Characteristics of Particles (Molecules) of Matter

1. Particles of matter have space between them

Particles of one type of matter get into the spaces between particles of the other. This shows that there is enough space between particles of matter.

2. Particles of matter are continuously moving

Particles of matter are continuously moving as they have kinetic energy. With the increase in temperature, the kinetic energy of the particles also increases and particles move faster.

3. Particles of matter attract each other

Particles of matter have a force acting between them. This force keeps the particles together. The strength of this force of attraction varies from one kind of matter to another

From the above figure, it is obvious that it would be easier to break a piece of chalk than the iron ball. This is because the particles in the iron ball are held together with greater force than that of the chalk.

1. Solids: Particles are very close together, vibrating in fixed positions. This gives solids a definite shape and volume, high density, and makes them non-compressible.
2. Liquids: Particles are still close but can move past each other. The intermolecular force is moderate, allowing liquids to have a definite volume but no fixed shape, taking the shape of their container. Liquids also have fluidity.
3. Gases: Particles are far apart with very weak intermolecular forces, moving freely and occupying all available space. Gases have no definite shape or volume.

Physical state of matter: submicroscopic picture

Classification by Composition

Matter can be classified into elements, compounds, and mixtures based on the type of smallest particles:

1. Element: Made of identical atoms (e.g., an oxygen molecule, O₂, has two identical oxygen atoms).
2. Compound: Made of different atoms bonded together (e.g., a water molecule, H₂O, has two hydrogen atoms and one oxygen atom).
3. Mixture: Contains a combination of different atoms or molecules (e.g., air has N₂, O₂, CO₂, etc.; brass is a mix of copper and zinc atoms).

1. Aim: To observe how energy affects the movement of particles, similar to how particles behave in solid, liquid, and gaseous states.

2. Requirements: mustard seeds, a transparent plastic jar, a large balloon, a long thread, a needle, and a rubber band.

3. Procedure:

• Take some mustard seeds and place them in a transparent plastic jar.
• Thread a long thread through the centre of a large balloon using a needle and tie it securely.
• Stretch the balloon over the mouth of the jar, creating a rubber diaphragm, and fix it with a rubber band.

Movement of mustard seeds

4. Conclusion: The movement of mustard seeds changes depending on how much energy is applied. This demonstrates how particles in solids, liquids, and gases move differently based on the energy they receive and the intermolecular forces acting between them.