Chemistry C1 retrieval questions

• Atom

  Smallest part of an element that can exist
• Dalton's model of the atom

  Atoms as solid spheres that could not be divided in smaller parts
• Plum pudding model of the atom

  Sphere of positive charge with negative electrons embedded in it
• Alpha scattering experiment

  • Some alpha particles were deflected by the gold foil
  • This showed that an atom's mass and positive charge must be concentrated in one small space (the nucleus)
• Nuclear model of the atom

  Dense nucleus with electrons orbiting it
• Niels Bohr

  • Discovered electrons orbit in fixed energy levels (shells)
• James Chadwick

  • Discovered the uncharged particle called the neutron
• Location of protons and neutrons

  In the nucleus
• Relative mass of sub-atomic particles

  Proton: 1, neutron: 1, electron: 0 (very small)
• Relative charge of sub-atomic particles

  Proton: +1, neutron: 0, electron: -1
• Finding the number of protons in an atom

  The atomic number on the Periodic Table
• Calculating the number of neutrons in an atom

  Mass number - atomic number
• Atoms have no overall charge because they have equal numbers of positive protons and negative electrons
• Electron shell configuration

  Require up to 2 in the first shell and up to 8 in the second and third shells
• Element

  Substance made of one type of atom
• Compound

  Substance made of more than one type of atom chemically joined together
• Mixture

  Two or more substances not chemically combined
• Isotopes

  Atoms of the same element (same number of protons) with different numbers of neutrons
• Physical processes to separate mixtures

  • Filtration
  • Crystallisation
  • Distillation
  • Fractional distillation
  • Chromatography
• Relative mass

  The average mass of all the atoms of an element