AQA group 2, the alkaline earth metals
Allergy chemistry revision
Students should be able to:
-Explain the trends in atomic radius and first ionisation energy
-examine the melting point of the elements in terms of their structure
and bonding
-the reaction of the elements Mg-Ba with water
The use of magnesium int ht e extraction of titanium from TiCl 4
The relative solubility’s of the hydroxides of the elements Mg-Ba in
water.
Mg(OH)2 in medicine an of Ca(OH)2 in agriculture.
The use of CaO or CaCO3 to removes SO2 fro flue gasses
The relative solubilities of the sulphates if the elements Mg-Ba in water
BaSO4 is insoluble
The use of acidified BaCl2 solutions to test for sulphate ions.
The use of BaSO4 in medicine
Students should be able to explain why BaCl solution is used tot test
for sulphate ions and why it is acidified.
Atomic radius
Group 2 elements form +2 ions when they react.
Group 2 metals lose 2 electrons to from +2 ions. All group 2 metals have
electron configurations that end in s2. The atomic radius increases as you go
down the group 2.
Ionisation energy
1st ionisation energy deceases as we go down group 2
Extra shells added as you go down the group. There is more shielding as a result
hence weaker attraction between he nucleus and outer electrons. The outer
electrons are also further from the nucleus which weakens the attraction. Both of
these make it easier to remove the outer electrons and so less energy is needed
to remove the outer electrons, lower ionisation energy. Although there is an
increase in the number of protons in the number o protons as we go down the
group. However the shielding effect overrides an increase in positive charge.
Allergy chemistry revision
Students should be able to:
-Explain the trends in atomic radius and first ionisation energy
-examine the melting point of the elements in terms of their structure
and bonding
-the reaction of the elements Mg-Ba with water
The use of magnesium int ht e extraction of titanium from TiCl 4
The relative solubility’s of the hydroxides of the elements Mg-Ba in
water.
Mg(OH)2 in medicine an of Ca(OH)2 in agriculture.
The use of CaO or CaCO3 to removes SO2 fro flue gasses
The relative solubilities of the sulphates if the elements Mg-Ba in water
BaSO4 is insoluble
The use of acidified BaCl2 solutions to test for sulphate ions.
The use of BaSO4 in medicine
Students should be able to explain why BaCl solution is used tot test
for sulphate ions and why it is acidified.
Atomic radius
Group 2 elements form +2 ions when they react.
Group 2 metals lose 2 electrons to from +2 ions. All group 2 metals have
electron configurations that end in s2. The atomic radius increases as you go
down the group 2.
Ionisation energy
1st ionisation energy deceases as we go down group 2
Extra shells added as you go down the group. There is more shielding as a result
hence weaker attraction between he nucleus and outer electrons. The outer
electrons are also further from the nucleus which weakens the attraction. Both of
these make it easier to remove the outer electrons and so less energy is needed
to remove the outer electrons, lower ionisation energy. Although there is an
increase in the number of protons in the number o protons as we go down the
group. However the shielding effect overrides an increase in positive charge.
