ALL substances are made of particles.

Particles are too small to see without microscopes.

Probes have been developed that can sense forces between particles.

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  • Diffusion - The movement of particles in a gas or liquid from high to low concentration.
  • Molecules diffuse DOWN the concentration gradient. They become LESS concentrated.
  • High concentration is when there are a lot of the same particles near eachother, and low concentration is when they are more spread out.
  • When you can smell food coming from the kitchen, the particles are diffusing through the air from the kitchen and reaching where you are.
  • The particles do not consciously move to a lower concentration, this is the average movement over time. Particles move randomly.
  • Eventually, the particles will spread evenly through their container.
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