Periodic Table: Basics (Edexcel IGCSE Chemistry: Double Science)

• 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

The Periodic Table of the Elements