Ionic Bonds

• When atoms form ions, they try to fill up or empty their outer electron shell. In ionic bonding, a metal atom transfers electrons to a non-metal atom, allowing both of them (the metal and non-metal) to have a full outer electron shell.
• Group 1 metals

  • Group 1 metals always lose 1 electron to form positive ions with a charge of +1.
  • E.g. a sodium atom (Na), with the electronic structure (2,8,1), loses its outer electron when forming an ion to make Na+.

  
• Group 2 metals

  • Group 2 metals always lose 2 electrons to form doubly positive ions.
  • E.g. a magnesium atom (Mg), with the electronic structure (2,8,2), loses both its outer electrons when forming an ion to make Mg2+.

  
• Non-metals (groups 6 & 7)

  • Non-metal atoms always gain electrons to form (become) negative ions.
  • E.g. a fluorine atom (F), with the electronic structure (2,7), will gain an electron when forming an ion to make F-.

  
• Noble gases (Group 0)

  • Noble gases already have a full outer shell. Noble gases are unreactive and don't normally form ionic bonds with other elements.