chemistry

• Kinetic-molecular theory


  Explains the different properties of solids, liquids, and gases
• Kinetic-molecular theory


  • Atomic composition affects chemical properties
  • Atomic composition affects physical properties
  • Describes the behavior of matter in terms of particles in motion
• Gases


  • Consist of small particles separated by empty space
  • Particles are too far apart to experience significant attractive or repulsive forces
  • Particles are in constant random motion
• Elastic collision


  One in which no kinetic energy is lost
• Temperature


  Measure of the average kinetic energy of the particles in a sample of matter
• Compression of gases


  Reduces the empty spaces between particles
• Diffusion


  Movement of one material through another
• Effusion


  Gas escaping through a tiny opening
• Graham's law of effusion

  Rate of effusion for a gas is inversely proportional to the square root of its molar mass
• Pressure


  Force per unit area
• Barometer


  Instrument used to measure atmospheric air pressure
• Pascal


  SI unit of force, equal to a force of one Newton per square meter
• Atmosphere


  Unit of pressure, equal to 760 mm Hg or 101.3 kilopascals
• Dalton's law of partial pressures


  Total pressure of a mixture of gases is equal to the sum of the pressures of all the gases
• The partial pressure of a gas depends on the number of moles, size of the container, and temperature and is independent of the type of gas
• At a given temperature and pressure, the partial pressure of 1mol of any gas is the same
• Partial pressure can be used to calculate the amount of gas produced in a chemical reaction
• Polar covalent bond


  A type of bond that forms when electrons are not shared equally
• Dispersion force


  Weak force that results from temporary shifts in density of electrons in electron clouds
• Dipole-dipole force


  Attraction between oppositely charged regions of polar molecules
• Hydrogen bond


  Special dipole-dipole attraction that occurs between molecules containing hydrogen bonded to a highly electronegative atom
• Hydrogen bonds explain why water is a liquid at room temperature while compounds of comparable mass are gases
• Methane is nonpolar, so relatively weak dispersion forces holding the molecule together
• Ammonia and Water both form hydrogen bonds but oxygen is more electronegative than nitrogen making O-H bonds more polar and thus stronger
• The average kinetic energy of particles in a substance is measured by its temperature