Teaching plan design of hot spot sports of physics molecules in senior one.
Thermal motion of molecules
Theme 7.2 Thermal Movement of Molecules The third class is planned to be held on the date:
Teaching goal (1) Know and remember what Brownian motion is, know the factors that affect the intensity of Brownian motion, and know the causes of Brownian motion;
(2) Know that Brownian motion is a reflection of irregular molecular motion;
(3) Know what molecular thermal motion is and the relationship between the intensity of molecular thermal motion and temperature. Brownian motion observed by students is not molecular motion, but indirectly reflects the characteristics of irregular motion of liquid molecules. This is a difficult point in class. This difficulty starts with the problem that molecular motion can't be seen under the analytical microscope, and gradually disperses to solve the problem. Teaching process content blackboard writing key guidance
Machining and polishing 1. In the following cases, molecules continue to do random motion ().
A. Autumn wind blows and leaves fall in succession.
B put some mothballs in the box, and you can smell camphor when you open the box in a few days.
C. the black smoke from the chimney floated in the air.
D. When sweeping the floor indoors, I saw dust flying under the sunlight.
Leaves, dust and black smoke (particles) are solid particles composed of several molecules, and their motion is not molecular motion. A, C and D are wrong and B is right. Answer B.
2. Among the four phenomena given below, () belongs to the diffusion phenomenon.
A. There are many small water droplets suspended in the sky after the rain.
B. Sponge absorbs water
C make the contact surface between a piece of lead and a piece of gold smooth. After polishing, press them tightly together. In a few years, gold will be found in lead.
D. mix rice and corn. Rice and corn are "you have me, I have you".
Analytical diffusion refers to the phenomenon that molecules of different substances enter each other. Obviously, A, B and D are not molecules that enter each other, and C belongs to diffusion. Answer C.
Open a bottle of perfume at one end of the room. If there is no air convection, people at the other end of the room can't smell the fragrance immediately, which is caused by the slow movement of molecules. Is this correct? Why?
The speed of analyzing the movement of gas molecules is actually very high. At room temperature, it is about105 m/s. The reason why we can't smell the fragrance immediately is that the molecular movement is irregular, constantly colliding with air molecules, and the direction of movement is constantly changing, so we can't always move in one direction. It takes a certain time for a large number of molecules to diffuse to another location, and people must reach a certain concentration to smell the fragrance.
Knowledge point 2 Brownian motion and molecular thermal motion
In a dark room, the movement of particles suspended in the air can be seen directly from the incident beam with the eyes.
( ).
A. Brownian motion
B. thermal motion of molecules
C. Free falling body motion
D. motion caused by the interaction of airflow and gravity
The essence of Brownian motion is the continuous impact of liquid or gas molecules on suspended particles, which move irregularly because of unbalanced force. Brownian motion can only be seen under a microscope. In this problem, the dust particles suspended in the air are too large to be directly seen by the naked eye, and the average impact effect of air molecules in all directions is balanced. In fact, the motion of these particles is a complex motion under the combined action of airflow and gravity. Therefore, item D is correct. Answer D.
5. Regarding the thermal motion of molecules, the following statement is true ().
A. Brownian motion is the thermal motion of molecules.
B Brownian motion is the random motion of molecules, and the molecular thermal motion intensity of the same substance is the same.
The thermal motion of gas molecules is not necessarily stronger than that of liquid molecules.
D the faster an object moves, the more intense the molecular thermal motion inside it.
Analytic Brownian motion refers to the motion of small solid particles, and A is wrong. The higher the temperature, the more violent the irregular movement of molecules. Regardless of the type of object, B is wrong and C is right. The thermal motion of small molecules of an object has nothing to do with the macroscopic motion speed, so C is chosen.
Answer c
6. There are particles doing Brownian motion in both glasses of water A and B. After observation with a microscope, it is found that the Brownian motion of particles in glass A is more intense than that in glass B. Among the following judgments, the correct one is ().
The water temperature in cup A is higher than that in cup B.
The water temperature in B.A cup is equal to that in B cup.
The water temperature in C.a cup is lower than that in B cup.
D. the conditions are not enough to judge the water temperature of two cups.
The intensity of Brownian motion is related to both the temperature of the liquid and the size of the particles, so it is impossible to judge which glass of water has a higher temperature according to the intensity of Brownian motion, so D is right. Answer D.
Three-molecule thermal movement of knowledge points
7. In the following phenomena, it can be explained that the molecule is constantly moving ().
A. You can smell the perfume by opening the bottle cap.
B. After the car left, dust was flying on the road.
C. the water spilled on the ground will dry up after a period of time.
D. Pollen suspended in water moves irregularly.
Analytical diffusion and Brownian motion can explain the continuous irregular motion of molecules. The diffusion of perfume, the diffusion of water molecules in the air and the movement of pollen suspended in water all indicate that molecules are constantly moving, so A, C and D are all correct, while dust is not a single molecule, but a particle, and flying dust is not a molecular movement, so B is wrong.
Answer ACD
Teaching plan design of hot sports of physics molecules in senior high school II
One teaching content: molecular heat exercises, lesson 1, lecture 2: objective knowledge and skills 1. Know that matter is made up of molecules, and all molecules of matter are constantly moving irregularly.
2. Diffusion can be understood and explained from the viewpoint of molecular thermal motion.
3. Know the relationship between molecular thermal motion and temperature.
4. Know that there are interactions between molecules.
Process and method 1. The demonstration experiment shows that the molecules of all substances are constantly moving irregularly.
2. Through the demonstration experiment, students can infer that the higher the temperature of the object, the more intense the thermal motion.
3. Through demonstration experiments, students can understand the repulsion and attraction between molecules by analogy with the elasticity of springs.
Emotional attitude values 1. Pay attention to the hot phenomena in life, and be willing to use the basic knowledge of molecular dynamics theory to explain the phenomena in life.
2. Interested in exploring the micro-mechanism of macro-phenomena. Third, the teaching focus
Key points of teaching difficulties: thermal movement of molecules.
Difficulty: Inferring the fact that can't be directly perceived through the phenomenon of direct perception.
Four teaching methods: inquiry teaching method and heuristic teaching method; Five teaching preparation.
The main contents of the teaching process are soap, nitrogen dioxide gas tank, empty bottle and lead cylinder. Problem introduction
If you break a glass, the fragments are still glass. After many times of division, the particles become smaller and smaller. Is there a limit if it is divided continuously?
Second, implement the new curriculum.
1. Molecules and molecular motion
(1) substance is composed of a large number of molecules.
If a molecule is regarded as a sphere, its diameter is only about 10- 10m. Therefore, the number of molecules in an object is huge.
At 0℃ and a standard atmospheric pressure, there are about 2.7× 10 19 molecules in the air of 1cm3. If you can count to 1000 billion per second, it will take 80 years to count all these molecules.
(2) Diffusion phenomenon
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Figure 1
As shown in figure 1, open a box of soap and you can smell the fragrance soon. Why?
What have we got in our noses?
Teacher: Some molecules with fragrance volatilize from soap, enter the air and travel in all directions. When they reach your nose, you will smell the fragrance.
As shown in fig. 2
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Figure 2
(1) Invert an empty bottle on a bottle filled with red-brown nitrogen dioxide gas, so that the two bottle mouths are opposite and separated by a glass plate, as shown in Figure 2. After the glass plate is removed, let the students observe what has happened.
(2) As shown in Figure 3, CuSO4 solution is injected into clean water and left for 30 days. Observe the phenomenon.
five years later
① Diffusion: The phenomenon that different substances enter each other when they contact each other.
② Description: Gas, liquid and solid can diffuse.
Conclusion: Diffusion phenomenon shows that the molecules of all substances are constantly moving irregularly, and there are gaps between them.
(4) examples of diffusion phenomenon
I: When you wear perfume, people around you can smell it.
Ⅱ: When I was in full bloom, bloom was everywhere;
Ⅲ: The coal caving edges turn black for a long time;
Ⅳ: When sugar is put in water, the water becomes sweet.
Teacher: Can we change a condition for the same diffusion experiment, so as to change the diffusion speed?
Teaching plan design of hot spot sports of physics molecules in senior three.
Key ability
Through the teacher's demonstration experiment, we can learn the knowledge about the interaction between molecules and cultivate students' scientific literacy of being willing to explore the micro-world and daily life. At the same time, make students realize that through the phenomenon of direct perception, they can know the facts that cannot be directly perceived.
Teaching objectives
1). You should know that matter is composed of molecules and atoms, and all molecules of matter are constantly moving irregularly.
2) Diffusion phenomenon can be understood and explained from the viewpoint of molecular thermal motion.
3). Know the interaction between molecules.
Teaching focus
thermal motion
Teaching difficulties
1). From a macro point of view, we can infer imperceptible facts by directly perceiving phenomena.
2) Explain the related phenomena from the viewpoint of molecular thermal motion.
Teaching preparation
Jar filled with nitrogen dioxide, empty jar, glass plate, beaker, red ink, water, rubber dropper, two lead posts and hook code, spring and rubber ball, multimedia courseware, etc.
teaching process
Main teaching process Teaching content Teachers' activities Students' activities log on to the excellent teaching platform before class, send preview tasks to complete the preview tasks of this class, and give feedback on the preview situation.
Create a situation
Interest introduction
[Story Synopsis]: Throwing bottles angrily inspires national prestige.
Xiang Jing won four gold medals.
19 15 after the official opening of the China Pavilion of the Panama International Expo, the poorly packaged Moutai sent by the poor and weak China government failed to attract the attention of the judges. The representative of our country used his quick wits to pick up a bottle of Moutai and pretended not to see it. The bottle fell to the ground with a bang and the pottery jar broke. Suddenly, the rich bouquet conquered the judges, and Moutai won the gold medal, making it famous all over the world.
How did this wine get into the guest's nose?
Topic on blackboard molecular thermal motion
(Design intention: Introduce stories to arouse students' enthusiasm and stimulate their interest in learning and thirst for knowledge. )
Students listen to stories.
Students discuss and communicate.
Second, explore
New knowledge:
(a), the composition of the material
[Setting Situation]: It turns out that this is related to the microscopic particles that make up substances that we can't see with the naked eye. Modern research has found that ordinary matter is composed of extremely tiny particles-molecules and atoms. Please look at the pictures. (Teacher shows pictures)
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Blackboard writing:
Ordinary matter is made up of molecules and atoms.
Courseware demonstration: Assuming that the molecule is spherical and its diameter is only tens of billions of meters, people usually measure it in units of 10- 10m. There are about 2.7×10/9 molecules in the air of 1cm3. At present, there are 654.38 billion+00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
Students observe and realize that ordinary matter is made up of extremely tiny particles-molecules and atoms.
Student experience: the molecular volume is particularly small; The number of molecules in an object is huge. Second, molecules.
thermal motion
1, diffusion
phenomenon
1, definition:
[Question]: So these countless molecules that make up an object, do you think they are moving or static?
[Transition] Students put forward different views on this. Next, we will verify whether the molecules are moving through experiments.
[Demonstration experiment]: (Tip for excellent teachers: Please open the material "Demonstration video: gas diffusion") We put an empty bottle upside down on a bottle filled with red-brown nitrogen dioxide gas and remove the glass plate covering the nitrogen dioxide bottle.
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Inspiration and guidance:
(1) The color of the air bottle has changed. What does this mean?
(2) The color in the nitrogen dioxide bottle becomes lighter? What is the reason?
(3) In the experiment, can nitrogen dioxide gas with density greater than air be placed at the top? Why?
[Description]: This experiment demonstrates a diffusion phenomenon. Can students define diffusion according to the phenomenon just now?
The teacher summed up the definition of diffusion:
[Summary and blackboard writing]: The phenomenon that different substances enter each other when they contact each other is called diffusion.
[Into Life]: In our daily life, gas diffusion is very common. Please give an example.
(Design intention: The real classroom is in life, so that physical knowledge can be well used in life. )
[Question]:
Different gases can enter each other, so will this happen between different liquids?
[Play video]:
1. Play the video of CuSO4 solution diffusion.
(Wonderful teaching tip: Please open the material "Demonstration video: liquid diffusion")
Shape merging format
Guidance: What do you mean by fuzzy interface?
[Play video]: Gold and lead spread.
(Wonderful teaching tip: Please open the material "Demonstration Video: Solid Diffusion")
Embedded brush
[Teacher-student summary]: Diffusion can occur among gas, liquid and solid, among which gas is the fastest.
(Design intention: Let students perceive the diffusion phenomenon of various situations, which is more vivid and concrete. Through the diffusion between gas, liquid and solid, it is realized that the essence of these phenomena is the random movement of molecules. ) discussion, conjecture and basis:
(1) molecules are moving, based on the fragrance of flowers.
(2) Molecules are static, based on the fact that if molecules are moving, the shapes of the constituent objects will change constantly.
Students observe and discuss experimental phenomena;
(1) The air bottle changed from colorless to colored, indicating that the following nitrogen dioxide molecules moved into the air bottle. (2) Nitrogen dioxide molecules and air molecules enter the object, making the density of nitrogen dioxide smaller and the color lighter.
(3) student discussion: No,
Nitrogen dioxide gas has a high density. If you put it on it, it will sink because of the weight.
Students think, discuss and summarize their answers in their own words.
For example:
(1) the smell of medicine in the hospital
(2) The flowers in the wall are fragrant outside the wall
(3) Smoking secondhand smoke, etc.
Look at the phenomenon and experience the diffusion between liquids.
Students think, discuss and answer: Explain that the molecules of copper sulfate solution and water move each other on the interface.
Students watch the video and realize that diffusion can also occur between solids.
2. The main factor affecting the diffusion rate-temperature.
3. Molecular thermal motion
[Question]:
Pickled pickles often take ten days and a half months to become salty, but when cooking, they become salty after adding salt for a few minutes, indicating that there is a diffusion speed. What are the factors that affect the diffusion speed?
【 Design Experiment 】 One beaker contains half a cup of hot water, and the other beaker contains the same amount of cold water. Drop two drops of red ink into two cups with a dropper and compare the diffusion of red ink in the two cups.
(Wonderful teaching tip: Please open the material "New knowledge explanation: the influence of temperature on diffusion")
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[Summary]: The main factor affecting the diffusion rate-temperature.
[Molecular thermal motion]: Because the motion of molecules is related to temperature, this random motion is called molecular thermal motion.
Blackboard writing: molecular thermal motion
【 apply what you have learned 】:
"The fragrance of flowers makes people know that it is suddenly warm, and the sound of magpies wearing trees makes people happy." For the previous sentence, it can be understood from the physical point of view that the aromatic molecules secreted by flowers accelerated, indicating that the ambient temperature at that time was sudden.
Design intention: It is a common method to infer the facts that cannot be directly perceived through the phenomenon of direct perception. ) discuss and put forward a conjecture: the temperature when cooking is much higher than the room temperature when pickling pickles, so the temperature may make the diffusion speed different.
Students go on stage to show the experimental process, and the teacher guides the students to tell the variables that need to be controlled in the experiment-the amount of water and ink.
Observation and summary:
Red ink spreads quickly in hot water. It shows that the higher the temperature, the more intense the random movement of molecules and the faster the diffusion.
Fill in the blanks: the action is raised. 4. The proliferation phenomenon shows that
[Summary of teachers and students] A large number of facts and experiments confirm that the diffusion phenomenon can explain:
(1), the molecules of all substances are constantly moving irregularly, which is also the reason for the diffusion phenomenon.
(2) There are gaps between molecules.
[Teacher emphasizes] "non-stop" means under any circumstances. Students analyze and communicate the problems explained by these phenomena. (3), intermolecular forces
1, there is gravity between molecules.
2. There is repulsion between molecules.
There is both attraction and repulsion between molecules.
4. The relationship between intermolecular force and the state of matter.
[Question]: (The teacher picks up a book) Since matter is composed of molecules and atoms, and molecules are constantly moving, why didn't the molecules of this book fly away, and finally the book disappeared?
[Observation experiment]: Lead blocks with smooth and clean surfaces are pressed together, and the hook code cannot be pulled open.
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