Today we will conduct a lesson not only in modeling, but also in chemistry, and we will make models of molecules from plasticine. Plasticine balls can be represented as atoms, and ordinary matches or toothpicks will help to show structural connections. This method can be used by teachers when explaining new material in chemistry, by parents when checking and studying homework, and by children themselves who are interested in the subject. There is probably no easier and more accessible way to create visual material for mental visualization of micro-objects.

Here are representatives from the world of organic and inorganic chemistry as examples. By analogy with them, other structures can be made, the main thing is to understand all this diversity.

Materials for work:

• plasticine of two or more colors;
• structural formulas of molecules from the textbook (if necessary);
• matches or toothpicks.

1. Prepare plasticine for modeling spherical atoms from which molecules will be formed, as well as matches to represent the bonds between them. Naturally, it is better to show atoms of different types in a different color, so that it is clearer to imagine a specific object of the microworld.

2. To make balls, pinch off the required number of portions of plasticine, knead in your hands and roll into shapes in your palms. To sculpt organic hydrocarbon molecules, you can use larger red balls - this will be carbon, and smaller blue balls - hydrogen.

3. To form a methane molecule, insert four matches into the red ball so that they point towards the vertices of the tetrahedron.

4. Place blue balls on the free ends of the matches. The natural gas molecule is ready.

5. Prepare two identical molecules to explain to your child how the molecule of the next hydrocarbon, ethane, can be obtained.

6. Connect the two models by removing one match and two blue balls. Ethan is ready.

7. Next, continue the exciting activity and explain how a multiple bond is formed. Remove the two blue balls and make the bond between the carbons double. In a similar way, you can mold all the hydrocarbon molecules necessary for the lesson.

8. The same method is suitable for sculpting molecules of the inorganic world. The same plasticine balls will help you realize your plans.

9. Take the central carbon atom - the red ball. Insert two matches into it, defining the linear shape of the molecule; attach two blue balls, which in this case represent oxygen atoms, to the free ends of the matches. Thus, we have a carbon dioxide molecule of linear structure.

10. Water is a polar liquid, and its molecules are angular formations. They consist of one oxygen atom and two hydrogen atoms. The angular structure is determined by the lone pair of electrons on the central atom. It can also be depicted as two green dots.

These are the kind of exciting creative lessons you should definitely practice with your children. Students of any age will become interested in chemistry and will understand the subject better if, during the learning process, they are provided with a visual aid made by themselves.

Many schoolchildren do not like chemistry and consider it a boring subject. Many people find this subject difficult. But studying it can be interesting and educational if you approach the process creatively and show everything clearly.

We offer you a detailed guide to sculpting molecules from plasticine.

Before making molecules, we need to decide in advance what chemical formulas we will use. In our case, these are ethane, ethylene, methylene. We will need: plasticine in contrasting colors (in our case, red and blue) and some green plasticine, matches (toothpicks).

1. Roll 4 balls with a diameter of about 2 cm (carbon atoms) from red plasticine. Then roll 8 smaller balls from blue plasticine, about a centimeter in diameter (hydrogen atoms).

2. Take 1 red ball and insert 4 matches (or toothpicks) into it as shown in the picture.

3. Take 4 blue balls and put them on the free ends of the matches inserted into the red ball. The result is a molecule of natural gas.

4. Repeat step No. 3 and get two molecules for the next chemical substance.

5. The molecules made must be connected to each other with a match in order to form an ethane molecule.

6. You can also create a molecule with a double bond - ethylene. To do this, from each molecule obtained in step No. 3, take out 1 match with a blue ball on it and connect the parts together with two matches.

7. Take a red ball and 2 blue ones and connect them together with two matches so that you get a chain: blue – 2 matches – red – 2 matches – blue. We have another molecule with a double bond - methylene.

8. Take the remaining balls: red and 2 blue and connect them with matches as shown in the figure. Then we roll 2 small balls from green plasticine and attach them to our molecule. We have a molecule with two negatively charged electrons.

Studying chemistry will become more interesting, and your child will develop an interest in the subject.

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Choose a type of candy. To make side strands of sugar and phosphate groups, use hollow strips of black and red licorice. For nitrogenous bases, use gummy bears in four different colors.

• Whatever candy you use, it should be soft enough to be pierced with a toothpick.
• If you have colored marshmallows on hand, they are a great alternative to gummy bears.

Prepare the remaining materials. Take the string and toothpicks that you use to create the model. The rope will need to be cut into pieces about 30 centimeters long, but you can make them longer or shorter - depending on the length of the DNA model you choose.

• To create a double helix, use two pieces of string that are the same length.
• Make sure you have at least 10-12 toothpicks, although you may need a little more or less - again depending on the size of your model.

In addition to observation and experiment, modeling plays an important role in understanding the natural world and chemistry.

We have already said that one of the main goals of observation is to search for patterns in the results of experiments.

However, some observations are inconvenient or impossible to carry out directly in nature. The natural environment is recreated in laboratory conditions with the help of special devices, installations, objects, i.e. models (from the Latin modulus - measure, sample). Models copy only the most important features and properties of an object.

For example, in order to study the natural phenomenon of lightning, scientists did not have to wait for a thunderstorm. Lightning can be simulated in physics class and in the school laboratory. Two metal balls need to be given opposite electrical charges: positive and negative. When the balls approach a certain distance, a spark jumps between them - this is lightning in miniature. The greater the charge on the balls, the earlier the spark jumps when approaching, the longer the artificial lightning. Such lightning is produced using a special device called an electrophore machine (Fig. 33).

Rice. 33.
Electrophore machine

Studying the model allowed scientists to determine that natural lightning is a giant electrical discharge between two thunderclouds or between clouds and the ground. However, a real scientist strives to find practical application for each phenomenon studied. The more powerful the electric lightning, the higher its temperature. But the conversion of electrical energy into heat can be used, for example, for welding and cutting metals. This is how the electric welding process, familiar to every student today, appeared (Fig. 34).

Rice. 34.
The natural phenomenon of lightning can be simulated in the laboratory

Modeling in physics is used especially widely. In lessons on this subject, you will become familiar with a variety of models that will help you study electrical and magnetic phenomena, patterns of movement of bodies, and optical phenomena.

Each natural science uses its own models that help to visually imagine a real natural phenomenon or object.

The most famous geographical model is the globe (Fig. 35, a) - a miniature three-dimensional image of our planet, with which you can study the location of continents and oceans, countries and continents, mountains and seas. If an image of the earth's surface is applied to a flat sheet of paper, then such a model is called a geographic map (Fig. 35, b).

Rice. 35.
The most famous geographical models: a - globe; b - map

Models are widely used in the study of biology. It is enough to mention, for example, models - dummies of human organs, etc. (Fig. 36).

Rice. 36.
Biological models: a - eye; b - brain

Modeling is no less important in chemistry. Conventionally, chemical models can be divided into two groups: objective and symbolic, or symbolic (Scheme 1).

Subject models of atoms, molecules, crystals, chemical industrial plants are used for greater clarity.

You've probably seen a picture of a model of an atom that resembles the structure of the solar system (Fig. 37).

Rice. 37.
Atomic structure model

Ball-and-stick or three-dimensional models are used to model chemical molecules. They are assembled from balls symbolizing individual atoms. The difference is that in ball-and-stick models the ball atoms are located at a certain distance from each other and are fastened to each other by rods. For example, ball-and-stick and three-dimensional models of water molecules are shown in Figure 38.

Rice. 38.
Models of a water molecule: a - ball-and-rod; b - volumetric

Models of crystals resemble ball-and-stick models of molecules, however, they do not depict individual molecules of a substance, but show the relative arrangement of particles of a substance in a crystalline state (Fig. 39).

Rice. 39.
Copper crystal model

However, most often chemists use iconic, or symbolic, models rather than subject ones. These are chemical symbols, chemical formulas, equations of chemical reactions.

You will begin learning the chemical language of signs and formulas in the next lesson.

Questions and tasks

1. What is a model? modeling?
2. Give examples of: a) geographical models; b) physical models; c) biological models.
3. What models are used in chemistry?
4. Make ball-and-stick and three-dimensional models of water molecules from plasticine. What shape do these molecules have?
5. Write down the formula for the cruciferous flower if you studied this plant family in biology class. Can this formula be called a model?
6. Write down an equation to calculate the speed of a body if the path and time it takes the body to travel are known. Can this equation be called a model?

People have guessed for a very long time that substances consist of individual tiny particles; this was stated about 2500 years ago by the Greek scientist Democritus.

But if in ancient times scientists only assumed that substances consisted of individual particles, then at the beginning of the 20th century the existence of such particles was proven by science. The particles that make up many substances are called molecules 1.

A molecule of a substance is the smallest particle of that substance. The smallest particle of water is a water molecule, the smallest particle of sugar is a sugar molecule, etc.

What are the sizes of molecules?

It is known that a piece of sugar can be crushed into very small grains, and a grain of wheat can be ground into flour. The oil, spreading over the water, forms a film whose thickness is 40,000 times less than the thickness of a human hair. But both a grain of flour and the thickness of an oil film contain not one, but many molecules. This means that the size of the molecules of these substances is even smaller than the size of a grain of flour and the thickness of the film. The following comparison can be made: a molecule is the same number of times smaller than an average-sized apple as the apple is smaller than the globe.

Molecules of different substances differ in size, but they are all very small. Modern instruments - electron microscopes - have made it possible to see and photograph the largest of the molecules (see color plate II). These photographs are further confirmation of the existence of molecules.

Since molecules are very small, each body contains a great number of them. 1 cm 3 of air contains such a number of molecules that if you add up the same number of grains of sand, you will get a mountain that will cover a large factory.

In nature, all bodies differ from each other in at least some way. No two people have the same faces. Among the leaves growing on the same tree, no two are exactly alike. Even in a whole heap of sand we will not find identical grains of sand. Millions of balls for bearings are made at the factory according to one sample, the same size. But if you measure the balls more accurately than was done during processing, you can be sure that there are not two identical ones among them.

Do molecules of the same substance differ from each other?

1. Molecule is a Latin word meaning “small mass.”

Numerous and complex experiments have shown that the molecules of the same substance are identical. Each pure substance consists of identical molecules unique to it. This is an amazing fact. It is impossible, for example, to distinguish water obtained from juice or milk from water obtained by distilling sea water, since the molecules of water are the same and no other substance consists of the same molecules.

Although molecules are very small particles of matter, they are also divisible. The particles that make up molecules are called atoms.

For example, an oxygen molecule consists of two identical atoms. A water molecule consists of three atoms - one oxygen atom and two hydrogen atoms. Figure 14 shows two water molecules. This schematic representation of molecules is accepted in science; it corresponds to the properties of molecules studied in physical experiments and is called a molecule model.

The fission of two water molecules produces four hydrogen atoms and two oxygen atoms. Every two hydrogen atoms combine to form a hydrogen molecule, and every oxygen atom into an oxygen molecule, as shown schematically in Figure 15.

Atoms are also not indivisible particles; they are made up of smaller particles called elementary particles.

Questions. 1. What are the particles that make up substances called? 2. From what observations does it follow that the sizes of molecules are small? 3. What do you know about the sizes of molecules? 4. What do you know about the composition of the water molecule? 5. What experiments and reasoning show that all water molecules are the same?

Exercise. As you know, drops of an oily liquid spread over the surface of water, forming a thin film. Why does the oil stop spreading at a certain film thickness?

Exercise. Make models of two water molecules from colored plasticine. Then use these molecules to make models of oxygen and hydrogen molecules.