Atoms

• Atoms


  • the smallest unit that makes up an element
  • consists of a nucleus, electron shells and sub-atomic particles : protons, neutrons and electrons)
  • number of protons equal to number of electrons
  • an atom is electrically neutral as the number of positively charged protons is balanced by an equal number of negatively charged electrons
• Nucleons

  • protons and neutrons
  • found in the nucleus
• Protons


  • relative mass of 1
  • relative charge of +1 (positive)
  • located in the nucleus
• Neutrons


  • relative mass of 1
  • relative charge of 0 (neutral)
  • located in nucleus
• electrons


  • relative mass of 1/1840 (negligible)
  • relative charge of -1 (negative)
  • located in the electron shell