the atom

• what is an atom?

  smallest part of an element that can exist
• what is daltons model of the atom?

  atoms as solid spheres that could not be divided into smaller parts
• what is the plum pudding model of the atom?


  sphere of positive charge with negative electrons embedded in it
• what was the alpha scattering experiment?

  where alpha particles were fired at a thin layer of gold
• what were the results of the alpha scattering experiment?

  that when the alpha particles were deflected. this showed that the atoms mass and positive charge are concentrated at the mass of the atom - the nucleus
• describe the nuclear model of the atom

  dense nucleus with electrons orbiting it
• what did niels bohr discover?

  electrons orbit in fixed shells
• what did james chadwick discover?

  uncharged particle called the neutron
• where are protons and neutrons?

  nucleus
• what is the relative mass of each sun-atomic particle?

  proton: 1

  neutron: 1

  electron: 0
• why do atoms have no overall charge?


  Equal numbers of protons and electrons.
• what is an element?

  a substance made if one type of atom
• what is a compound?

  substance made if more than one type of atom chemically joined together
• what is a mixture?

  A combination of two or more substances that are not chemically bonded.
• what are isotopes?


  Atoms of the same element with different numbers of neutrons.
• what are the 4 physical processes that can be used to separate mixtures?

  filtration, crystallisation, distillation, chromatography
• what is filtration?


  Separation of solids from liquids using filtration paper
• what is crystallisation?


  The process of forming a solid crystal from a liquid or gas.
• what is simple distillation?

  Separation of liquids based on boiling points.
• what is fractional distillation?

  Separation of a mixture into its components based on their different boiling points.
• what is photo chromatography?

  separation of liquids