Group 1

• • The Group 1 elements are known as the alkali metals
  • They form alkaline solutions when they react with water
• • The alkali metals share similar characteristic chemical properties because they each have one electron in their outermost shell
  • Some of these properties are:
  • They are all soft metals which can easily be cut with a knife
  • They have relatively lowdensities and low melting points
  • They are very reactive (they only need to lose one electron to become highly stable)
• • The alkali metals are soft and easy to cut, getting softer as you move down the group
• • The first three alkali metals are less dense than water ( lithium sodium and potassium)
• • They all have relatively low melting points which decrease as you move down the group, due to decreasing attractive forces between outer electrons and positive ions
• • 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 down the group so the outer electron is lost more easily
  • So, the alkali metals get more reactive as you descend the group
• • Alkali metals react readily with oxygen and water vapour in air, so they are usually stored in oil to stop them from reacting
• • The reactions of the alkali metals with water get more vigorous( stronger) as you descend the group, as with the other reactions( oxygen and chlorine)
• Reaction of lithium and water

  lithium  + water   →   lithium hydroxide  +  hydrogen

  Observations:

  • Relatively slow reaction
  • Fizzing
  • Lithium moves on the surface of the water
• Reaction of potassium and water

  potassium  + water   →   potassium hydroxide  +  hydrogen 

  observations:

  • Reacts more vigorously than sodium 
  • Burns with a lilac flame 
  • Moves very rapidly on the surface 
  • Dissolves very quickly 
• Reaction of sodium and water

  potassium  + water   →   potassium hydroxide  +  hydrogen 

  • Reacts more vigorously than sodium 
  • Burns with a lilac flame 
  • Moves very rapidly on the surface 
  • Dissolves very quickly 
• • Rubidium, caesium and francium will react even more vigorously with air and water than the first three alkali metals
• • The alkali metals react with oxygen in the air forming metal oxides, which is why the alkali metals tarnish when exposed to the air
  • The metal oxide produced is a dull coating which covers the surface of the metal
• Reaction of lithium and oxygen 


  lithium + oxygen → lithium oxide 
• Reaction of sodium and oxygen 


  sodium + oxygen → sodium oxide 
• Reaction of Potassium and oxygen


  potassium  + oxygen →  potassium oxide 
• • All the group 1 metals react vigorously when heated with chlorine gas to form salts called metal chlorides
  • This reaction becomes more vigorous moving down the group, the same as with the reaction between the metals and water
• • All the group 1 metals react vigorously when heated with chlorine gas to form salts called metal chlorides
  • This reaction becomes more vigorous moving down the group, the same as with the reaction between the metals and water
• Reaction of lithium and chlorine 


  lithium  + chlorine →   lithium chloride
• Reaction of sodium and chlorine. 


  sodium  + chlorine →   sodium chloride
• Reaction of potassium and chlorine 


  potassium  + chlorine →   potassium chloride
• Lithium produces a solution of lithium hydroxide when reacted with water
• Sodium produces a solution of sodium hydroxide when reacted with water
• Potassium produces a solution of potassium hydroxide when reacted with water