Paper 1 - The Alkali Metals

Question 1

How do the similarities in the reactions of Lithium, Sodium and Potassium with water provide evidence for their recognition as a family of elements?

Answer 1

• They all react vigorously
• They all produce a metal hydroxide solution which is alkaline - The Alkali Metals
• They all produce hydrogen gas

Question 2

How do the differences between the reactions of Lithium, Sodium and Potassium with air and water provide evidence for the trend in reactivity in Group 1?

Answer 2

• The lower down in group 1, the more reactive the metal
• This can be shown by the rate of reaction with water
• Lithium takes longer than sodium or potassium to react, so it is the least reactive
• Potassium takes the shortest time to react of the 3 elements so it is the most reactive
• The reactivity trend can also be seen in the reaction between an alkali metal and oxygen. Potassium reacts to form its oxide quicker than sodium and lithium when left in air

Question 3

Use your knowledge of trends in Group 1 to predict the properties of other alkali metals

Answer 3

• The further down in group 1, the more reactive the metal
• So it is predictable that Rubidium/Caesium/Francium will react more vigorously with water than potassium