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Particle theory

Reflections and Exam tips


What's the Matter?

All things around us are made up of matter. Matter is what things are made up of.

Look around and think of everyday things: All things that you can think of are either a Solid, Liquid or a Gas. These are called the 3 states of matter.

Solids, liquids and gases (matter) are made up of particles. We can think of particles as tiny bits (circles) which are grouped together to make matter. In science, particles are either atoms or molecules (groups of atoms). Particles can also be smaller sub-atomic particles like electrons, neutrons and protons.

The 3 states of matter

Solid matter

Solids are solid matter. We all know what the term solid means but it can be rather difficult to explain. Thinking of solids in terms of particles makes it easier to explain this term:

Particles in a Solid, Liquid and Gas

Comparing Solids, Liquids and gases

  Solid Liquid Gas
Arrangement of particles Fixed, regular pattern Random Random
Spaces Very small spaces between particles Some spaces Very far apart
Kinetic energy (movement) Only vibrate, can not move Can flow Freely move
Bonding Particles held together tightly Weak bonds hold particles No bonds, free movement
Shape Fixed shape, can not be compressed, particles are already touching each other. Can change shape to fit container- can be compressed only slightly as there are small spaces between particles. No shape, can be compressed into a small container- becaue particles are far apart.


Changing state

When a a substance changes state, the arrangement of particles and the kinetic energy of the particles also change.

Changes of state are Physical changes- no new substance is formed and they are reversible.

Changes of state