Specification Point 1.1:
Understand the three states of matter in terms of the arrangement, movement & energy of the particles

Particles in a Solid

States of Matter: 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, IGCSE Chemistry revision notes

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, States of matter

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.

Interconversion between states of matter

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.

Need help?

Aiming for a Level 9?

See if you’ve got what it takes. Test yourself with our topic questions.

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.