• There are over 100 chemical elements which have been isolated and identified
• Elements are arranged on the periodic table in order of?increasing atomic number
  • Each element has one proton?more?than the element preceding it
  • This is done so that elements end up in columns with other elements which have similar properties

   

• The table is arranged in vertical columns called?groups?and in rows called?periods
  • Period:?These are the horizontal rows that show the number of shells of electrons an atom has and are numbered from 1 - 7
  • E.g. elements in period 2 have two electron shells, elements in period 3 have three electron shells

   

• Group:?These are the vertical columns that show how many outer electrons each atom has and are numbered from 1 – 7, with a final group called group 0 (instead of group 8)
  • E.g. group 4 elements have atoms with 4 electrons in the outermost shell, group 6 elements have atoms with 6 electrons in the outermost shell and so on

   

The Periodic Table of the Elements