Matter in Our Surroundings 9 Science — Revision Notes
Matter is anything that has mass and occupies space, made up of atoms and molecules in constant motion. Understanding matter's properties helps us classify
TL;DR: Matter is anything that has mass and occupies space, made up of atoms and molecules in constant motion. Understanding matter's properties helps us cla…
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Matter is anything that has mass and occupies space, made up of atoms and molecules in constant motion. Understanding matter's properties helps us classify
States of Matter
- Solid: definite shape, definite volume, particles tightly packed, vibrate in fixed position
- Liquid: indefinite shape, definite volume, particles closely packed but free to move
- Gas: indefinite shape, indefinite volume, particles far apart, move randomly
Physical Properties of States
- Density increases from gas to liquid to solid
- Compressibility highest in gases, lowest in solids
- Intermolecular forces strong in solids, weak in gases
Changes of State
- Melting: solid to liquid at melting point (absorbs heat)
- Freezing: liquid to solid at freezing point (releases heat)
- Evaporation: liquid to gas (endothermic), boiling: rapid evaporation at boiling point
- Condensation: gas to liquid (exothermic)
- Sublimation: solid directly to gas without melting
Evaporation and Factors Affecting It
- Increased surface area increases evaporation rate
- Higher temperature speeds up evaporation
- Lower humidity and wind increase evaporation
- Evaporation is a cooling process
Key Terms
- Matter: Anything that has mass and occupies space
- Density: Mass per unit volume of a substance
- Melting Point: Temperature at which solid changes to liquid
- Boiling Point: Temperature at which liquid rapidly changes to gas
- Sublimation: Direct conversion of solid to gas without becoming liquid
Frequently Asked Questions
Why does water evaporate faster on a hot day?
Higher temperature provides more kinetic energy to water molecules, enabling them to overcome intermolecular forces and escape as vapor.
What is the difference between boiling and evaporation?
Evaporation occurs at any temperature from the surface, while boiling is rapid evaporation throughout the liquid at a specific temperature.
Can dry ice sublime at room temperature?
Yes, dry ice (solid CO2) sublimes at room temperature and atmospheric pressure, converting directly to carbon dioxide gas.
More 9 Science Revision Notes
- Is Matter Around Us Pure
- Atoms and Molecules
- Structure of the Atom
- The Fundamental Unit of Life
- Force and Laws of Motion
- Work and Energy
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