Matter and Particle Theory Notes

Matter: A Closer Look at Particles

Definition of Matter

  • Matter is a physical substance.
  • It occupies space.
  • It has mass.
  • It holds or has energy within its particles.

Particle Theory of Matter

  1. All matter is made up of very small particles.
  2. All particles in a pure substance are the same; different substances are made up of different particles.
  3. There is space between all particles.
  4. The particles are always moving; as particles gain energy, they move faster.
  5. The particles in a substance are attracted to one another; the strength of the attractive force depends on the type of particle.

States of Matter and Particle Arrangement

The state of a substance depends on the arrangement of its particles:

  • Solid
    • Particles are held tightly.
    • Very close together.
    • Regular arrangement.
    • Particles vibrate but can't move from place to place.
  • Liquid
    • Particles are held weakly.
    • Very close together.
    • Random arrangement.
    • Particles vibrate and constantly move past each other.
  • Gas
    • No attraction between particles.
    • Far apart.
    • Random arrangement.
    • Particles vibrate and move quickly in all directions.

Classification of Matter

Matter can be classified into mixtures and pure substances.

Mixtures

Mechanical Mixtures
  • Contain a mixture of different types of particles.
  • They are heterogeneous.
  • Three types:
    • Ordinary mechanical mixtures
    • Suspensions
    • Colloids
Ordinary Mechanical Mixtures
  • Have the largest particles.
  • Particles stay mixed and do not separate on their own.
  • Examples: Granola, cookie dough
Suspensions
  • Particles are slightly smaller than ordinary mechanical mixtures.
  • Particles eventually separate out if the mixture is left to settle.
  • Example: Orange Juice
Colloids
  • Particles do not separate because they are so small that they stay suspended in the solvent.
  • If a light is shone through a colloid, it is scattered by the particles.
  • This would not happen with a solution.
  • Examples: Fog, milk
Solutions
  • Mixtures of solute and solvent.
  • Smaller particles than other mixtures and are homogeneous.
  • Solutions can include mixtures of solids, liquids, and gases.
  • Example: Salt Water

Pure Substances

  • Composed of identical particles.
  • Particles of different pure substances are different.
  • If these particles are broken down any further, the substance changes.
  • Example: Water is a pure substance but is made up of Oxygen and Hydrogen.
Categories of Pure Substances
  • Elements
    • Examples: Oxygen, Hydrogen
  • Compounds
    • Example: Water

Elements, Molecules, and Compounds

  • Some elements exist as individual atoms.
  • Often, elements consist of two or more atoms joined together; these are called molecules.
  • If more than one type of atom is in a molecule, it is called a compound.

Compounds

  • Pure substances that can be broken down into simpler substances.

Elements

  • Pure substances that cannot be broken down any further.