group 1 - alkali metals

• they all have the same number of electrons in the outer shell therefore they have the same chemical properties
• alkali metals

  • are soft
  • have relatively low melting points
  • their reactivity increases down the periodic table
• How does lithium, sodium and potassium react in water ?

  lithium

  • floats on the water
  • fizzes
  • gives off hydrogen

  sodium

  • turns into a ball
  • fizzes quickly
  • gas produced

  potassium

  • lilac flame
  • lots of heat given off
• the reactivity increases down the group, lithium is the least reactive and francium is the most reactive
• Why does the reactivity increase down the group ?

  • each element in group 1 has one electron in the outer shell
  • when they undergo a chemical reaction they loose the electron, to form an ion with a positive charge
  • as the number of shells increases down the group it means that the distance from the electron and nucleus gets larger
  • meaning its easier to loose the electron