States of Matter
Matter exists mainly as solid, liquid, or gas. Particle arrangement and motion differ in each state, but particles themselves do not change.
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Particle view of matter
In the particle model, matter is made of tiny particles (atoms or molecules) separated by empty space. In a solid, particles are closely packed in fixed positions and can only vibrate about their mean positions. In a liquid, particles are still close but can slide past one another. In a gas, particles are far apart and move randomly in all directions.
Energy and spacing
On average, gas particles have more kinetic energy than liquid particles at the same temperature; liquid particles have more than solids. As you go from solid → liquid → gas, average spacing between particles increases and the strength of intermolecular forces typically decreases.
How does the motion of particles in ice differ from those in liquid water and in steam?