• The reactivity of the group 1 metals?increases?as you go down the group
• When a group 1 element reacts its atoms only need to lose electron, as there is only 1 electron in the outer shell
  • When this happens, 1+ ions are formed

   

• The next shell down automatically becomes the outermost shell and since it is?already full,?a group 1 ion obtains?noble gas configuration
• As you go down group 1, the number of shells of electrons increases by 1
  • This means that the outermost electron gets?further?away from the nucleus, so there are?weaker?forces of attraction?between the outermost electron and the nucleus
  • Less energy?is required to overcome the force of attraction as it gets weaker, so the outer electron is lost?more easily
  • So, the alkali metals get more reactive as you descend the group

   

These electron shell diagrams of the first 3 alkali metals show that the group 1 metals have 1 electron in their outer shell