Module 2.1.1 & 2.1.2- Atomic structures, isotopes, compounds, formulae and equations

• Isotopes


  Atoms of the same element that have different numbers of neutrons and different masses
• Atomic structure


  Electron on outer shell, neutron and proton in center nucleus

  
• Relative isotopic mass


  The mass of an atom of an isotope compared with 1/12 of the mass of an atom of carbon-12
• Relative atomic mass


  The weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of carbon-12
• Mass spectrometer


  an instrument used to measure the precise masses and relative amounts of atomic and molecular ions

  
• Relative atomic mass formula


  Sum of (isotope abundance x isotope mass number) / sum of abundances of all the isotopes

  
• Recall the 4 common anions


  NO3 -, CO3 2-, SO42 -, OH-
• Recall the 3 common cations

  NH4 +, Zn 2+, Ag +
• How to balance chemical equations

  Example:____ NH3 + ____ I2 → ____ N2I6 + ____ H2 _2NH3 + 3I2 → N2I6 + 3H2amount of atoms of each element has to = on both sides

  
• How to construct ionic equations


  Write out the balanced equation

  Rewrite equation in the form of ions on both sides

  Cancel out ions seen on both sides (spectator ions) Ions left is the ionic equation