STATE OF MATTER
Science
INTRODUCTION
Matter is anything that has mass and occupies space. Everything around us – air, water, soil, living beings, metals – is made up of matter. Matter exists in different physical forms known as states of matter, depending upon temperature, pressure and intermolecular forces.
CLASSICAL STATES OF MATTER
Traditionally, matter exists in three basic states:
1. Solid
2. Liquid
3. Gas
1. SOLID STATE
Characteristics:
• Solids have a definite shape and definite volume.
• Particles are very closely packed.
• Intermolecular forces are very strong.
• Particles can only vibrate about their fixed positions.
• Solids are rigid and generally incompressible.
• Density is usually high.
Examples:
Iron, wood, stone, ice, salt, sugar.
Types of Solids:
(a) Crystalline Solids:
• Particles arranged in a regular and repeating pattern.
• Sharp melting point.
• Examples: salt, diamond, quartz, sugar.
(b) Amorphous Solids:
• Particles arranged irregularly.
• No definite melting point.
• Behave like supercooled liquids.
• Examples: glass, rubber, plastic.
2. LIQUID STATE
Characteristics:
• Liquids have a definite volume but no definite shape.
• They take the shape of the container.
• Intermolecular forces are weaker than solids but stronger than gases.
• Particles can slide over each other.
• Liquids can flow.
• Slightly compressible.
Examples:
Water, milk, oil, petrol, alcohol.
Properties of Liquids:
• Fluidity – ability to flow.
• Viscosity – resistance to flow.
• Surface tension – tendency of liquid surface to shrink.
• Diffusion – mixing of liquid particles.
3. GASEOUS STATE
Characteristics:
• Gases have neither definite shape nor definite volume.
• They occupy the entire space of the container.
• Intermolecular forces are negligible.
• Particles move freely at high speed.
• Highly compressible.
• Low density.
Examples:
Oxygen, nitrogen, carbon dioxide, hydrogen.
Properties of Gases:
• High diffusibility.
• Exert pressure on container walls.
• Expand rapidly on heating.
INTERCONVERSION OF STATES OF MATTER
Matter can change from one state to another by changing temperature or pressure.
1. Melting (Fusion):
Solid → Liquid
Example: Ice → Water
Melting point: Temperature at which solid changes to liquid at atmospheric pressure.
2. Freezing (Solidification):
Liquid → Solid
Example: Water → Ice
3. Evaporation:
Liquid → Gas (at any temperature below boiling point)
Example: Water evaporating from clothes.
Factors affecting evaporation:
• Surface area
• Temperature
• Wind speed
• Humidity
4. Boiling:
Liquid → Gas (at fixed temperature)
Boiling point: Temperature at which vapour pressure equals atmospheric pressure.
5. Condensation:
Gas → Liquid
Example: Water vapour → Water droplets.
6. Sublimation:
Solid → Gas directly without becoming liquid.
Example: Camphor, naphthalene, dry ice.
LATENT HEAT
Latent heat is the heat energy absorbed or released during change of state without change in temperature.
Types:
• Latent heat of fusion – solid to liquid.
• Latent heat of vaporisation – liquid to gas.
EFFECT OF PRESSURE ON STATES OF MATTER
• Increasing pressure can convert gases into liquids.
• Liquids can convert into solids under very high pressure.
• Example: LPG is stored in liquid form under high pressure.
KINETIC THEORY OF MATTER
Main postulates:
• Matter is made up of very small particles.
• Particles are in constant motion.
• There are spaces between particles.
• Particles attract each other.
MODERN STATES OF MATTER
1. PLASMA
• Ionised gas containing free electrons and ions.
• No definite shape or volume.
• Conducts electricity.
• Found at very high temperatures.
Examples:
Sun, stars, lightning, neon signs.
2. BOSE–EINSTEIN CONDENSATE (BEC)
• Formed at extremely low temperatures close to absolute zero.
• Particles lose individual identity and behave as a single entity.
• Shows quantum effects at macroscopic level.
Example:
Atoms cooled in laboratory experiments.
3. SUPERCRITICAL FLUID
• State above critical temperature and pressure.
• Shows properties of both liquid and gas.
• Used in decaffeination of coffee and extraction processes.
PDF File:
No PDF attached
Subject: Science
← Back