Specification Point 1.1:
Understand the three states of matter in terms of the arrangement, movement & energy of the particles
Particles in a Solid
Particles in a solid
Arrangement:
- Regular repeating pattern
- Close together, touching each other
Movement:
- Vibrate about fixed positions but do not move apart
Forces between particles:
- Stronger than in a liquid
Shape:
- Fixed shape and volume
Particles in a Liquid
Particles in a liquid
Arrangement:
- Irregular
- Close together and touching each other
Movement:
- Move around and slide past one another
Forces between particles:
- Not as strong as solid
Shape:
- No fixed shape (takes shape of container) but fixed volume
Particles in a Gas
Particles in a gas
Arrangement:
- Irregular
- Far apart
Movement:
- Move freely and collide with each other
Forces between particles:
- Non-existent
Shape:
- No fixed shape or volume
Specification Point 1.2:
Understand the interconversions between the three states of matter in terms of:
– the names of the interconversions
– how they are achieved
– the changes in arrangement, movement & energy of the particles
Interconversion Names & Definitions
Melting the process of converting from solid to liquid due to increase in temperature.
Melting point the temperature at which a solid starts to melt, eg. ice melts at 0 °C.
Boiling the process of converting from liquid to gas due to increase in temperature. Also known as vaporisation.
Boiling point the temperature at which a liquid starts to boil, eg. water boils at 100 °C.
Condensation the process by which a gas turns to liquid.
Sublimation the process by which a solid turns directly to gas without melting.
Solidification the process by which a gas turns directly to solid.
Evaporation the process by which a liquid turns to a gas below its boiling point.
Volatile liquids that evaporate at room temperature.
Interconversions of solids, liquids and gases
Arrangement, Movement & Energy
Solid to Liquid
Heat solid until it melts. When a solid is heated the particles gain kinetic energy and start to vibrate faster about their fixed position. When the temperature is high enough, the vibration of particles becomes sufficient to overcome the forces of attraction between them. The particles begin to break away from their regular pattern. They can now slide past each other. The solid becomes a liquid.
Liquid to Solid
Cool liquid until it freezes. When a liquid is cooled, the particles lose their kinetic energy. When the temperature is low enough, the particles no longer have the energy to slide over each other. The forces of attraction can hold the particles together in a regular pattern. The substance becomes solid.
Liquid to Gas
Heat the liquid until it boils. When a liquid is heated, the particles gain kinetic energy and mover further apart. Eventually, the attractive forces in the liquid are broken. Bubbles of gaseous particles escape from the liquid. The substance becomes gas.
Gas to Liquid
Cool the gas until it condenses. When a gas is cooled, the particles lose kinetic energy and the attractive forces become great enough to keep the particles closer together as a liquid.
Solid to Gas
Heat the solid until it sublimes. The solid particles gain kinetic energy and vibrate faster. Eventually, the forces of attraction between the particles are completely broken and they escape from the solid as a gas.
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Author: Jamie
Jamie got a First class degree in Chemistry from Oxford University before going on to teach chemistry full time as a professional tutor. He’s put together these handy revision notes to match the Edexcel IGCSE Chemistry specification so you can learn exactly what you need to know for your exams.
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