great Britain and Western Europe, but were soon supplanted by purely alphabetic signs that the Swedish chemist J. Ya. Berzelius proposed in 1814. The principles he expressed for compiling chemical signs have retained their force to this day. In Russia, the first printed report on the chemical signs of Berzelius was made in 1824 by the Moscow physician I. Ya. Zatsepin.

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

RELATIVE ATOMIC MASS

Historical note: The English scientist John Dalton (1766–1844) in his lectures showed students models of atoms carved from wood, showing how they can combine to form various substances. When one of the students was asked what atoms were, he replied: "Atoms are wooden cubes painted in different colors, which Mr. Dalton invented."

Of course, Dalton became famous not for his "cubes" and not even for the fact that at the age of twelve he became a school teacher. The emergence of modern atomistic 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 directly weigh the atoms. Dalton talked only about "the ratio of the weights of the smallest particles of gaseous and other bodies", that is, about their relative masses. Even today, although the mass of any atom is known exactly, it is never expressed in grams, as this is extremely inconvenient. For example, the mass of an atom of uranium, the heaviest of the elements 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 taken as a standard . In fact, this is the “weight ratio” according to Dalton, 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) \u003d 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(a.m.u.) = 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 amu

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 an oxygen atom is 15.994 (we use the value from the periodic system of chemical elements of 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:

Relationship between absolute and relative masses atom is represented by the formula:

m (atom) \u003d Ar ∙ 1.66 ∙ 10 -27 kg

TASKS FOR REINFORCING THE THEME

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

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

Give a characteristic of the chemical element - O according to its position in the PSCE according to the plan:
Russian name
Serial number
Pronunciation
Relative value atomic mass
№4.

For example, Cr , we remove one initial letter from the name "chrome" and get "rum"

Guess a new word that can be obtained if the number of letters corresponding to the number of dots is removed from the beginning or end of the name of a chemical element.

BUT) : . 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 down the symbols separated by commas and spaces, for example, Ti, Co, Al):

Sulfur
Nitrogen
Hydrogen

Copper
Carbon
Potassium
Calcium
Phosphorus

Work with the simulator "Relative atomic masses"