Particle Theory

Particle Theory

Basic Principles

  • All matter is made up of tiny particles.
  • Each type of material has a unique type of particle or mixture of particles.
  • These particles are in constant, random motion.
  • The higher the temperature, the faster they move.

Arrangement and Movement of Particles

  • Particles of solids are arranged in fixed positions in a tight, regular pattern.
  • They vibrate around a fixed point but do not change position.
  • Liquid particles are not arranged as tightly as in solids, allowing them to slide over each other, explaining the fluid property.
  • Gas particles have the most space and freedom and move all over the place in all directions.

Changes of State

  • Adding or removing heat causes materials to change states.
  • When a solid is heated, its particles vibrate more until they break free from their fixed positions and start sliding over each other. This is the process of melting.
  • When a liquid is cooled, its particles begin to vibrate less and get closer together, forming a solid. This is the process of freezing.
  • When a liquid is heated, its particles move faster and spread out to become a gas. This is the process of evaporation.
  • When a gas is cooled, its particles slow down and come together to form a liquid. This is the process of condensation.

Density

  • The density of an object is determined by the amount of particles in a given space.
  • More densely packed particles result in a denser object.
  • Density can be calculated using the formula: density = mass/volume.

Diminishing Particle Size and Surface Area

  • The smaller the particles, the larger the exposed surface area.
  • Larger surface area leads to faster rates of reaction because there are more opportunities for the substance to interact.

Diffusion

  • Diffusion is a process where particles spread, mixing with each other without any external influence.
  • Particles in a gas diffuse fastest due to the maximum space and freedom, followed by liquid and then solid.