periodicity

• Elements in the Periodic Table are arranged in order of increasing proton/atomic number
• Horizontal rows of elements in the Periodic Table are called periods
• Vertical columns of elements in the Periodic Table are called groups
• Metals are found left side of the Periodic Table
• Metalloids are found close to the zigzag line in dividing the elements in the Periodic Table.
• Metalloids are elements that have the properties of both metals and non-metals
• 
  

  As we go across a period, the elements:

  1. change from metals to non-metals
  2. change from positive ions to negative ions
  3. increase in the number of valence electrons
• Going down a group, the number of electron shells increases.
• what increases when going down a group

  1. metallic character
  2. proton number
  3. number of electron shells
  4. size of atom / atomic radius
• Elements in the same period have the same number of electron shells
• Elements in the same group have the same number of valence electrons
• Elements in the same group have similar

  chemical properties
• The noble gases are unreactive because they already have full outer shells (octet). And have stable a electronic configuration
• group (1 2 3 4 3 2 1 0) = valence electrons