chemistry paper one

• what is the structure of an atom like?


  nucleus - positive protons, neutral neutrons

  electron shells - negative electrons
• what do protons have the mass of?

  1
• what do neutrons have the mass of?

  1
• what do electrons have the mass of?

  mass too small to count
• what are the different models of atomic structure?


  earliest model = solid spheres

  JJ Thompson = plum pudding model - positive sphere with negative electrons

  Rutherford = modern model - added nucleus and electron shells
• what are isotopes?


  different atoms of the same element with a different number of neutrons
• what is the mass number?


  top number - total number of protons AND neutrons
• what is atomic number?


  the bottom number - number of neutrons
• what is relative atomic mass?

  the average mass of isotopes
• how to do you work out relative atomic mass?

  (% x mass) + (% x mass) / 100
• how does the periodic table organise the elements?

  horizontal groups (number of electrons in outermost shell) and vertical periods (number of shells)

  left-hand side = metals
• who created the first periodic table?

  Mendeleev
• what did mendaleev do that was special to his periodic table?

  left gaps for new elements to be discovered
• what is an ionic bond?

  bond between a metal and non-metal
• what is an ion?


  a charged particle - formed by the loss/gain of electrons
• what is a cation?

  postive ion (has lost electrons)
• what is an anion?


  negative ion (has gained electrons)
• what are the properties of a giant ionic lattice?


  lattice = regular structure

  strong electrostatic forces between ions
• what is a covalent bond?


  bond between non-metals - have a shared pair of electrons
• what are the properties of a covalent bond?


  strong forces between molecules

  weak intermolecular forces that can be overcome easily
• what is an alletope?

  giant covalent molecules - different structures containing the element in different patterns/shapes
• what are some examples of alletopes?

  carbon alletope - diamond + graphite
• what are the differences between diamond and graphite?

  diamond = hard, strong, pressure spread evenly across, cant conduct electricity

  graphite = layers that can slide (good lubricant), can conduct electricity
• why can graphite conduct electricity and diamond cant?

  graphite has delocalised (free) electrons and diamond doesnt
• what is a metallic bond?

  bond between metals
• what are the properties of metallic bonds?

  strong electrostatic forces, high melting point
• what is the relative formula mass?

  total mass of a compound
• what is the empirical formula?

  simplest ratio of all the numbers in a compound
• what are the properties of a solid?


  arranged in a fixed lattice, strong forces of attraction, low energy
• what are the properties of a liquid?

  random arrangement, more energy than a solid, move
• what are the properties of a gas?


  no shape, low forces of attraction, lots of energy
• what is melting?


  solid - liquid
• what is boiling?


  liquid - gas
• what is condensing?


  gas - liquid
• what is freezing?


  liquid - solid
• what is sublimation?


  solid - gas
• what is deposition?


  gas - solid
• what is a pure substance?

  an element made up only of that one element
• what is a mixture?

  lots of substances all mixed together
• what are the differences between a pure substance and a mixture?

  pure = fixed melting point