Group 1 Elements

Group 1 Elements

1. common name = alkali metals (they form alkali solutions when they react with water)

2. Reactivity increases as you go down the group

3. Physical Properties

   • soft enough to be cut by a knife
   • have to be stored in oil to stop them reacting with the water in air
   • shiny when freshly cut, tarnish on exposure to air due to a layer of oxide forming
   • melting and boiling points decrease down the group
   • float on water - density goes up down the group
   • conduct heat and electricity

4. Experiment: reacting Gp 1 elements with water

   • Lithium: fizzed but didn't melt, reasonably vigorous but nothing too exciting
     • Lithium+Water⇒Lithium Hydroxide+Hydrogen
       • 2Li+2H₂O⇒2LiOH+H₂
   • Sodium: fizzed more than lithium, melted, more violent reaction than lithium, carried around by lots of Hydrogen, left a white trail
   • Potassium: produced a lila/purple flame (Hydrogen burns)
   • The pH of the solutions changed from neutral to alkali - the solution is a strong alkali