group 1

• group 1 metals are alkali metals
• alkali metals are soft, have low density and low melting points
• alkali metals are more reactive as you go down the group because

  • The atomic radius increases down the group (the atoms get larger).
  • The force of attraction between the nucleus and outer electron decreases.
  • The electron is lost more easily (requires less energy to remove) from atoms lower down the group.
• melting points and boiling points decrease down the group as the atomic radius increases and the number of electrons increases
• Lithium


  Fizzes, forms a ball and slowly melts on the water surface
• Sodium


  Fizzes and moves quickly on the water surface
• Potassium


  Fizzes and moves quickly on the water surface, forms a ball and ignites with a purple flame
• As you go down Group 1

  The metals get more reactive
• Trend in reactivity in Group 1

  • Due to the atoms having one electron on the outer shell, and this electron gets further away from the nucleus as you go down the group
• The reactions of lithium, sodium and potassium with water can be used to show the trend in reactivity in Group 1