Kinetic Theory of Matter

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Kinetic Theory of Matter

• SCI 201

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Driving Questions

• What is the kinetic theory of matter and how does
  it explain the nature of solids, liquids, and
  gases?
• How can heat and temperature be distinguished
  from one another?
• What simple phenomena can be explained by the
  kinetic theory of matter?

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Kinetic Theory of Matter

• Matter can be thought of as being composed of
  tiny particles (called molecules) in constant
  random jiggling motion attracting each other
  when they are a little distance apart, but
  repelling each other upon being squeezed into one
  another
• The molecules of fluids can be thought of as
  billiard balls that undergo collisions with each
  other and the walls of their containers
• Molecules definition the smallest unit of a
  substance that can exist alone and retain the
  character (i.e. physical and chemical properties)
  of that substance

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Solids, Liquids, and Gases

• Solids have a definite shape and volume
• Liquids have a definite volume but assume the
  shape of their container
• Gases assume the shape and volume of their
  container

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What are heat and temperature?

• Temperature is a measurement of the average mass
  and speed (called kinetic energy) of molecules in
  a substance - the higher the average molecular
  motion of the particles, the higher the
  temperature
• Heat is energy in transit (meaning as the energy
  is transferred from one body to another)

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Add some heat energy

• The jiggling increases and the space between the
  molecules increases if enough heat is added, the
  attraction is not enough to hold them together so
  they fly apart and become separated from one
  another
• Thus a gas is formed

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Remove heat energy from the liquid instead

• The jiggling decreases soon the forces of
  attraction take over and the molecules cant
  jiggle so well
• Soon there is a definite place for every atom a
  rigid structure of interconnectedness is formed
• Thus the liquid becomes a solid which has a
  structure called a crystalline array

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Most substances

• Expand when heated and contract when cooled
• Water is an exception think about what happens
  to a can of soda when it is put into a freezer
  for rapid cooling
• NOTE Water does behave like other substances
  between 0 and 4 Celsius

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Using the theory

• Balloon in the jar
• Burning paper in a jar
• Revisiting Bernoulli
• The paper tent
• The ping-pong balls

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Driving Questions

• What is the kinetic theory of matter and how does
  it explain the nature of solids, liquids, and
  gases?
• How can heat and temperature be distinguished
  from one another?
• What simple phenomena can be explained by the
  kinetic theory of matter?