Chem Sect 2.3ABC, 2.4AB

• States of matter


  • Solid
  • Liquid
  • Gas
  • Plasma
• Model


  A representation that helps you better understand a concept
• All matter is made up of tiny particles (atoms) with empty space between them
• Particles are always moving
• Empty space and air space are not the same thing
• Solid


  • Molecules are packed very close together
  • Molecules are slowly but consistently vibrating
  • Molecules are attracted to each other
  • It has a fixed shape
  • It has a fixed volume
• Liquid


  • Molecules are further apart than in a solid
  • Molecules are constantly sliding past each other
  • There is less molecular attraction compared to solids
• Gas


  • Molecules are very far apart (lots of empty space)
  • Molecules are moving very quickly and freely
  • There is no attraction between molecules
  • It takes the shape of its container
  • It has a non fixed volume
• Kinetic molecular theory (KMT)


  • Atoms are always moving (kinetic energy)
  • Adding energy makes atoms move faster
  • When atoms move faster, they move further apart from each other
• Diffusion


  The movement of one material throughout another
• What happens on a molecular level when energy is added to matter

  1. Molecules move faster

  2. Molecules move further apart from each other
• If molecules move further apart

  The matter starts to take up more space
• Thermal expansion


  An increase in volume when matter is heated because the molecules have moved further apart from each other
• Thermal contraction


  A decrease in volume when matter loses energy because the molecules have moved closer together
• Changes of state


  • Melting (solid to liquid)
  • Evaporation (liquid to gas)
  • Sublimation (solid to gas)
  • Solidification (liquid to solid)
  • Condensation (gas to liquid)
  • Deposition (gas to solid)
• Thermometer


  A device used to measure temperature
• What happens on a molecular level when a thermometer is placed in hot water

  1. Fast moving molecules bump the glass molecules of the thermometer

  2. This bumping makes the glass molecules move faster and further apart

  3. This makes the alcohol in the thermometer move faster and expand

  4. As the liquid expands, it moves up the thermometer
• Temperature


  The average kinetic energy of molecules in a substance
• Thermal energy


  The total energy content of all molecules in a substance
• Democritus (460 BC) proposed that matter was made up of tiny particles that exist in empty space
• Aristotle (384 BC) disagreed with Democritus' idea of empty space
• John Dalton's (1766) experimental results supported the existence of atoms
• Dalton's atomic theory


  • All matter is made up of atoms
  • Atoms can not be created, destroyed or divided
  • Atoms of the same element have the same mass and chemical properties
  • In a chemical reaction, atoms are combined or rearranged
• J.J. Thomson (1856) discovered that atoms contain negatively charged particles (electrons)
• Ernest Rutherford (1871) discovered that atoms have a positively charged nucleus
• James Chadwick (1891) discovered that the nucleus contains neutral particles (neutrons)
• Niels Bohr (1885) discovered that electrons occupy specific energy levels (shells) around the nucleus
• Element


  The smallest particle of an element, made up of smaller subatomic particles (protons, neutrons, electrons)
• Nucleus


  The positively charged center of an atom, containing protons and neutrons
• Protons


  Positively charged particles found in the nucleus
• Neutrons


  Particles with no charge found in the nucleus
• Electrons


  Negatively charged particles found in the space surrounding the nucleus, arranged in energy levels
• Quarks


  Elementary particles that make up protons and neutrons
• Gluons


  Elementary particles that hold quarks together in protons and neutrons
• Leptons


  A type of elementary particle, including electrons
• Six types of quark flavors

  • Up
  • Down
  • Strange
  • Charm
  • Top
  • Bottom