Electrons

• Protons


  Subatomic particle with relative mass 1.000 and relative charge +1
• Neutrons


  Subatomic particle with relative mass 1.000 and relative charge 0
• Electrons


  Subatomic particle with relative mass 0.0005 and relative charge -1

  
• Atom


  • Protons and neutrons are found in the nucleus in the centre of the atom
  • Electrons are found in energy levels ("shells") around the nucleus

  
• Atomic Number


  The number of protons
• Mass Number


  The total number of protons and neutrons

  
• Since atoms are neutral, the number of electrons = number of protons
• Isotopes


  Atoms with the same number of protons but different numbers of neutrons
• Isotopes of hydrogen


  • One proton and one electron, but differ in how many neutrons they have
• In chemistry, isotopes behave identically because they have the same number of electrons
• Relative Atomic Mass (RAM)

  The average mass of an atom of an element, taking into account the different masses of each isotope

  
• Calculating Relative Atomic Mass (RAM)


  Using the mass numbers of each isotope and their %-abundances in nature