Atomic structure and the periodic table

• Define atom

  The smallest part of an element that can exist
• Compare the plum pudding model to the nuclear model of the atom

  Both have positive charge (plum pudding in a ball, nuclear in nucleus)

  Both have electrons (plum pudding randomly spread, nuclear in shells)

  Nucelar has a nucleus and neutrons
• Define compound

  Compounds contain two or more elements chemically combined
• State the 3 subatomic particles and give their charge and relative masses

  Particle - Charge - Mass

  Proton - +1 - 1

  Neutron - 0 - 1

  Electron - -1 - very small
• Define mixture

  Two or more elements or compounds not chemically combined
• How do you calculate the number of neutrons in an atom?

  Mass number - atomic number
• Name 5 methods of separating mixtures

  Filtration, crystallisation, simple distillation, fractional distillation and chromatography
• Describe the plum pudding model of the atom (now proved wrong)

  The atom is a ball of positive charge with negative electrons embedded in it
• What are the vertical columns of the periodic table called?

  Groups
• Describe the experiment that led to the new model of the atom

  The alpha particle scattering experiment - Most particles went straight through = empty space

  Some deflected a little = positive centre

  Some deflected back = large mass at centre
• Why are atoms in the same group similar?

  They have the same number of electrons in their outer shell / orbit
• Who is responsible for the modern periodic table?


  Dmitri Mendeleev
• What is Mendeleev‘s key innovation in making this table?

  He left gaps for undiscovered elements and changed the order in some places based on weights