Group 2 Flashcards
State and explain, the trend of atomic radius in group 2.
Atomic radius increases down the group. this because it has more shells of electrons.
State and explain, the trend of melting point down group 2
Melting point decreases down the group. Metallic bonding weakens as ionic radius increases. This is because distance between the cation and the sea of electrons increases the electrostatic attraction decreases.
State and explain, the trend of 1st ionisation energy down group 2.
the valiant electron are held more weakly down the group because of the increased shielding and distance between it and the nucleus reducing the ionization energy.
State the trend of reactivity of group 2 metals.
increases down the group.
Shows a reactions of group 2 metals and oxygen.
2Mg + O2 -> 2MgO
show reactions of Mg species with HCl
Mg + 2HCl -> MgCl2 + H2
MgO + 2HCl -> MgCl2 + H2O
show reactions of Mg with water.
Mg(s) + H2O (g)-> MgO(s) + H2(g)
rapid reaction
Mg + 2H2O -> Mg(OH)2 + H2
slow reaction
Show reactions of group 2 metals with cold water.
Ca + 2H2O(l) -> Ca(OH)2(aq)+H2(g)
Sr + 2H2O -> Sr(OH)2(aq) + H2
Ba + 2H2O (l) -> Ba(OH)2 (aq) + H2(g)
if the hydroxide salt is soluble then the solution becomes alkaline.
State observations of reactions of group 2 metals with water.
Fizzing,
metal dissolving,
solution heats up,
calcium produces white precipitant.
explain how titan is extracted.
TiO2(s) + 2Cl2 + 2C -> TiCl4 (l)+ 2CO at 900oC
the TiCl4 is purified with fractional distillation.
TiCl4 + 2Mg -> Ti + 2MgCl2
Ti is extracted in an argon atmosphere at 500oC
State reasons why Ti is expensive.
Mg is expensive and is used to extract it.
This is a batch process.
The process is expensive due to argon.
high temperatures in both steps.
State the trend of solubility of group 2 hydroxide.
solubility increases down the group.
State the observation of insoluble group 2 hydroxides.
White precipitant.
explain the solubility of Mg(OH)2
Mg(OH)2 is classed as insoluble in water.
the equation for the simplest formation of Mg(OH)2 is Mg2+ (aq) + 2OH- (aq) -> Mg(OH)2(s). although a suspension of Mg(OH)2 is pH9 so some OH- ions are present so some Mg(OH)2 does dissociates.
explain how Mg(OH)2 is used in medicine.
Mg(OH)2 + 2HCl -> MgCl2 + 2H2O
Mg(OH)2 in a suspension called milk of magnesia neutralizes excess acid in the stomach and to treats constipation.
it is safe to uses as its so weak of an alkaline. it is preferable to use over CaCO3 as it will not produce CO2 gass
