internal energy and energy transfers

• What do particles in a solid do?

  Vibrate
• What do particles in a liquid do?

  Move around each other
• How do particles in a gas move?

  Extremely rapidly
• What type of energy do all particles have?

  Kinetic energy
• What type of forces do particles have between them?

  Intermolecular forces
• What do molecules contain?

  Chemical bonds
• What kind of energy is due to intermolecular forces and chemical bonds?

  Potential energy
• What is internal energy?

  Energy stored in a system by particles
• What is internal energy the sum of?

  Total kinetic and potential energy of particles
• What does the definition of internal energy include?

  Atoms and molecules
• What happens if we heat a solid?

  We increase the internal energy
• What do we call it when a solid turns into a liquid?

  Melting
• What happens if we continue to heat a liquid?

  We continue to increase internal energy
• What do we call it when a liquid turns into a gas?

  Boiling
• What happens if we cool a gas down?

  We reduce the internal energy
• What do we call it when a gas turns back to a liquid?

  Condensation
• What happens if we cool a liquid down further?

  We reduce the internal energy even more
• What do we call it when a liquid turns to a solid?

  Freezing
• What can sometimes turn directly into a gas?

  A solid
• What is it called when a solid turns directly into a gas?

  Sublimation
• What happens to mass when changes of state take place?

  Mass is always conserved
• Are changes of state physical or chemical changes?

  Physical changes
• If we reverse a change of state, what happens to the material?

  It recovers its original properties
• What is evaporation?

  When a liquid turns to a gas
• Where does evaporation occur?

  Only on the surface of a liquid
• During evaporation, which particles have enough energy to turn into a gas?

  Only the particles on the surface
• What type of energy is stored inside a system by its particles?

  Internal energy
• What two forms of energy does internal energy include?

  Kinetic and potential energy
• What causes the kinetic energy of particles?

  Their movement
• What causes the potential energy of particles?

  Forces between particles and bonds
• What happens to the temperature of a solid substance as it is gradually heated?

  The temperature rises
• On a heating graph, what does a horizontal line indicate?

  A change of state
• What is the specific change of state called when a solid turns into a liquid?

  Melting
• What happens to the energy being put in during a change of state?

  It weakens forces of attraction between particles
• What do scientists call the energy needed for a substance to change state?

  Latent heat
• What happens to the internal energy during a change of state?

  It increases
• What happens to the temperature during a change of state?

  It does not change
• What is the temperature at which a substance melts called?

  Melting point
• After all of the solid has melted into a liquid, what happens to the temperature as heating continues?

  The temperature starts to rise again
• On a heating graph, what happens when the temperature stops increasing and the line becomes horizontal again?

  The substance is boiling