Expansion and Contraction

• The Kinetic Theory of matter - particles are always in random motion
• Diffusion - particles move from high concentration to a region of low concentration until evenly distributed
• When particles are heated, they gain energy and move around faster. This causes them to move further apart from other particles and causes expansion.
• When particles are cooled, they lose energy and move closer to one another, causing contraction of the object.
• contraction = cooling therefore, it moves closer together
• expansion = heating therefore, moves faster and further apart