Matter in Our Surroundings
Introduction to Matter
Everything around us is made up of matter. Matter is anything that has mass and occupies space. All living and non-living things are made up of matter.
Definition: Matter is defined as anything that occupies space, has mass, and can be perceived by our senses.
Characteristics of Particles of Matter
- Particles have space between them: The particles of matter have spaces between them. This is why we can dissolve sugar in water or compress gases.
- Particles are continuously moving: The particles of matter possess kinetic energy and are always in motion. The kinetic energy increases with temperature.
- Particles attract each other: There is a force of attraction between particles of matter which keeps them together. This force varies in different materials.
States of Matter
Matter exists in three main physical states:
1. Solid State
Properties of Solids:
- Have definite shape and volume
- High density
- Particles are very closely packed
- Particles have minimum kinetic energy
- Force of attraction is very strong
- Cannot be compressed
- Do not flow
2. Liquid State
Properties of Liquids:
- Have definite volume but no definite shape
- Take the shape of their container
- Density is less than solids but more than gases
- Particles are less closely packed than solids
- Can flow easily
- Cannot be compressed much
- Force of attraction is weaker than solids
3. Gaseous State
Properties of Gases:
- Have neither definite shape nor definite volume
- Lowest density
- Particles are far apart from each other
- Particles have maximum kinetic energy
- Force of attraction is negligible
- Highly compressible
- Flow easily in all directions
Change of State of Matter
Matter can change from one state to another by changing temperature or pressure.
Effect of Temperature
- Melting/Fusion: Change from solid to liquid (e.g., ice to water)
- Freezing/Solidification: Change from liquid to solid (e.g., water to ice)
- Vaporization/Boiling: Change from liquid to gas (e.g., water to steam)
- Condensation: Change from gas to liquid (e.g., steam to water)
- Sublimation: Direct change from solid to gas (e.g., dry ice, camphor)
- Deposition: Direct change from gas to solid
Latent Heat: The heat energy required to change the state of matter without changing its temperature is called latent heat.
Evaporation
Evaporation is the phenomenon of change of liquid into vapors at any temperature below its boiling point.
Factors Affecting Evaporation:
- Temperature: Evaporation increases with increase in temperature
- Surface Area: More surface area leads to faster evaporation
- Humidity: Less humidity in air increases evaporation
- Wind Speed: Higher wind speed increases evaporation
Note: Evaporation causes cooling because particles with higher kinetic energy escape, leaving behind particles with lower kinetic energy.
Important Terms
- Melting Point: The temperature at which a solid changes into liquid at atmospheric pressure
- Boiling Point: The temperature at which a liquid changes into gas at atmospheric pressure
- Kinetic Energy: The energy possessed by particles due to their motion
- Diffusion: The process of mixing of particles of two or more substances due to their motion
Multiple Choice Questions (MCQ)
Subjective Questions
Practice these questions to strengthen your understanding. Write your answers in the space provided.