Chapter 1-Matter in Our Surroundings

Physical Nature of Matter

MATTER IS MADE UP OF ==PARTICLES==
The particles of matter are ==very small== – they are small beyond our imagination!!!!

PARTICLES OF MATTER HAVE ==SPACE== BETWEEN THEM
PARTICLES OF MATTER ARE CONTINUOUSLY MOVING
The fact that matter particles are constantly in motion indicates that they have kinetic energy. Particles travel more rapidly as the temperature rises. Therefore, we can conclude that when temperature rises, so too does the kinetic energy of the particles.
PARTICLES OF MATTER ==ATTRACT== EACH OTHER
there is a force happening between the individual particles of matter. The particles are held together by this force. From one type of substance to another, this force of attraction has different strengths.

THE SOLID STATE-Intermolecular forces ==of attraction== are the ==highest== and ==intermolecular space== is ==negligible==.Solids are ==rigit and incompressible==
THE LIQUID STATE-We note that liquids have a defined volume but no set shape. The container in which they are stored determines their shape. Although they are not rigid, fluids can change shape and flow.==Intermolecular space is more than solids and intermolecular force of attraction is less than solids==
Liquids can diffuse solids, liquids, and gases. Compared to solids, liquids diffuse at a faster rate. This is because particles in the liquid state move more freely and have more room between them than those in the solid state do.
THE GASEOUS STATE-
Compared to solids and liquids, gases are very ==compressible==. Compressed gas is found in liquefied petroleum gas (LPG) cylinders that we purchase for use in our homes for cooking and in cylinders that deliver oxygen to medical facilities. Large volumes of a gas can be compressed into a compact cylinder and transported with ease due to its great compressibility. The particles in the gaseous state move ==rapidly and randomly==. The particles ==collide with one another and the container walls== as a result of this ==random movement==,the force that gas particles per unit area exert on the container walls is what causes the pressure that the gas is creating.

We all know from our observation that water can exist in three states of matter–

• Solid, as ice

• Liquid, as the familiar water

• Gas, as water vapour.

==The kinetic energy of the particles increase as the temperature of solids rises==.
The particles begin ==vibrating faster== as a result of the increase in kinetic energy.
The forces of attraction between the particles are ==defeated by the energy provided by heat==.
The particles start to move more freely after leaving their fixed places.A stage is reached when the solid melts and is converted to a liquid.

Change of a solid into a liquid when heat is applied is called melting.
The phase change of a substance from the liquid state to a solid-state is called freezing
When a liquid is heated to its boiling point, it quickly vaporises, which is known as boiling.

Applying pressure and reducing temperature can ==liquefy gases==.
DRY ICE- When the pressure is reduced to ==one atmosphere==, solid CO2 is immediately transformed to a gaseous state ==without first entering a liquid state==. Because of this, solid carbon dioxide is also referred to as dry ice.
Thus, we can say that pressure and temperature ==determine the state of a substance==, whether it will be solid, liquid or gases.
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(Boiling is a bulk phenomenon)

==If the surface area is increased, the rate of evaporation increases.== For example, while putting clothes for drying up we spread them out.
A rise in temperature: with a rise in temperature,more particles have enough kinetic energy to enter the vapour state as a ==result of rising temperatures so rate of evaporation increases==
A drop in humidity: The amount of water vapour in the air is referred to as humidity. At a specific temperature, the air surrounding us can only carry a certain amount of water vapour. ==The rate of evaporation slows down if there is already a lot of water in the air(humidity).==
A rise in wind speed: It is a well-known phenomenon that clothes dry more quickly on windy days. Humidity drops as a result of the water vapour particles being carried away by the wind as wind speed increases ,==also rate of evaporation is directly proportional to increase in wind speed.==
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The liquid keeps on evaporating in an open jar.
To make up for the energy lost during evaporation, the liquid particles take energy from their surroundings. The environment becomes cold due to this energy absorption from the surroundings.

Sublimation- Sublimation is the change of solid state directly to gaseous state without going through liquid state.
Deposition- Deposition is the change of gaseous state directly to solid state without going through liquid state.
Latent heat of vaporisation- Latent heat of vaporisation is the heat energy required to change 1 kg of a liquid to gas at atmospheric pressure at its boiling point.
Latent heat of fusion- Latent heat of fusion is the amount of heat energy required to change 1 kg of solid into liquid at its melting point.

Note

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