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Group 2 The alkaline Earth metals
These Elements all have 2 valence electrons in
their outer shell which are lost when they bond
ionically in order to form 2+ ions, giving them full
Trends In Reactivity
As you go down the group the ionisation energies
of the group 2 elements decreases due to the
increasing atomic radius and shielding
This causes the reactivity of group 2
metals to increase, as when they react
they lose electrons in order to form
cations, meaning that the easier it is to
lose electrons (i.e. the lower the first and
second ionisation energies) the more
reactive the element will be.
Reactions with Water and Oxygen
When group 2 elements react, they are
oxidised from an oxidation state of 0 >
+2 forming 2+ ions.
· Half equation:
Ca à Ca 2+ + 2e--
Reactions with water:
When group 2 elements react with water, they produce a metal hydroxide and
M + H2O à M(OH)2 + H2
Reactions with oxygen:
When group 2 elements react with oxygen they form solid white oxides.
2M + O2 à 2MO
Group 2 oxides and hydroxides
· Group 2 oxides and hydroxides are bases they form alkaline solutions in
· The oxides of the group 2 metals react readily with water to form metal
hydroxides which dissolve.
· The hydroxide ions OH make these solutions alkaline.
CaO + H2O à Ca 2+ + 2OH
· APART FROM MAGNESIUM OXIDE which is so insoluble that the ions do
· Oxides form stranger alkaline solutions as you move down the group.
Group 2 Carbonates
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The thermal stability of carbonates changes down the group.
· Thermal decomposition is when a substance breaks down when heated.
· The amount of heat needed to decompose a group 2 element increases
causing the thermal stability to increase down the group.
· Group 2 carbonates decompose to form the oxide and carbon dioxide.
MCO3 à MO + CO2
Uses of Group 2 Elements
Group 2 compounds are used to neutralise acidity.
Calcium hydroxide is used in agriculture to neutralise acidic soils.…read more