Group 2 Flashcards
State and explain the trend in atomic radius down group 2
Radius increases as the number of filled electron shells increases down the group.
State and explain the trend in the 1st ionisation energy down group 2
1st ionisation energy decreases down the group.
Electron shielding and radius increases down the group, therefore electrostatic attraction between nucleus and outer electron shell decreases meaning it is easier to remove the outer electron
State and explain the trend in mpt down group 2
Mpt decreases down the group (Mg as an exception). This is because as size of ion increases the distance between nucleus and delocalised electron field increases meaning a weaker electrostatic attraction requiring less energy to overcome
Write a general equation for the reaction of Ca, Sr or Ba with water
M(s) + 2H20(l) —> M(OH)2(s) + H2(g)
How is the reaction of Mg with water different than that of Ca, Sr or Ba with water
Mg will only react immediately with steam not liquid water ( H2O (g) not H2O (l) )
Describe the reaction of Mg with steam and write an equation
A bright white flame is observed, producing a white solid Mg0
Mg(s) + H20 (g) —> MgO (s) + H2(g)
Explain why very clean Mg will have a slow reaction with water
Mg contains an oxide layer that prevents it reacting with water .
Cleaning the Mg removes the oxide layer
Explain how Mg is used to extract titanium from its ore (rutile)
TiO2 + 2Cl2 + 2C —> TiCl4 + 2CO
TiCl + 2Mg —> Ti + 2MgCl2
- Mg is used as the reducing agent rather than C, because carbon reduction also produces titanium carbide (TiC) which is brittle
Write a general simple ionic equation for the reaction of aqueous group 2 ions with sodium hydroxide solution
M^2+ (aq) + 2OH- (aq) —> M(OH)2
state of product depends on solubility of hydroxide
State the trend of solubility of hydroxides of group 2
Increases down the group Mg(OH)2 is insoluble (s), Ba(OH)2 is soluble (aq)
Give a use of Mg(OH)2 in medicine
Milk of magnesia, neutralises excess stomach acid (antacid tablets)
Give a use of Ca(OH)2 in agriculture
Used to neutralise acidic soils for growing crops
How are CaO and CaCO3 used to remove acidic flue gases (SO2) from coal burning emissions?
