"Thermal Motion of Molecular" Heat and Energy PPT Courseware 4

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"Thermal Motion of Molecular" Heat and Energy PPT Courseware 4

Do you understand the scale of matter?

Light-years: The diameter of the Milky Way is approximately 100,000 light-years.

Kilometers: China has a vast territory, about 5,200 km from east to west and 5,500 km from north to south.

Meter: Yao Ming’s height is 2.26 m.

Millimeters: The smallest division of the student scale is 1 mm.

The scale of matter—Welcome to the microscopic world!

Micron: The diameter of a human hair is approximately 60 to 80 μm;

The length of a cell is approximately 10 μm;

The resolution limit of optical microscopy is 0.2 μm.

Nano: At this scale, we can count the number of molecules or atoms.

The diameter of a water molecule is 0.4 nm.

1. Composition of matter

Common substances are composed of extremely tiny particles-molecules and atoms.

How do you learn about the molecules that make up an object?

The conditions of the molecules constituting the object are inferred through some macroscopic manifestations of the object.

Matter is made of molecules

Substances have different _______ when they are in different states. The volume of most substances changes when they change from liquid to solid. When the state of a substance changes, the volume changes, mainly because the molecules that make up the substance change on ___________.

In solid substances, the forces between molecules are relatively ______, and their arrangements are relatively _____

Comparison of forces between gas molecules______Comparison of arrangements between molecules______

2. Thermal motion of molecules

1. diffusion

When different substances come into contact with each other, the phenomenon of entering each other is called diffusion.

Experimental observation 1

liquid diffusion phenomenon

Experimental Observation 2

liquid diffusion phenomenon

Diffusion phenomenon between solids

The corners where coal is piled up for a long time will turn black and cannot be swept clean with a broom.

A large number of facts such as diffusion phenomena show that the molecules of all substances are constantly moving irregularly.

2. molecular thermal motion

What factors determine the speed of movement of the molecules that make up matter?

The movement of molecules is related to temperature. The higher the temperature, the more violent the movement of molecules. We call the irregular motion of molecules thermal motion of molecules.

Explain the phenomenon: Why is it easier to smell the aroma of freshly fried hot dishes than cold dishes?

3. Intermolecular forces

1. There is both attraction and repulsion between molecules

Experiments show that there are both attraction and repulsion between molecules.

2. Macroscopic properties and microscopic description of solid, liquid, and gaseous substances

The distance between molecules determines the forces between molecules and thus the characteristics of solids, liquids and gases.

Gas molecules are very far apart and have almost no interaction with each other.

4. Molecular kinetic theory

1. Preliminary knowledge of molecular kinetic theory

Common substances are composed of molecules and atoms; the molecules in the substance are constantly undergoing thermal motion; there are attraction and repulsion forces between the molecules.

2. Summary of physical methods

We cannot observe the world of molecules, but we can obtain through experiments the fact that molecules are moving and that there are forces between molecules. Through direct perception of phenomena, we can infer facts that cannot be directly perceived. This is a commonly used method in physics.

practice

1. It can be seen from the picture that there are gaps between gold molecules under the electron microscope, so why is gold not easily compressed? How can you prove that there are gaps between molecules?

2. Xiao Ming saw that the weather report mentioned that inhalable particles are very small, so he thought, wouldn't it be good to use inhalable particles entering the air to illustrate that molecules are moving? He told this idea to Xiaoying, but Xiaoying said that his idea was wrong. Do you think Xiaoming's idea was right? If it is wrong, where is the mistake?

3． "A broken mirror cannot be reunited" is because when the glass is put back together, the distance between most of the molecules at the broken point of the mirror is too large, and there is almost no _________ between the molecules.

Class summary

Preliminary knowledge of molecular kinetic theory:

(1) Matter is composed of molecules;

(2) The molecules that make up matter are constantly undergoing thermal motion;

(3) There are attraction and repulsion forces between molecules.

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"Thermal Motion of Molecular Energy" PPT download:

"Molecular Thermal Motion" Internal Energy PPT Download Part One Content: Introductory Design Learning Point 1 Diffusion Phenomenon Experiment 1: On top of the bottle containing reddish-brown nitrogen dioxide gas, turn an empty bottle upside down so that the mouths of the two bottles face each other, with the middle Separate it with a glass plate, as shown in Figure 13-1.

"Thermal Motion of Molecular Energy" PPT:

"Thermal Motion of Molecular Energy" PPT Part One: Knowledge Management 1. Composition of Matter Common matter is composed of extremely tiny particles _____, _____. The diameter of a general molecule is only a few billionths of a meter, and people usually measure it in units of _____m..

"Thermal Motion of Molecular" Heat and Energy PPT Courseware 3:

"Thermal Motion of Molecular" Heat and Energy PPT Courseware 3 1. The composition of matter: *The molecules are very small, with a diameter of about 10-10m *The number of molecules is huge. Normally, there are about 2.71019 molecules in 1cm3 of air. If the speed of the number of people can To reach 10 billion per second, it takes...

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Update Time: 2024-10-04

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