Target: generalize and systematize knowledge about simple and complex substances, calculate the relative molecular masses of substances, draw up chemical formulas of binary compounds by valency and determine valence by formula, equalize chemical equations;
to develop the creative and cognitive activity of students, the ability to compare, analyze, find solutions in non-standard situations;
continue to form interest in chemical science, using interdisciplinary material, the ability to work in pairs, groups.
^ Lesson type: generalization and systematization of knowledge.
Equipment: presentation (there are blank slides in the presentation so as not to distract students from working with the image on the screen)
^ Lesson progress:
Organizational moment (checking absentees)
Actualization of cognitive activity:
What topic did we study?
Today we will summarize our knowledge….
So, we will write down our homework: repeat the main terms of the topic, paragraph ...
^ Repetition and generalization of the studied material
Guys, you know that one of the participants in your class, as always, received textbooks in the month of August. Having opened the textbook of chemistry, between the pages of the textbook I found a suspicious note... Message from the alchemist. What is written there?
"Dear friend! Do you want to find treasure? What is needed for this? Your ingenuity and my support. If you have it, then go! I'm sending you a map and instructions."
First, let's fill out the itinerary sheets. Open a notebook, write down the number, class work. But before we set off, we must check whether everyone is ready for this test, check our knowledge base. Only those who score at least 4 points will go on the road.
Chemical dictation (mutual check)
The science of substances and their properties (chemistry)
What is the name of the type of atom with a certain nuclear charge (chemical element)
What are the names of substances consisting of one type of chemical elements (simple)
What is the name of the scientist who discovered the periodic law and the periodic table of chemical elements (D.I. Mendeleev)
Conditional notation of an atom, molecule, ion or substance using chemical elements and indices (chemical formula)
What two types of mixtures do you know (homogeneous and heterogeneous)
Name three methods for separating heterogeneous mixtures. (settling, filtering, magnet action)
What is the name of the phenomenon in which a substance does not change into another (physical)
This scientist discovered the law of conservation of mass of matter. (M.V. Lomonosov)
What method can be used to separate a mixture of wood and iron filings (magnet action)
What laboratory equipment is used to heat a test tube over an alcohol lamp? (tube holder)
What laboratory glassware can be used to measure a certain volume of water (measuring cylinder). MUTUAL CHECK Are there any students who have 1b, 2b, 3b? The baggage of knowledge is different, but we all hit the road. Let's repeat the rules of safe movement.
Starting from the top left cell, and moving horizontally (left or right) or vertically (up or down), go through all the cells in such a way that the letters given in the cells form a rule for precautionary measures when handling chemical reagents. Each letter can only be used once.
| X | and | R | e | a | to | P | R | about | b | about | at | With |
| and | m | e | and | and | t | I | h | b | a | in | to | in |
| h | e | With | to | in | s | n | e | l | t | b | n | a |
Chemical reagents cannot be tasted
So let's go on a treasure hunt. Our path is not easy. We have many obstacles, and the first one is to choose the right direction. After completing the task, we will find the right path. In the task, it is necessary to find non-metal elements that are in the same line or vertical or horizontal.
^ Right way
Answer: 1) N.C.O
That's right, we found the right way.
Guys, let's split into groups
And here is our first hurdle Cryptographer
^
Each team is given a playing field on which the formulas of simple and complex substances are written.
| BUT | B | AT | G | D |
|
| 1 | KOH | FROM | Zpo | O 2 | SO 3 |
| 2 | СuО | Ca 3 P 2 | H 2 CO 3 | Fe | N 2 O |
| 3 | LiH | N2 | S | H 2 0 | Cu |
| 4 | R | Na 2 O | MgBr 2 | H 2 | A1C1 3 |
| 5 | HNO 3 | Cr 2 O 3 | C1 2 | AgCI | Si |
The teacher gives the coordinates to the first team: the student who answers must read the formula and say a simple or complex substance. This formula is crossed out, and the student calls the new coordinates to the students of the other team. Correct answer - point, incorrect answer - the move goes to the other team
Well done! We divided substances into simple and complex. Let's continue our journey.
Oh what happened here? The crook mixed up some elements in the periodic table, we need to return them back.
^ Find element
According to the position of the element in the periodic system, name it, why and why it is necessary for the human body, in our life.
The element is in period 4, group 2 (calcium)
The element has the atomic number 8 (oxygen)
An element whose atomic mass is 35.5 (chlorine)
Non-metal element, located in period 5, group 7 (iodine)
An element whose atomic mass is 48 (titanium)
The element is in period 6 with an atomic mass of 197 (aurum)
Metal element, located in the 4th period, 8th group (ferrum)
Write down the formulas of substances that have the following composition:
a) two water molecules;
b) 2 Phosphorus and 5 Oxygen atoms;
c) 1 atom of Phosphorus, 3 atoms of Hydrogen;
e) 1 silicon atom, 2 oxygen atoms;
f) 2 Chromium atoms, 3 Oxygen atoms;
g) 1 hydrogen atom, 1 nitrogen atom, 3 oxygen atoms.
f) 2 Sodium atoms, 1 Sulfur atom and 4 Oxygen atoms
Before us stretched a huge forest. And Little Red Riding Hood knows the way through the forest, who carries pies to her beloved grandmother. The safest way is where the sum of the relative molecular weights will be the smallest. (see presentation 25 slide)
PHYSMINUTKA
^ Our lesson is running forward
Are our people healthy?
We all rise together, we start the step in place.
We raise our hands to the sun, we wish everyone good health.
^ Hands up and hands down
Everyone gathered their thoughts.
Quietly sat down do not yawn
And we continue to work.
The road through the forest led us to the river.
It is difficult to overcome the river, because the river is saturated with insatiable piranhas - one careless movement and you risk falling into the water, where in a matter of minutes you will turn into a skeleton. How to be? There is a way out - the shore is full of huge boulders, along which it is easy to go to the other side. Each boulder is a correctly formulated formula of a substance or a definition of the valence of elements in a substance.
Determine the valency of elements in compounds:
SO 2, K 2 O, Cr 2 O 3 BaO FeO, SO 3, As 2 O 5
Knowing the valencies of the elements, make compound formulas
III II I III I II II II IV I III II I II
Al S, Na P, Ag O, Mg O, Si H, B O Na S
And here is the sea on our way, but in order to get to the long-awaited island, we need to complete the following task. I will read the chemical elements in a certain sequence, and you will combine them in a certain sequence. (by connecting the names of chemical elements, a boat should form)
We got a boat, so we'll sail on it. We are loading onto the ship.
There was a small emergency on the upper deck: physical and chemical phenomena mixed up. They need to be distributed in places according to the ordered tables.
^ frost formation,
rusting iron,
Soap bubble formation
Yellowing leaves
burning wood,
Creation of ice figures
Explosions of New Year's fireworks
The ship sailed to the island. We land on the ground.
We came to the highest gorge. Inhabited by poisonous snakes, there is a bridge across it, which is guarded by an evil giant. As soon as the traveler steps on the bridge, the giant begins to swing it, trying to throw the daredevil into the gorge. To avoid trouble, it is necessary to establish a balance in the equations of chemical reactions proposed by the giant
P + Cl 2 → PCl 5
Na + S → Na 2 S
H 2 O → H 2 + O 2
K + O 2 \u003d K 2 O;
Na 2 O + H 2 O \u003d NaOH;
Na + Cl 2 \u003d NaCl;
Al 2 O 3 + Fe = Fe 2 O 3 + Al;
To get the treasure, we have to solve this crossword
So, we have successfully completed all the tasks, which means that you have found the treasure, which is in the next message of the Alchemist
Dear friend! And now I will tell you a secret: the real treasure is the knowledge that you have obtained yourself!
Reflection
today I found out...
it was interesting…
it was difficult…
I did assignments...
I realized that...
Now I can…
I felt that...
I purchased...
I learned…
I managed …
I'll try…
surprised me...
gave me a lesson for life...
Lesson - travel
"Original Chemical Concepts"
The purpose of this lesson is to apply knowledge in practice.
Tasks:
educational: to teach how to apply the acquired knowledge in practice; operate with the available potential in a particular situation; to consolidate the skills and abilities of working with chemical glassware and reagents; learn to defend your point of view.
developing: to improve the skills of working with sources of knowledge; improve the skills of analysis, generalization; the ability to speak and defend one's point of view; develop creative abilities; develop communication skills in group work; develop a cognitive interest in the surrounding life.
educational: involve in vigorous activity; to form a culture, including an ecological one, to form the humane qualities of the personality of students; improve communication skills.
Lesson type: application of knowledge in practice
Stages: organizational, goal setting, updating knowledge, operating knowledge, skills and abilities in solving practical problems, compiling a report on the performance of work, determining homework
Equipment and reagents: periodic table of chemical elements, didactic material, laboratory tripod, porcelain cup, water in a flask, test tubes, heater, matches, solutions of perchloric acid, sulfate acid, barium chloride, sodium carbonate, candle.
Basic concepts and terms: simple and complex substances, valency, formula, chemical reaction, chemical reaction equation.
Methods and techniques: verbal: conversation, story; practical: problem solving.
DURING THE CLASSES
Organizational moment
Epigraph of the lesson: "The only way that leads to knowledge is activity"
B.Show
Announcement of the topic and purpose of the lesson.
Students are united in teams (crews), a leader is selected in the group - a captain, a boatswain, a radio operator, a pilot and a sailor (or cabin boy)
Teacher's word.
For half a year we have been studying the theoretical basics of chemical science. Today we will go on a sea voyage through the ocean of chemical knowledge. In swimming, all the knowledge and skills that you have acquired in the lessons will be useful to you. If you successfully pass this test, then each of you will receive a pass to the vast realm of chemicals, which will be discussed in subsequent chemistry lessons.
I ask captains to come to me and get waybills for their crew. In them you will mark the passed stages and the points received.
Main part
I. CUSTOMS
Game Decoder.
Each team must guess one of the key words of our lesson.
Molecule
Substance
Formula
Reaction
The pilot who helped lead the team to their port reports on the completion of the task. (1 point)
II.
What is a chemical formula?
How to correctly formulate a substance?
What is called valence?
Bosuns work on cards, formulate substances by valency. (3 points)
Captains check the correctness of the task. (1 point)
N(III)
O(II)
Cl(I)
Mg(II)
Al(III)
K(I)
R(III)
O(II)
F(I)
Mg(II)
Al(III)
K(I)
R(III)
O(II)
F(I)
Ca(II)
Fe(III)
Na(I)
N(III)
O(II)
Cl(I)
Ca(II)
Fe(III)
Na(I)
The rest of the crew members work with the periodic system.
(For the correct answer - a chip = 1 point)
Find, write down and name three elements that are named after cosmic bodies
Find, write down and name three elements that are named after great scientists
Find, write down and name three elements that are named after geographical features
III. Island of Changes
1) Any changes that occur around are calledphenomena .
What are the phenomena?
What is another word for chemical phenomena?
Name the signs of chemical reactions.
2) To continue the path, it is necessary to determine which of the named phenomena are physical and which are chemical. (Graphic dictation )
Mark chemical phenomena with a sign+ , and physical -
Iron rust(+)
Souring milk(+)
Freezing water(-)
Smelting Lead(-)
Dynamite Explosion(+)
Frost(-)
Dissolving sugar in water(-)
Leaf rot(+)
Twisting the wire into a spiral (-)
Grape juice fermentation(+)
Mutual verification.
1- 4 correct answers - 1 point
5-7 correct answers - 2 points
8-10 correct answers - 3 points
3) The captains receive cards with the task. It is necessary to arrange the coefficients in the reaction equations.
IV . ISLAND ZHZL
Reports of students "Biography Pages" (Democritus, Lomonosov, Lavoisier, Mendeleev)
Report - 2 points
V . ARCHIPELAGO LABORATORY
Island Safe. ( Physical education minute )
Let's repeat the basic rules of behavior in the laboratory when performing experiments.
Correct statement - students nod their heads, incorrect - turn their heads from side to side, doubt - shrug their shoulders.
It is necessary to work in the laboratory in a special coat.
Substances must be taken in small quantities.
Substances can be tasted.
Any work will be done with the permission of the teacher or laboratory assistant.
You can confuse bottles and lids.
Extinguish the burner flame with a special cap.
Excess reagents can be poured back into the vial from which they were taken.
When working with caustic substances (acids and alkalis), it is necessary to be especially careful and careful.
Experimental Island.
At the beginning of our journey, each team received a task that must be completed, provided that the crew successfully passed all the previous stages of the journey.
Island Productive.
Having completed the practical task, the team draws up the result of their work on the board, compiling a comparative table “Physical and chemical phenomena”, explaining their observations and conclusions. (A radio operator works at the board). All students write the table in a notebook. (Interactive exercise Compiling a Comparison Table)
physical phenomena
chemical phenomena
Melting of paraffin (change of state of aggregation)
"Fizz" (gas release)
Evaporation of water (change in state of aggregation)
"Milk" (discoloration, sedimentation)
VI . ISLAND OF CHEMICALS
This is the end point of our voyage, where we will sum up our work. I ask the captains to calculate the amount of points and hand over the waybills.
At this time, students are invited to watch a video clip of the m / f "Imp No. 13"
Homework
Summarizing
Evaluation of student work for the lesson
Stages of the path
Members
crew
Customs
Island of chemical signs and formulas
Island of Change
ZhZL
Archipelago Laboratory
Captain
Boatswain
Pilot
radio operator
Sailor
Stages of the path
Members
crew
Customs
Island of chemical signs and formulas
Island of Change
ZhZL
Archipelago Laboratory
Mainland Chemicals (total points)
Captain
Boatswain
Pilot
radio operator
Sailor
Democritus (he was also called Democritus from Abder by his place of birth) - an ancient Greek philosopher, the first materialist, one of the first representatives of atomism. His achievements in this area are so great that for the entire era of modernity, any fundamentally new conclusions have been added to them in a very small amount.
From his biography, we know only fragmentary information. Democritus was born around 470 BC. e. His homeland was Thrace, a region of Eastern Greece, the seaside city of Abdera.
The legend says that Democritus was a student of some Chaldeans and magicians.
The baggage of knowledge and experience has increased significantly in the course of numerous trips and travels. It is known that he visited such countries as Persia, Egypt, Iran, India, Babylonia, Ethiopia, got acquainted with the culture and philosophical views of the peoples living there. For some time he lived in Athens, listened to the lectures of Socrates.
The main achievement of the philosophy of Democritus is considered to be his development of the doctrine of the "atom" - an indivisible particle of matter that does not collapse and does not arise. He described the world as a system of atoms in a void, proving not only the infinity of the number of atoms in the universe, but also the infinity of their forms. Atoms, according to this theory, move randomly in empty space (the Great Void, as Democritus said), collide and, due to the correspondence of shapes, sizes, positions and orders, either stick or fly apart. The resulting compounds hold together and thus produce complex bodies. Movement itself is a property naturally inherent in atoms. Bodies are combinations of atoms. The diversity of bodies is due both to the difference in the atoms that compose them, and to the difference in the order of assembly, just as different words are made up of the same letters.
Indeed, Democritus possessed such an encyclopedic, extensive and versatile knowledge that he deserves the title of the predecessor of the famous Aristotle. In his contemporary era, there were no sciences in which he would not be engaged: these are astronomy, ethics, mathematics, physics, medicine, technology, music theory, philology. Nevertheless, the emergence of such a universal philosophical doctrine as atomism is usually associated precisely with the theories of Democritus.
He died approximately in 380 BC. e.
Mikhail Vasilievich Lomonosov - the great Russian scientist-encyclopedist, naturalist and philologist, poet and artist, philosopher of natural sciences.
Mikhail Vasilievich Lomonosov was born in the village of Denisovka near the village of Kholmogory, Arkhangelsk province, in the family of a Pomor peasant. At the age of 19, he left home for Moscow, where, under a fictitious noble name, he entered the Slavic-Greek-Latin Academy. Among the best students, Lomonosov was sent to continue his education at the university at the St. Petersburg Academy of Sciences, and then abroad, where he improved in chemistry, physics, and metallurgy. At 34, he became one of the first Russian academicians. The range of his interests and research in natural science covered the most diverse areas of fundamental and applied sciences (physics, chemistry, geography, geology, metallurgy, astronomy). Lomonosov penetrated deeply into the materialistic essence of nature, promoted and developed its basic physical and philosophical principles: the law of conservation of matter and motion, the principles of knowability, the laws of nature.
The ability to analyze phenomena in their interconnection and the breadth of interests led him to a number of important conclusions and achievements. He showed particular interest in the creation of such instruments that would help sailors better navigate the stars and determine the time with the greatest accuracy.
M. V. Lomonosov claims that all substances consist ofmolecules which are "gatherings" . In his dissertation “Elements of Mathematical Chemistry” (1741; unfinished), the scientist gives the following definition: “Atom is a part of a body that does not consist of any other smaller and different bodies ... A molecule is a collection of atoms that forms one small mass.” Lomonosov's atoms and molecules are often also "physical insensitive particles", which emphasizes that these particles are sensually imperceptible. M. V. Lomonosov points to the difference between “homogeneous” molecules, that is, consisting of “the same number of the same elements connected in the same way”, and “heterogeneous” - consisting of different elements. Bodies consisting of homogeneous molecules are simple bodies.
In a letter to L. Euler, he formulates his "universal natural law" (July 5, 1748)... All the changes that occur in nature are such a state that how much of what is taken away from one body, so much will be added to another, so if where a few matter decreases, it will multiply in another place ... This universal natural law extends to the most rules of motion, for a body that moves another by its own power loses as much of them from itself as it communicates to another, which receives motion from it.
In 1774 publishes a paper describing similar experiments; later he formulated and published the law of conservation of matter - the results of the experiments of M. V. Lomonosov were not published, so they became known only after a hundred years.
Antoine Laurent Lavoisier - French chemist, one of the founders of modern chemistry. Born August 26, 1743 in Paris in the family of a lawyer.
In his research he constantly used mathematical methods. He found out the role of oxygen in the process of combustion, oxidation and respiration, thereby disproving the theory of phlogiston, discovered the law of conservation of mass of substances, introduced the concept of "chemical element" and "chemical compound", proved that respiration is similar to the combustion process and is a source of heat in the body. Lavoisier is considered one of the founders of thermochemistry.
At 29, Lavoisier was elected a full member of the Paris Academy of Sciences. Who knows what other discoveries this outstanding scientist would have made if he had not been killed along with the victims of revolutionary terror.
In the history of world science, the names of famous scientists are imprinted, whose discoveries contributed to the progress of our knowledge about nature, their use for the benefit of man. Among them, the name of D. I. Mendeleev occupies one of the first places.
Dmitri Ivanovich Mendeleev born January 27, 1834 in Tobolsk. He was the seventeenth child in the family. In the gymnasium, he studied mediocre at first. In high school I became interested in natural sciences, mathematics, history, geography, astronomy. Over time, the success of the young schoolboy grew, and in the certificate there were only two satisfactory grades. And in 1855, Mendeleev brilliantly graduated from the Main Pedagogical Institute in St. Petersburg with a gold medal.
While still a student in 1854, Dmitry Ivanovich conducts research and writes an article "On isomorphism", where he established the relationship between the crystal form and the chemical composition of compounds, as well as the dependence of the properties of elements on the magnitude of their atomic volumes.
In 1856 he defended his dissertation "On specific volumes" for a master's degree in chemistry and physics. At this time, he writes about the difference between substitution, combination and decomposition reactions.
Since 1880, he began to take an interest in art, especially Russian art, collects art collections, and in 1894 he was elected a full member of the Imperial Academy of Arts. As a hobby, Dmitry Ivanovich made suitcases and sewed clothes for himself. Mendeleev also participated in the design of the first Russian icebreaker "Ermak".
The discovery of the periodic law by D.I. Mendeleev marked the beginning of a new stage in the development of chemistry in general, played an important role in the creation of the theory of the structure of the atom. Mendeleev's ideas about solutions formed the core of modern theories of solutions.
The activity of D.I. Mendeleev, aimed at the development of industry and agriculture.
His work on the creation of smokeless powder, aero- and hydrodynamics, contributed to the development of the Arctic Ocean, the development of navigation, aeronautics, meteorology, and contributed to the scientific and technological progress of the country.
Mendeleev repeatedly traveled around the country in order to study the possibility of developing one or another of its regions, including Ukraine. The scientist visited Donbass and expressed the idea of underground fuel gasification.
INTRODUCTION
The theme "Initial Chemical Concepts" begins the course of chemistry in the eight-year secondary school. The significance of the topic is determined not only by the fact that when studying it, students will learn many chemical concepts, the law of conservation of mass of substances, the basic provisions of atomic and molecular theory, but also by the fact that it provides an opportunity for the development of students' logical thinking, educating their interest in the subject, dialectical materialistic worldview.
1. PRIMARY CHEMICAL CONCEPTS
The formation of initial concepts in the lessons on this topic is the first stage in the creation of a system of chemical knowledge among students, so many definitions will not yet be complete, will not contain all the features of the concepts being studied. Chemical phenomena must be considered from the point of view of atomic and molecular science. When studying this topic, the formation of students' skills to carry out interdisciplinary connections begins. The peculiarity of the methodology for implementing interdisciplinary connections is that students follow the teacher to a greater extent, reproduce his story containing facts, concepts known from other subjects, especially from physics courses of VI and early VII grades. The teacher himself shows the possibility and necessity of attracting knowledge, for example, information about the properties of specific substances (metals, non-metals, etc.). At the end of the first topic, students can independently draw on the theoretical knowledge gained in physics lessons.
In the process of assimilation of the initial chemical concepts, worldview knowledge (positions and ideas) should be formed on the basis of material accessible to students, mainly on the basis of interdisciplinary connections. It is known that many worldview ideas have already been incorporated into the minds of students in the study of biology, geography, and physics. Therefore, it is important to skillfully use and develop them.
An important role in solving the problem of forming a scientific worldview is played by the generalizations that the teacher makes. At the same time, it goes without saying that students are introduced to worldview knowledge at the level of the chemical form of the movement of matter. When explaining and generalizing, you can use some philosophical terms, such as essence, law, reason, opposite, etc. However, the teacher does not disclose these terms, but only explains them, based on everyday ideas and the knowledge that students have. When studying a topic, the worldview material should be mastered by students mainly at the level of reproduction, although it is also possible to apply this knowledge in similar situations.
The main objectives of studying the topic are as follows: to give an idea of substances, their composition, structure, and also to show the comprehensibility of the composition and structure, their connection with properties and applications; explain one of the reasons for the diversity of substances - the ability of atoms of different elements to combine with each other; reveal the essence of chemical transformations and their external manifestations, introduce the variety of chemical reactions and their first classification, emphasize the relationship of phenomena in nature (chemical - with each other; chemical - with physical and biological); explain to students the generalized chemical knowledge (at the atomic-molecular level) contained in the laws and theories of chemistry; show the significance of this knowledge for understanding the world of substances and human practice; to acquaint schoolchildren with some methods of chemistry (observation, chemical experiment), with the chemical language, methods of thinking (comparison, highlighting the essential, generalization, concretization) and ways of knowing.
The topic "Initial chemical concepts" is studied in 22 lessons: 1. The subject of chemistry. Substances and their properties.
- 2. Practical lesson 1. "Familiarization with the safety rules when working in the chemistry room and with laboratory equipment."
- 3. Practice, 1 (continued). "Familiarization with heating devices. The study of the structure of the flame.
- 4. Pure substances and mixtures.
- 5. Practical lesson 2. "Cleaning salt",
- 6. Physical and chemical phenomena. Signs and conditions of chemical reactions.
- 7. Atoms and molecules.
- 8. Simple and complex substances,
- 9. Chemical elements.
- 10. Signs of chemical elements.
- 11. Relative atomic mass.
- 12. The constancy of the composition of substances. Chemical formulas.
- 13. Relative molecular weight. Calculation of the mass fraction of an element in a "complex substance by a chemical formula.
- 14. Valence of atoms.
- 15. Drawing up formulas for valency.
- 16. Atomic-molecular theory in chemistry. 17. The law of conservation of mass of substances.
- 18. Chemical equations.
- 19. Types of chemical reactions. Reactions of decomposition and connection.
- 20. Substitution reaction. Exercises in writing and reading chemical equations.
- 21. Repetition and generalization of the topic "Initial chemical concepts".
- 22. Control work.
Before revealing the methodology for studying program issues, the chemical experiment of the first topic is briefly characterized from the point of view of the changes made to it. The number and content of laboratory experiments remained the same, with the exception of the fifth experiment, in which students are invited to additionally familiarize themselves with samples of minerals and rocks. The set of substances, items recommended for experiments may be different (at the discretion of the teacher). You can also change the technique of performing individual experiments, for example, to study physical phenomena, an experiment is proposed to heat a glass tube. Practice shows; that the heating of a glass tube on an alcohol burner takes a long time. In this case, a lot of fuel is expended. It is even more difficult to conduct an experiment if dry alcohol is used. In this regard, the experience of heating: a glass tube can be replaced by dissolving substances known to students in water (table salt, soda, sugar) and evaporating the resulting solution (a few drops).
Students can study chemical phenomena in various experiments: the effect of a solution of acetic acid (“vinegar”) on soda, the effect of a solution of hydrochloric acid on small pieces of marble (with chalk, as recommended in the textbook, the experiment is less clear), calcining a copper object, etc. Experience with annealing copper needs to be changed. Since the purpose of the experiment is to notice the formation of a new substance, it makes no sense to ignite the copper several times, as the textbook recommends, and each time scrape off the black plaque (this procedure is time consuming). Regarding other experiments used to prove chemical phenomena, attention should be paid to the need to use small amounts of reagents.
Compared with the previous program, not one, but three hours are allotted for practical classes in this topic. One hour is added to familiarize students with the technique of laboratory work, to study the structure of the flame and safety rules when working in the chemistry room. The second hour is allocated for the practical lesson "Cleaning contaminated table salt."
BASIC CONCEPTS AND LAWS OF CHEMISTRY
§one. The subject of chemistry. Substances and their properties
Chemistry is the science of substances and their transformations. It studies the composition and structure of substances, the dependence of their properties on the structure, the conditions and methods for the transformation of one substance into another.
Matter is what physical bodies are made of. Now more than 20 million substances are known. Each of them can be characterized by certain properties. Properties of substances are signs by which substances are similar or differ from each other.
The main physical properties of substances:
state of aggregation
solubility in water
color
smell
taste
density
boiling temperature
melting temperature
electrical conductivity
thermal conductivity
Chemistry has great practical applications. Many millennia ago, man used chemical phenomena in the smelting of metals from ores, obtaining alloys, melting glass, etc. Back in 1751, M.V. Lomonosov, in his famous “Sermon on the Benefits of Chemistry,” wrote: “Chemistry widely spreads its hands in human affairs. Wherever we look, wherever we look, the successes of its application turn before our eyes.” At present, the role of chemistry in the life of society is indisputable and immeasurable. Chemical knowledge has now reached such a level of development that, on its basis, man's ideas about the nature and mechanism of a number of important technological processes are radically changing. Chemistry helped to discover and use not only previously unknown properties of substances and materials, but also to create new substances and materials that do not exist in nature.
§2. Pure substances and mixtures
Pure substances are those that consist of a given type of it and contain others only in small (certain) quantities.
When the names nitrogen, oxygen, copper, water, sulfuric acid, methane, glucose and others are used in chemistry, it should be understood that pure substances are meant. If they say, for example, natural water, battery sulfuric
acid, industrial soda, natural gas, then we are talking about mixtures of substances ("heterogeneous" substances).
In industry, technology and everyday life, natural mixtures are often used, for example, air, granite, wood, milk, etc. Artificially obtained mixtures or materials are also widely used: glass, cement, metal alloys, plastics, synthetic fibers, rubber.
The concept of "pure" substance is conditional. There are no absolutely pure substances. The purity of substances is determined by the content of impurities in percent. Therefore, ultrapure substances are distinguished (containing impurities of 10-7% and below), chemically pure, technically pure substances. The following methods are used to purify substances:
upholding
filtration
magnet action
evaporation
distillation
chromatography
crystallization
§3. Atomic-molecular doctrine
The first one defined chemistry as a science by M.V. Lomonosov. He believed that chemistry should be based on accurate quantitative data - "on measure and weight." M.V. Lomonosov created the doctrine of the structure of matter, laid the foundation for the atomic and molecular theory. This doctrine is reduced to the following provisions, set forth in the work "Elements of Mathematical Chemistry"
1. Each substance consists of the smallest, further physically indivisible particles (M.V. Lomonosov called them corpuscles, later they were called molecules).
2. Molecules are in constant spontaneous motion.
3. Molecules consist of atoms (MV Lomonosov called them elements).
4. Atoms are characterized by a certain size and mass.
5. Molecules can be made up of the same or different
A molecule is the smallest particle of a substance that retains its composition and chemical properties.
Between the molecules of a substance there is a mutual attraction, which is different for different substances. Molecules of gaseous substances are attracted to each other very weakly, while between the molecules of liquid and solid substances, the forces of attraction are great. The molecules of any substance are in continuous
movement. This explains, for example, changes in the volume of substances when heated, as well as the phenomenon of diffusion.
§four. Atom. Chemical element
Atoms are the smallest, chemically indivisible particles that make up matter.
An atom is the smallest particle of an element that retains its chemical properties. Atoms differ in nuclear charges, mass and size.
In chemical reactions, atoms do not arise and do not disappear, but by rearranging during the reaction, they form molecules of new substances. Since the only characteristic of an atom that determines its belonging to one or another element is the nuclear charge, the element should be considered as a type of atoms that have the same nuclear charge.
The chemical properties of atoms of the same element are the same, such atoms can differ only in mass.
Varieties of atoms of the same element that have different masses are called isotopes.
There are more varieties of atoms than chemical elements.
Currently, 117 elements are known. In nature, they are not found in equal quantities. It is necessary to distinguish between the concepts of "chemical element" and "simple substance". Chemical element - general concept of atoms with the same chemical properties and nuclear charge. The physical properties characteristic of a simple substance cannot be attributed to a chemical element. A simple substance is a form of existence of an element in a free state. One and the same element can form several different simple substances.
§5. Chemical symbolism
Chemical symbols have been introduced to designate chemical elements. Each element has its own symbol. Symbols, as a rule, consist of the initial letters of the Latin names of the elements. For example, oxygen - Oxygenium - is denoted by the letter O, carbon - Carboneum - by the letter C, etc. If the initial letters of the Latin names of various elements are the same, then the second letter is added to the first letter. So, the initial letter of the Latin name for sodium (Natrium) and nickel (Niccolum) is the same, so their symbols are respectively Na and Ni. If by the symbol of a chemical element we mean its atom, then, using the symbols, one can compose, one can compose the chemical formulas of substances.
Chemical formula- this is a representation of the composition of a substance through chemical symbols.
For example, the formula H 3 PO 4 shows that the phosphoric acid molecule contains hydrogen, phosphorus and oxygen and that this molecule
contains 3 hydrogen atoms, 1 phosphorus atom and 4 oxygen atoms. The numbers at the bottom right after the symbol of the element indicate the number of atoms of this element in the molecule of the substance.
The chemical formula of a compound provides very important information, not only qualitative, but also quantitative. Yes, it shows:
c) the chemical formula makes it possible to make quantitative (stoichiometric) calculations. To do this, you need to know how it is customary in chemistry to express the masses of atoms and molecules.
§6. Simple and complex substances Allotropy
Molecules are formed from atoms. Depending on whether the molecule consists of atoms of the same element or of atoms of different elements, all substances are divided into simple and complex.
Simple substances are substances formed by atoms of one element. For example, simple substances can be composed of one (He , Ne , Kr , etc.),
two (O 2, N 2, Cl 2, H 2, etc.) and more atoms (S 8 ) of one element.
As already noted, the same element can form several simple substances. The ability of a chemical element to exist in the form of several simple substances is called allotropy. Simple substances formed by the same element are called allotropic modifications this element. These interactions of the same element can differ both in the number (O 2 and O 3 ) and in the arrangement (diamond, graphite) of the same atoms in the molecule. The phenomenon of allotropy is a clear confirmation of the dependence of the properties of substances on the spatial structure.
complex substances, or chemical compounds, are substances whose molecules consist of atoms of two or more elements.
For example: H 2 O, CO 2, CaCO 3 etc.
Atoms that have entered into a chemical combination with each other do not remain unchanged. They influence each other mutually. That is why the molecules of a complex substance have properties inherent only to them and cannot be considered as a simple sum of atoms.
In the molecules of complex substances, it is impossible to detect properties characteristic of the initial simple substances, since the molecules of complex substances consist of atoms of chemical elements:
2H 2 + O 2 \u003d 2H 2 O.
A molecule of a complex substance of water consists of atoms of chemical elements - hydrogen and oxygen, and not of substances - hydrogen and oxygen.
Elements do not appear or disappear in chemical reactions. Entering into a chemical interaction, the molecules of simple substances, simultaneously with crushing into individual atoms, lose their properties.
§7. Mole as a unit of quantity of a substance Molar mass
During the course of various chemical reactions, atoms and molecules of the initial substances enter into interaction, and in order for them to react completely, they must be taken in appropriate quantities. For example, for the complete combustion of a certain amount of coal in oxygen according to the reaction C + O 2 → CO 2
One molecule of oxygen is consumed per carbon atom. But it is practically impossible to count atoms and molecules, just as it is impossible to measure their number in atomic mass units. For these purposes, a special physical quantity is used in chemistry, which is called amount of substance.
The amount of a substance and mass are two different independent quantities that are the main ones in the International System of Units.
Amount of substance ν(nu) is a dimensional physical quantity determined by the number of structural particles contained in this substance (atoms, molecules, ions, etc.).
In SI, the unit of quantity of a substance is the mole.
A mole is equal to the amount of a substance that contains as many structural particles of a given substance as there are atoms in a quantity of carbon weighing 12 g.
From this it follows that 1 mole of any substance has such a mass in grams, which is equal to the mass of its structural particle in atomic mass units.
The mass of 1 mole of a substance in grams, or the ratio of the mass of a substance to its quantity, is called molar mass ( M ): M = m ν , where m is the mass
substances, g; ν is the amount of substance, mol. Therefore, the unit of molar mass is grams per mole (g/mol). Using this formula, it is easy to calculate the mass of a substance, knowing its quantity, and vice versa.
The volume of 1 mole of a substance, or the ratio of the volume of a substance to its quantity,
called molar volume ( V m ) : V m = V ν , where V is the volume of the substance, l; ν-
amount of substance, mol. So, the molar volume is expressed in liters per mole (l/mol).
For all gaseous substances taken under normal conditions (0 ° C, 760 mm Hg), the molar volume is the same and equal to 22.4 l / mol.
In the equations of chemical reactions, the coefficients indicate the ratio of the number of moles of reactants. If these substances are gaseous, then the coefficients also express the ratio of volumes. For example, from the reaction equation 2 H 2 + O 2 → 2 H 2 O, it follows that when water is formed, hydrogen and oxygen react in a 2:1 mole volume ratio. But this ratio will be preserved if the reaction equation is written as H 2 +0.5 O 2 → 2 H 2 O, i.e., the coefficients can be fractional.
AT 1 g contains 6.02 10 23 atomic mass units. This is
a consequence of the fact that, as established experimentally, 1 mole of any particles is equal to 6.02 1023 of these particles. This value is called constant Avogadro. Avogadro's number is colossal in magnitude. It is, for example, immeasurably greater than the number of hairs of all the inhabitants of the globe.
AT In conclusion, let's pay attention to the fact that in SI the basic unit of mass is not grams, but kilograms and volume is expressed not in liters, but in cubic meters. However, in practice, the use of grams and liters is allowed.
§eight. Phenomena physical and chemical
A substance is a type of matter that, under certain conditions, has constant physical and chemical properties.
However, as conditions change, the properties of matter change.
Any changes that occur with matter are called phenomena. Phenomena are physical and chemical.
Physical phenomena are called phenomena that lead to a change, for example, in the state of aggregation or the temperature of a substance. The chemical composition of substances does not change as a result of a physical phenomenon.
So, water can be turned into ice, into steam, but its chemical composition remains the same.
Chemical phenomena are those phenomena in which there is a change in the composition and properties of a substance. Chemical phenomena are otherwise called chemical reactions.
As a result of chemical reactions, some substances are transformed into others, i.e. molecules of new substances are formed. However, atoms in chemical reactions remain unchanged. An example is the decomposition of limestone
CaCO3 → CaO + CO2
or formation of copper(II) oxide
2Cu + O 2 → 2CuO .
§9. Basic laws of chemistry
LAW OF CONSERVATION OF MASS OF SUBSTANCE
It was first expressed by M.V. Lomonosov in a letter to Euler dated June 5, 1748, published in Russian in 1760: “All changes that occur in nature are of such a state that how much is taken from one body, so much is added to another ...” This is a definition, with the exception of the archaic language, is not obsolete.
The law is currently worded as follows:
the mass of the substances that entered into the reaction is equal to the mass of the substances resulting from the reaction.
It follows from the law of conservation of mass that the atoms of elements are preserved during chemical reactions, do not arise from nothing, just as they do not disappear without a trace, for example:
2Hg + O2 → 2HgO.
How many hydrogen atoms entered into the reaction, so many of them remain after the reaction, i.e. the number of element atoms in the starting substances is equal to their number in the reaction products.
THE LAW OF CONSTANT COMPOSITION
It was discovered by the French chemist J. Proust after a thorough analysis of numerous chemical compounds.
The law can be formulated as follows:
any pure substance (chemical compound), no matter how it is obtained, has a strictly defined and constant composition (qualitative and quantitative).
For example, water can be obtained as a result of the following chemical reactions:
2H 2 + O 2 → 2H 2 O;
Ca(OH)2 + H2SO4 → CaSO4 + 2H2O;
Cu(OH)2 → H2O + CuO.
It can be seen from these equations that a molecule of water obtained by various methods always consists of two hydrogen atoms and one oxygen atom. This law is strictly observed only for substances whose structural particles are molecules.
LAW OF MULTIPLE RATIO
There are cases when two elements, combining with each other in different mass ratios, form several different chemical compounds. So, carbon and oxygen form two compounds of the following composition: carbon monoxide (II) (carbon monoxide) CO - 3 mass parts of carbon and 4 mass parts of oxygen; carbon monoxide (IV) CO 2 - 3 mass parts of carbon and 8 mass parts of oxygen. The mass parts of oxygen in these
compounds for the same mass amount of carbon (3 mass parts) are treated as 4:8 or 1:2.
Taking into account the data on the quantitative composition of various compounds formed by two elements, and based on their atomistic ideas, the English chemist Dalton in 1803 formulated law of multiple ratios.
If two elements form several compounds with each other, then for the same weight amount of one element there are such weight amounts of the other element that are related to each other as small integers.
The fact that the elements enter into compounds in certain portions was another confirmation of the fruitfulness of the application of the atomistic doctrine to explain the nature of chemical processes.
LAW OF VOLUME RELATIONS
Atomistic concepts alone could not explain certain factors, such as the quantitative relationships that are observed during chemical reactions between gases.
The French scientist J. Gay-Lussac, studying chemical reactions between gaseous substances, drew attention to the ratio of the volumes of reacting gases and gaseous reaction products. He found that 1 liter of chlorine completely reacts with 1 liter of hydrogen to form 2 liters of hydrogen chloride; or 1 liter of oxygen interacts with 2 liters of hydrogen and this produces 2 liters of water vapor. Gay-Lussac generalized these experimental data in the law of volumetric ratios.
The volumes of reacting gaseous substances are related to each other and to the volumes of gaseous products formed as small integers.
To explain this law, it was assumed that equal volumes of simple gases, such as oxygen, hydrogen, chlorine, under the same conditions, contain the same number of atoms. However, many experimental data contradicted this assumption. It became clear that Gay-Lussac's law of volumetric ratios could not be explained solely on the basis of these mystical ideas.
LAW OF AVOGADRO
This law was put forward as a hypothesis by the Italian scientist Avogadro
in 1841:
in equal volumes of different gases under the same conditions contain the same number of molecules.
Avogadro's law applies only to gaseous substances. This is explained by the fact that in a substance in a gaseous state, the distances between molecules are incommensurably greater than their sizes. Therefore, own volume
molecules is very small compared to the volume occupied by the gaseous substance. The total volume of a gas is determined mainly by the distances between molecules, which are approximately the same for all gases (under the same conditions).
In solid and liquid states, the volume of the same number of molecules of a substance will depend on the size of the molecules themselves.
§ten. The original concept of valence
Considering the formulas of various compounds, it is easy to see that the number of atoms of the same element in the molecules of different substances is not the same. For example, HCl, H 2 O, NH 3, CH 4, CaO, Al 2 O 3, CO 2, etc. The number of hydrogen and oxygen atoms per atom of various elements is different.
How is the chemical formula of a substance formed? This question can be answered by knowing the valency of the elements that make up the molecule of a given substance.
Valency is the property of an atom of one element to attach, hold or replace a certain number of atoms of another element in chemical reactions.
The unit of valency is the valency of the hydrogen atom. Therefore, the above definition is sometimes formulated as follows: valence is the property of an atom of a given element to attach or replace a certain number of hydrogen atoms.
If one hydrogen atom (HCl) is attached to the atom of one or the element, then the element is monovalent, if two are divalent, etc.
But what happens when it does not combine with hydrogen? Then the valency of the desired element is determined by the element whose valency is known. Most often, it is found by oxygen, since the valence of oxygen in compounds is always equal to two. For example, it is not difficult to find the valence of elements in the compounds Na 2 O, MgO, CO, Al 2 O 3, P 2 O 5, Cl 2 O 7, etc.
Only knowing the valency of the elements, it is possible to compose the chemical formula of a given substance. In examples like CaO , BaO , CO , this is easy. Here the number of atoms in the molecules is the same, since the valencies of the elements are equal.
And if the valencies are not the same? How then to write a chemical formula? In such cases, one must always remember that in the formula of any chemical compound, the product of the valence of one element by the number of its atoms in the molecule is equal to the product of the valence by the number of atoms of another element. For example, if the valence of Mn in a compound is VII, and the valency of oxygen is II, the formula of the compound will be:
Mn 2 O 7 (VII 2 → II 7).
Valency is indicated by Roman numerals above the chemical sign
write in brackets a number indicating the valence of a given element in this compound. For example, SnO 2 is tin (IV) oxide, CuCl 2 is copper (II) chloride. And in the names of substances formed by elements with constant valency, valence is not indicated. For example, Na 2 O is sodium oxide, AlCl 3 is aluminum chloride.
§eleven. Compilation of chemical equations
Any chemical reaction can be represented as a chemical equation, which consists of two parts connected by an arrow. On the left side of the equation, the formulas of the substances entering into the reaction are written, and on the right - the substances obtained in the reaction.
chemical reaction equation called the conditional record of a chemical reaction using chemical formulas and coefficients.
The chemical equation expresses both the qualitative and quantitative side of the reaction t is compiled on the basis of the law of conservation of mass and matter.
To write a chemical equation Initially, the formulas of the substances that have entered into the reaction and those resulting from the reaction are written down, and then the coefficients for the formulas of those and other substances are found. After placing the coefficients, the number of atoms in the substances that have entered into the reaction must be equal to that in the substances obtained after the reaction. For example, in the final form, the reaction equation for the interaction of metallic zinc with hydrochloric acid can be written:
Zn + 2HCl → ZnCl2 + H2 .
It is obtained in the following way. When zinc reacts with hydrochloric acid, zinc chloride (ZnCl 2 ) is formed and free hydrogen is released. But since the hydrochloric acid molecule contains only one hydrogen atom and one chlorine atom on the left side of the equation, then, according to the law of conservation of mass of a substance, two molecules of hydrochloric acid must enter into the reaction. From the original entry
Zn + HCl → ZnCl2 + H2
by the above method, we obtain the final
Zn + 2HCl → ZnCl2 + H2 .
§12. Main types of chemical reactions
There are several types of classification of chemical reactions.
I. Classification according to the number of substances involved in the reaction
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Presentation - Initial chemical concepts
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Prepared by the teacher of chemistry Alimova E.N. MOU "Volnovskaya school" Republic of Crimea, P.Volnoe
2015
Extracurricular event on the topic "Initial chemical concepts"
generalize the initial chemical concepts; be able to draw up chemical formulas, carry out calculations according to the formulas of substances, conduct experiments on the separation of mixtures, the ability to use chemical glassware and equipment. To be able to work in a team and independently, highlight the main thing, compare, draw conclusions.
Goals:
Competition No. 1 "Warm-up"
What does the science of chemistry study? What is a substance? What is an atom? What is a molecule? What substances are called complex? What is a formula? What does the index and coefficient mean? How is relative molecular weight calculated? How to calculate the mass fraction of an element in a compound? State the law of conservation of mass of matter.
Competition No. 2 "Guess the rebus"
Team #1. Mg B Fe K C Pt (molecule) 1 2 3.4 1 1 2.3 Li S H Hg Ca Fe Cu (Lavoisier) 1 4 1 3 2 5 4, 2 Team #2 As V C Na He (phenomenon) 5 1 3, 4 1, 5 2 Li Sn Cu Os Na Sn S Os W) by first letters.
Competition No. 3 "Define the phenomenon" Determine the type of phenomenon, write out the letter corresponding to the correct answer. Team 1
No. Phenomena Physical. Chemical
No. Phenomena Physical. Chemical
1 Burning candle n o
2 Drying laundry b and
3 Rusting of iron
4 Evaporation of water a l
5 Rotten eggs t h
6 Melting ice o d
7 Melting the candle in and
8 Wood rot for a
9 Frosting nu
10 Burning wood in and
11 Metal forging e k
12 Fog formation
13 Blackening of a silver spoon a c
14 The effect of vinegar on soda
15 Formation of snowflakes
16 Souring milk
17 Sauerkraut ma
I team
No. Phenomena Physical. Chemical
No. Phenomena Physical. Chemical
1 Burning candle to and
2 Drying laundry
3 Rusting of iron at m
4 Evaporation of water
5 Rancid eggs
6 Melting ice e f
7 Melting the candle
8 Wood decay b and
9 Frost formation
10 Burning wood
11 Metal forging a b
12 Fog formation
13 Blackening of a silver spoon with a
14 Formation of snowflakes x and
15 Bending the glass tube a t
16 The effect of vinegar on soda? .
Team 2
Physical education minute
H2O
NO2
CuO
CaSO4
H2CO3
H3PO4
H2SO4
Mn(OH)2
HNO3
HNO2
NaCl
HCl
HBr
KNO3
Fe2O3
H2SiO3
Ca3(PO4)2
Competition No. 4 "Signs of chemical phenomena"
Read an excerpt from a book. Emphasize the mention of a chemical reaction. Write down the sign of this reaction. “- I will pierce you with a sword, like a ram! shouted the merchant, and grabbed his sword. But the sword became so damp in the sea air that it became covered with rust and would not come out of its scabbard for anything. F. Rabelais "Gargantua and Pantagruel". “Dr. Ox… simply decomposed slightly acidified water with the help of a battery he invented… Electric current was passed through large vats filled with water, which decomposed into hydrogen and oxygen.” J. Verne. "The Experience of Dr. Oks".
Competition No. 5 "Chemist-erudite"
1st team, "Do you know valency?" Task number 1 a) Make formulas for complex substances formed by the element oxygen and the following elements: Mn(VII); Cr(VI); Si(IV); P(V); Al(III); Mg; Hg(I). b) Designate in Roman numerals the valency of elements in compounds with chlorine, knowing that in these compounds it is monovalent: KCl; CaCl2; FeCl3; PCl5; ZnCl2; CrCl3; SiCl4. 2nd team, "Do you know the valence?". Task No. 1 a) Make formulas for complex substances formed by the element oxygen and the following elements: Cl (VII); S(VI); As(V); Pb(IV); B(III); Zn; Cu(I). b) Designate in Roman numerals the valency of the elements in compounds with sulfur, knowing that in these compounds it is divalent: Al2S3; Na2S; MgS; CS2; Ag2S; ZnS; H2S.
Competition No. 5 "Chemist-erudite"
Team 1 Task #2 “Learn to equalize.” Arrange the coefficients in the equations of chemical reactions, indicate the types of chemical reactions. a) P+O2P2O5; b) NaNO3 → NaNO2 + O2 c) Al+CuCl2AlCl3+Cu. d) H2SO4 + KOH = K2SO4 + H2O Team 2 a) Fe+Cl2FeCl3; b) Zn+HCl→ZnCl2+H2 c) CH4C+H2. d) CuSO4+NaOH→NaSO4+Cu(OH)2
Physical education minute
There are a lot of safety rules, there are friends. We will tell you the main ones - After all, you can’t do without them! The experiment can be carried out only with permission, since they may not forgive your sins. (Tilts your head back and forth) To the nose, make with your hand Light movements That's when the sniffer is such Just a feast for the eyes! (Movement of the hands alternately to the nose) To dilute the acid Did you pour water into it? Badly! It can be seen from a mile away - It's not good! (Circular movements of the arms in the elbow joint)
The chemist, on the contrary, Here's how he does it. Acids will pour a little into the water and interfere. (Squeezing and unclenching the hands into a fist) You can't bend down to the flame in any way, Only, let's say, an eccentric Will start to burn. (Torso tilts forward) Drinking water from the tap - Everything is the same as Vanish. Thirst can be quenched, But you will become a kid! (Raising and lowering on tiptoe). Always remember: The rules are important, Knowing them, you will be friends with chemistry! (Turns of the body to the left, to the right, hands on the belt).
Competition No. 6 "Practical"
To prevent Cinderella from going to the ball, her stepmother came up with a job for her: she mixed wood shavings with small iron nails, sugar and river sand and told Cinderella to clean the sugar and put the nails in a separate box. Cinderella quickly completed the task and managed to go to the ball. Explain how you can quickly complete the stepmother's task.
Competition No. 7 "Problem Solving"
1) Calculate the mass fractions of the elements H3PO4, H2CO3 2) Determine the simplest formula of the compound containing, according to the analysis, 40% copper, 20% sulfur and 40% oxygen. Determine the simplest formula of the compound containing, according to the analysis, 24.7% potassium, 35% manganese, 41% oxygen.
Competition No. 8 "Who is he?"
Task: according to the description of the most important events in the life and work of the scientist, name his name. For the correct answer after the first clue - 15 points, after the second - 10 points, after the third - 5 points.
He - the pride of Russian science - embodied the national genius, the breadth and strength of the Russian character. For all ages, he left his Motherland an example of how science can and should serve the people. Tip 1. His research is known in the field of chemistry, physics, mathematics, astronomy, he was a scientist - an encyclopedist. Hint 2. He was the first physical chemist, created the first chemical laboratory and the first university. “He, better to say, he himself was our first university” (A.S. Pushkin) Hint 3. This scientist formulated in his writings the main provisions of the atomic and molecular theory
Competition "Who is he?"
He was a brilliant scientist, theory and practice have always been inextricably combined in his work. He was a passionate patriot and a bold defender of progressive ideas. Hint 1. This scientist was elected an honorary member of various Russian educational institutions and scientific societies, many foreign academies of sciences. Hint 2. His works on physics, mineralogy, meteorology, economics are known. Studies of the properties of solutions led the scientist to the conclusion about the chemical nature of the processes of dissolution. Tip 3. This scientist was able to combine disparate chemical knowledge into a certain system and was able to find a property that unites all chemical elements.
Reflection
Suitcase, grinder, basket
Suitcase - everything you need in the future
Meat grinder - I will process the information
Basket - I'll throw everything away
Thank you for the lesson!
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