Matter In Our Surroundings

Key Notes:

Definition of Matter

• Matter is anything that has mass and occupies space.
• It can be perceived through the senses.

Physical Nature of Matter

• Matter is made up of tiny particles.
• These particles are too small to be seen with the naked eye.

Characteristics of Particles of Matter

• Particles are continuously moving: They possess kinetic energy and move faster at higher temperatures.
• Particles have space between them: The space determines the state of matter (solid, liquid, or gas).
• Particles attract each other: The force of attraction varies among solids, liquids, and gases.

States of Matter

• Solids: Fixed shape and volume, strong intermolecular force, minimal particle movement.
• Liquids: Fixed volume, take the shape of the container, weaker intermolecular force compared to solids, particles can slide past each other.
• Gases: No fixed shape or volume, very weak intermolecular force, particles move freely and quickly.

Changes in States of Matter

• Effect of Temperature:
  • Increasing temperature increases the kinetic energy of particles, causing changes in state (solid to liquid to gas).
  • Melting point: Temperature at which a solid turns into a liquid.
  • Boiling point: Temperature at which a liquid turns into gas.
  • Sublimation: Some solids directly change into gas without becoming liquid (e.g., camphor, iodine).
• Effect of Pressure:
  • Increasing pressure can change a gas to a liquid by bringing particles closer.

Latent Heat

• Latent heat of fusion: Heat required to change 1 kg of a solid into a liquid without changing temperature.
• Latent heat of vaporization: Heat required to change 1 kg of a liquid into gas without changing temperature.

Evaporation

• Process of liquid changing into vapor at a temperature below its boiling point.
• Factors affecting evaporation:
  • Surface area: More area leads to faster evaporation.
  • Temperature: Higher temperature increases evaporation rate.
  • Humidity: Higher humidity decreases evaporation rate.
  • Wind speed: Faster wind increases evaporation.

Cooling Effect of Evaporation

• During evaporation, particles absorb energy from their surroundings, leading to a cooling effect (e.g., perspiration cools the body).