The Periodic Table

• Periodic Table


  Elements are arranged in order of atomic (proton) number, in groups and periods

  
• Elements in the Periodic Table

  • Elements with similar properties are in columns, known as groups
  • Elements with the same number of shells of electrons are arranged in rows called periods

  
• Electronic configuration


  Tells you how many electrons are in each shell around an element's nucleus
• • Electrons fill the shells closer to the nucleus before filling any further out
  • 1st shell holds 2 electrons, 2nd and 3rd hold 8
• Metals


  • Generally conductive (of electricity)
  • If an element is conductive and its oxide is basic, then the element is a metal
• Non-metals


  • Not conductive (excluding graphite)
  • If an element is not conductive and its oxide is acidic, then it's a non-metal
• Metals


  • Elements that react to form positive ions
  • Majority of elements are metals
  • Found to the left and towards the bottom of the periodic table
• Non-metals


  • Elements that do not form positive ions
  • Found towards the right and top of the periodic table
• The divide between metals and non-metals can be seen by the red line in the periodic table at the top
• Group number


  Gives the number of electrons in the outer shell
• Period number


  Gives the number of electron shells
• The number of electrons in the outer shell is responsible for the way different elements react
• Elements in the same group have the same number of electrons in the outer shell, so they undergo similar reactions and have similar chemical properties
• Noble gases (Group 0)

  • They have 8 electrons in their outer shell (except helium, which has 2)
  • They are unreactive and do not easily form molecules, because they have a stable arrangement of electrons