3.1.2
Group 2
Section 3.1.2 covers the s² outer shell of the Group 2 elements and their redox reactions with oxygen, water and dilute acids, the trend in reactivity explained by the first and second ionisation energies, the action of water on the oxides and the increasing alkalinity of the solutions, and the uses of Group 2 compounds as bases. The solubility and thermal stability pages are revision support that connects this section to 3.1.4.
Revision Notes
5 revision notes, in the order the specification teaches them.
Trends Down Groups 1 and 2
The trends down Group 2: atomic radius, ionisation energies, melting points and the increase in reactivity down the group.
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Reactions of the Group 1 and 2 Elements
The reactions of the Group 2 elements with oxygen, chlorine, water, steam and dilute acids, with equations, observations and redox analysis.
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Oxides, Hydroxides and Carbonates
Group 2 oxides, hydroxides and carbonates: reactions with water and acids, pH trend, and uses of Ca(OH)₂, Mg(OH)₂ and CaCO₃.
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Solubility Trends and the Sulfate Test
Group 2 solubility trends: hydroxides and sulfates, Mg(OH)₂ and BaSO₄, the acidified barium chloride test for sulfate ions and barium meals.
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Thermal Stability and Flame Colours
Thermal stability of Group 1 and 2 nitrates and carbonates, polarisation by the cation, the experiments, and flame colours explained by electron transitions.
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Group 2 Map
OCR A Level Chemistry A · 3.1.2 Group 2
The whole section on one A4 page: electron structure, oxygen and water, dilute acids, oxides with water, bases in use and reactivity explained.
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3.1.2
- b (i)
the relative reactivities of the Group 2 elements Mg–Ba shown by their redox reactions with oxygen
Revise - b (ii)
the relative reactivities of the Group 2 elements Mg–Ba shown by their redox reactions with water
Revise - b (iii)
the relative reactivities of the Group 2 elements Mg–Ba shown by their redox reactions with dilute acids
Revise - c
the trend in reactivity in terms of the first and second ionisation energies of Group 2 elements down the group (see also 3.1.1 c)
Revise - d iii
the trend of increasing alkalinity of the solutions resulting from the action of water on Group 2 oxides
Revise - e (i)
uses of Group 2 compounds as bases, including equations: Ca(OH)2 in agriculture to neutralise acid soils
Revise - e (ii) a
uses of Group 2 compounds as bases, including equations: Mg(OH)2 as an 'antacid' in treating indigestion
Revise - e (ii) b
uses of Group 2 compounds as bases, including equations: CaCO3 as an 'antacid' in treating indigestion
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