Group 2 Elements Flashcards
Describe the reaction between group 2 elements and water
M + 2H2O –> M(OH)2 + H2
Describe the reaction between group 2 elements and oxygen
This is a redox reaction
2M + O2 –> 2MO
Describe and explain the trend in reactivity of the group 2 elements
As you go down the group, there are more electron shells, meaning the atomic radius increases. The atomic radius is increased further by electron shielding, where inner electron shells repel out shells. Elements with more electron shells have more electron shielding, meaning the outer electrons are pushed further from the nucleus. Because the electrons are further from the nucleus, the attraction between the outer electrons and the nucleus decreases, so the outer electrons are more easily lost. These elements form cations more easily, and are therefore more reactive
Group 2 metal hydroxide + 2HCl –>
Group 2 metal chloride + 2H2O
The hydroxide will dissolve
Group 2 metal oxide + 2HCl –>
Group 2 metal chloride + H2O
The solid will oxidise
Group 2 metal oxide + H2O –>
Group 2 metal hydroxide
The solution will be alkaline (typically PH of 10-12)
Group 2 hydroxide + aq –>
Group 2 oxide (2+) + 2OH(-)
Group 2 metal carbonate + heat –>
Group 2 metal oxide + CO2
This type of reaction is thermal decomposition
Name one use of calcium hydroxide
It is used by farmers and gardeners as ‘lime’ to neutralise acidic soils
Name one use of magnesium hydroxide
It is used in ‘milk of magnesia’ to relieve indigestion. It works by neutralising any excess acid in the stomach
Describe the trend in ease of decomposition of group 2 carbonates
They become more difficult to decompose down the group
Describe the trend in solubility of group 2 hydroxides
The solubility of hydroxides increases down the group so the resulting solution is more alkaline
