Group 2 (Alkaline Earth Metals)
No description yet. This curated deck is ready for daily study.
Card preview (18)
State and explain the trend in atomic radius down group 2
• increases • number of filled electron shells increases down the group
State and explain the trend in 1 st ionisation energy down group 2
• decreases down the group • Electron shielding and radius increases • Electrostatic attraction between nucleus and outer electron is weaker • easier/less energy to remove the outer electron
State and explain the trend in melting point down group 2
• Melting point decreases down the group (with exception of Mg which is lower than expected). • Size of ion increases the distance between nucleus and delocalised electron field • Weaker electrostatic attraction requiring less energy to overcome
Write a general equation for the reaction of Ca, Sr or Ba with water
M(s) + 2H2O(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 with steam not liquid water
Describe the reaction of Mg with steam and write an equation
A bright white flame is observed, producing a white solid MgO Mg(s) + H2O(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
TiO2 + 2Cl2 + 2C –> TiCl4 + 2CO TiCl4 + 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 simplest ionic equation for the reaction of aqueous group 2 ions with sodium hydroxide solution
M2+ (aq) + 2OH - (aq) –> M(OH)2 state of product depends on solubility of hydroxide
State the trend in 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?
Flue gases bubbled through a slurry of CaO or CaCO 3 . Produces a precipitate CaO + SO 2 –> CaSO3 CaCO3 + SO2 –> CaSO3 + CO2
Write the simplest ionic equation for the reaction of acidified barium chloride with sulfate ions or sulfuric acid and give an observation
Ba2+ (aq) + SO4 2- (aq) –> BaSO 4 (s) White precipitate formed
State the trend in solubility of the group 2 sulfates
Decrease in solubility down the group
Explain why barium chloride solution used to test for sulfate ions must be acidified
Prevents the formation of a white ppt of BaCO3 This is formed when atmospheric CO 2 dissolves in the solution
Give a use for barium sulfate in medicine and explain why it is suitable for this purpose
Barium meal. It is dense and absorbs X-rays Insoluble and therefore non-toxic
Why is the 2nd ionisation energy for magnesium is more endothermic than the 1st?
• removal of an electron from a Mg+ ion rather than a Mg atom • stronger electrostatic attraction due to greater effective nuclear charge