States of Matter

• What are the three states of matter?

  Solid, liquid, and gas
• What determines the state of matter of a substance?

  The forces between the particles
• What are the characteristics of solids?

  • Strong forces of attraction hold particles in fixed positions
  • Definite shape and volume
  • Particles vibrate about their positions
  • Expand slightly when heated
• How do solids behave when heated?

  They vibrate more and expand slightly
• What happens to a solid when it is heated sufficiently?

  It melts and becomes a liquid
• What are the characteristics of liquids?

  • Some force of attraction between particles
  • Do not keep a definite shape, but have a definite volume
  • Particles move with random motion
  • Expand slightly when heated
• How do liquids behave when heated?

  They move faster and expand slightly
• What happens to a liquid when it is cooled sufficiently?

  It freezes and becomes a solid
• What happens to a liquid when it is heated enough?

  It evaporates (or boils) and becomes a gas
• What are the characteristics of gases?

  • Next to no force of attraction between particles
  • Do not keep a definite shape or volume
  • Fill any container they are in
  • Move constantly with random motion
• How do gases behave when heated?

  They move faster and either expand or increase pressure
• What happens to a gas when it is cooled sufficiently?

  It condenses and becomes a liquid
• What are the limitations of the particle theory model?

  • Particles are not solid or spherical
  • Does not indicate the size of particles
  • Does not show the space between particles
  • Does not represent the forces between particles
• What is a physical change in terms of states of matter?

  A change where no new substances are made, like melting or freezing
• How can physical changes be reversed?

  By heating or cooling
• What occurs during a chemical reaction?

  Bonds between atoms break and atoms rearrange to form new substances
• What are the substances called that are present before a chemical reaction?

  Reactants
• What are the substances called that are formed after a chemical reaction?

  Products
• How do chemical changes compare to physical changes?

  • Chemical changes are often hard to reverse
  • Physical changes are easier to undo
  • Chemical changes involve the formation of new substances
  • Physical changes do not create new substances