Atomic structure definitions

• atomic number


  the number of protons in the nucleus of an atom
• mass number


  the total number of protons and neutrons in the nucleus of an and
• Isotopes


  Same atomic which have the same atomic number but a diffrent mass number. They contain the same number of protons and different number of neutrons
• RAM


  Relative atomic mass of an element is the average mass of an atom of an element relaitive to 1/12th of the mass of an atom of carbon 12
• RMM


  Relative molecular mass is the average mass of a molecule relative to 1/12th of the mass of an atom of carbon 12
• RFM


  Relative formula mass is the average mass of a species relative to 1/12th of an atom of carbon 12
• Relative isotopic mass


  Mass of an an atom of an isotope of an element relative to 1/12th of the mass of an atom of carbon 12
• 1st ionisation energy


  This is the energy required to convert one mole of gaseous atoms into gaseous ions with a single positive charge
• 2nd ionisation energy


  This is the energy required to convert one mole of gaseous ions with a single positive charge into gaseous ions with a double positive charge
• Patterns of ionisation energies


  1 nuclear charge

  2 distance of the outer electron from the nucleus

  3 shielding by inner core of electrons

  4 stability of filled and half filled sub shells