*Molecular movements* refer to the various ways molecules move, vibrate, or rotate, depending on their state of matter (solid, liquid, gas) and temperature. These movements are fundamental in understanding physical properties, chemical reactions, and diffusion.

Types of Molecular Movements:

1. *Translational Motion*

- Molecules move from one place to another in space.

- Most noticeable in *gases*.

- Example: Gas molecules spreading out in a room.

2. *Rotational Motion*

- Molecules rotate around their axes.

- Happens in *gases and liquids*.

3. *Vibrational Motion*

- Atoms within a molecule oscillate (vibrate) around their equilibrium positions.

- Common in *solids, liquids, and gases*, especially at higher temperatures.

- Example: Stretching and bending of chemical bonds.

4. *Brownian Motion*

- Random movement of particles suspended in a fluid due to collisions with molecules.

- Observed under a microscope with tiny particles in water.

5. *Diffusion*

- Molecules move from areas of *high concentration to low concentration*.

- Driven by molecular kinetic energy.

*Temperature effect:*

- Higher temperature → faster molecular movement.

- Lower temperature → slower movement, molecules vibrate less.

2 hours ago, Adiel Barnabe João Quinan said:

*Molecular movements* refer to the various ways molecules move, vibrate, or rotate, depending on their state of matter (solid, liquid, gas) and temperature. These movements are fundamental in understanding physical properties, chemical reactions, and diffusion.

Types of Molecular Movements:

1. *Translational Motion*

- Molecules move from one place to another in space.

- Most noticeable in *gases*.

- Example: Gas molecules spreading out in a room.

2. *Rotational Motion*

- Molecules rotate around their axes.

- Happens in *gases and liquids*.

3. *Vibrational Motion*

- Atoms within a molecule oscillate (vibrate) around their equilibrium positions.

- Common in *solids, liquids, and gases*, especially at higher temperatures.

- Example: Stretching and bending of chemical bonds.

4. *Brownian Motion*

- Random movement of particles suspended in a fluid due to collisions with molecules.

- Observed under a microscope with tiny particles in water.

5. *Diffusion*

- Molecules move from areas of *high concentration to low concentration*.

- Driven by molecular kinetic energy.

*Temperature effect:*

- Higher temperature → faster molecular movement.

- Lower temperature → slower movement, molecules vibrate less.

What do you want to discuss?

The core reason for molecular motion lies in its own kinetic energy, which manifests as thermal motion and is the fundamental driving force for molecules to constantly move irregularly.

Specifically, molecular motion is mainly driven by the following factors:

Thermal energy drive: Temperature is a sign of the average kinetic energy of molecules. The higher the temperature, the more intense the molecular thermal motion, the faster the speed, and the higher the collision frequency.

Intermolecular forces: There are both attractive and repulsive forces between molecules. When molecules approach each other, repulsion dominates; When moving away, gravity dominates. This interaction force causes molecules to constantly adjust their distance during motion, forming a dynamic equilibrium.

Energy conversion: The continuous conversion between molecular kinetic energy and potential energy. For example, when gas molecules move in a container, their kinetic energy and potential energy continue to convert, maintaining irregular motion.

It should be noted that molecular motion does not violate the law of conservation of energy. Its energy comes from the internal energy of the system itself, rather than continuous external input, so it is fundamentally different from a perpetual motion machine.

54 minutes ago, allenlee888 said:

When molecules approach each other, repulsion dominates; When moving away, gravity dominates.

This is not correct. As neutral molecules approach each other, there is attraction until the atoms try to get within each other's atomic radii, then there is a sharp repulsion. Also, gravity is too weak to be significant in intermolecular interactions. Intermolecular interactions are electromagnetic in character. Even for uncharged molecules without permanent dipoles, transient induced dipoles called "London forces" result in attraction between molecules.

5 hours ago, allenlee888 said:

The core reason for molecular motion lies in its own kinetic energy, which manifests as thermal motion and is the fundamental driving force for molecules to constantly move irregularly.

Specifically, molecular motion is mainly driven by the following factors:

Thermal energy drive: Temperature is a sign of the average kinetic energy of molecules. The higher the temperature, the more intense the molecular thermal motion, the faster the speed, and the higher the collision frequency.

Intermolecular forces: There are both attractive and repulsive forces between molecules. When molecules approach each other, repulsion dominates; When moving away, gravity dominates. This interaction force causes molecules to constantly adjust their distance during motion, forming a dynamic equilibrium.

Energy conversion: The continuous conversion between molecular kinetic energy and potential energy. For example, when gas molecules move in a container, their kinetic energy and potential energy continue to convert, maintaining irregular motion.

It should be noted that molecular motion does not violate the law of conservation of energy. Its energy comes from the internal energy of the system itself, rather than continuous external input, so it is fundamentally different from a perpetual motion machine.

This is a discussion forum. Nobody here is in need of a bad lecture on kinetic theory. What do you wish to discuss?