chapter 2 - atoms ions and compounds

• a proton is virtually the same mass as a neturon

  a electron has a negligible mass of 1/1836
• a proton has relative 1+ charge

  an electron has relative 1- charge
• the overall charge of an atom is zero

  an atom is neutral
• atomic number = number of protons
• isotopes are atoms have the same element with different numbers of neutrons and different masses
• mass number = number of protons + number of neutrons
• representing isotopes


  e.g isotopes of carbon:

  carbon-12 carbon-13
• carbon-12 (C-12) : 6 protons, 6 electrons, 6 neutrons
• carbon-13 (C-13): 6 protons, 6 electrons, 7 neutrons
• the number of neutrons have no affect on a chemical reaction
• cations


  positive ions
• anions


  negative ions
• 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.
• relative isotopic mass


  the mass of an isotope relative to 1/12th of the mass of an atom of carbon-12
• using a mass spectrometer

  1. sample is placed on mass spectrometer
  2. sample is vaporised, then ionised to form positive ions
  3. ions are accelerated, heavier ions move more slowly, and are more difficult to deflect than lighter ions
  4. the ions are detected on the mass spec, as a mass to charge ratio
• mass to charge ratio (m/z)


  relative mass of an ion/relative charge on ion
• a binary compound contains 2 elements only
• naming a binary compound


  use the name of the first element, change the ending of the second to -ide
• polyatomic ion are ions with more than one element bonded together