Why are the Group 1 Elements so Reactive ?
The first three elements in Group 1 are Lithium, Sodium and Potassium and the three pictures below show the arrangement of electrons in their atoms. They have all got one electron in the outside shell even though they all have a different number of electrons in total. If you compare these pictures with the periodic table, above, you might notice that the elements have more electrons as you go down the the group.
