Group 2 Elements: Redox Reactions

The Group 2 ElementsThe elements in Group 2 all have hydroxides that are alkaline, which is reflected in the common name for this group: the alkaline earth metals.Physical PropertiesThe Group 2 elements have the following general properties: they have reasonably high melting and boiling points light metals with low densities form colourless compounds Electronic ConfigurationThe elements in Group 2 have their highest energy electrons in an s-sub shell. Together with Group 1 they form the s-block of the Periodic Table.Each Group 2 element has: two electrons more than the electronic configuration of a noble gas an outer shell containing two electrons Reactivity of Group 2 ElementsThe Group 2 elements are reactive metals and strong reducing agents.Group 2 elements are oxidised in reactions. Each atom loses two electrons from its outer s sub-shell to form a 2+ ion: M ---> M2+ +2e- Reactivity increases down the group, reflecting the increasing ease of losing electrons The decrease in ionisation energies down Group 2 is an important factor in this process. Reaction with OxygenThe Group 2 elements react vigorously with oxygen. this is a redox reaction the product is an ionic oxide with the general formula MO Calcium reacts with oxygen to form calcium oxide.2Ca + O2 ---> 2CaOBy applying oxidation numbers to this reaction, you can identify the oxidation and reduction processes. 0       0         +2 -20        0         +2 -2Calcium is oxidised and oxygen is reduced.Reaction with WaterThe Group 2 elements react with water to form hyroides with the general formula M(OH)2. Hydrogen gas is also formed. Ca + 2H2O ---> Ca(OH)2 + H20      +1            +2             0       +1                              0 only one H atom from each H2O has been reduced the other H atom does not change its oxidation number Mg reacts very slowly with water. As you move further down the group, each metal reacts more vigorously with water.

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