Chemistry paper 1

• Solids


  • Particles in fixed arrangements, vibrate around fixed positions, have little kinetic energy, strong forces between them
• Liquids


  • Particles slightly more widely spaced apart, not touching as much, have intermediate forces between them, vibrate more, don't have fixed positions
• Gases


  • Particles further apart, have large amounts of kinetic energy, not held in fixed position, have weak forces between them
• Conversions between states of matter

  • Melting (solid to liquid)
  • Freezing (liquid to solid)
  • Boiling/Evaporating (liquid to gas)
  • Condensation (gas to liquid)
• In a closed container, condensation and evaporation will be occurring simultaneously
• Diffusion


  The net movement of particles from an area of high concentration to an area of low concentration, down the concentration gradient, no energy required, a passive process
• Diffusion example


  • Ammonia and hydrochloric acid in a glass tube, form ammonium chloride ring
• Solute


  The solid which dissolves in a solvent
• Solvent


  The liquid in which the solute dissolves
• Solution


  The mixture of the solvent and solute
• Saturated solution


  One where you can't dissolve any more solute into the solvent
• Fundamental chemistry concepts


  • Atom
  • Element
  • Compound
  • Mixture
• Atom


  The smallest particle of a substance that can exist
• Element


  Contains only one type of atom, cannot be split by chemical means
• Compound


  Two or more elements chemically combined, cannot be separated back into constituent elements
• Mixture


  Contains two or more elements not chemically combined, can be separated into constituent components
• Pure substance


  Contains only one type of material, has a fixed boiling point
• Separation techniques


  • Filtration
  • Evaporation
  • Separating immiscible liquids
  • Simple distillation
  • Fractional distillation
  • Chromatography
• Filtration


  Separates an insoluble solute from a solvent
• Evaporation


  Separates a soluble solute from a solvent
• Separating immiscible liquids


  Uses a funnel to separate liquids that do not mix
• Simple distillation


  Separates liquids of different boiling points
• Fractional distillation


  Separates many liquids of different boiling points, like crude oil
• Chromatography


  Separates liquids of different solubilities
• Molecule


  Two or more atoms bonded together
• Structure of an atom

  • Nucleus contains protons and neutrons, surrounded by shells of electrons
• Proton


  Positive charge, mass of 1
• Neutron


  Neutral charge, mass of 1
• Electron


  Negative charge, very small mass
• Atomic number


  Number of protons in an atom
• Mass number


  Total number of protons and neutrons in an atom
• Isotopes


  Atoms of the same element with the same number of protons but different number of neutrons
• Calculating relative atomic mass


  Multiply each isotope's mass by its percentage abundance, add together, divide by 100
• Relative atomic mass


  Ratio of the average mass of an element compared to one atom of carbon-12
• Group number


  Number of electrons in the outer shell of an atom
• Period number


  Number of electron shells in an atom
• Group 0 (noble gases)


  • Unreactive due to full outer electron shells
• Periodic table regions


  • Metals on left, nonmetals on right, hydrogen at top
• Metallic properties


  • High melting/boiling points, good conductors, shiny, sonorous, malleable, ductile
• Nonmetallic properties


  • Dull, low melting/boiling points, brittle, form acidic oxides, gain electrons in bonding