The Periodic Table

• Group 7 displacement:

  • More reactive Group 7 elements can take the place of less reactive ones in a compound.
  • This is called displacement. For example, fluorine displaces chlorine as it is more reactive: fluorine + potassium chloride ➞ potassium fluoride + chlorine
• Group 7 elements are called halogens
• Halogens are non-metals that exist as molecules made up of pairs of atoms
• Group 7 reactivity:

  • decreases going down:
  • atoms increase in size
  • weaker electrostatic attraction
  • more shells
• This is because they react with water to form an alkali ( a solution of their hydroxide)
• Group 1 elements are called alkali metals
• For example:

  • lithium + oxygen = lithium oxide
  • lithium + chlorine = lithium chloride
  • lithium + water = lithium hydroxide + hydrogen
• Noble gases have the following properties:

  • full outer shell with 8 electrons
  • are unreactive ( inert)
  • boiling points that increase down the group
• Group 0 elements are known as noble gases