Inorganic: group 2 Flashcards
Explain the trend in atomic radius In group 2
Increases as number of shields increases down the group so shielding increases and weaker nuclear attraction between outer pair of electrons and nucleus
Explain the trend in first ionisation energy
Decreases down the group as number of shields increases so weaker nuclear attraction between outer pair of electrons and nucleus so easier to lose electrons
Explain the trend in melting point in group 2
Decreases as size of ions increases, so atomic radius increases so weaker nuclear attraction between outer pair of electrons and nucleus
Which group 2 element is an anomaly in melting point trend
Mg
How does Mg react with water? (Liquid)
Slow reaction with few bubbles
Mg(s) + H2O(l) -> Mg(OH)2(aq) + H2(g)
How does Mg react with steam?
Vigorously, with fizzing
Mg(s) + H2O(g) -> MgO(s) +H2(g)
How does calcium react with water
Moderately , fizzing
Ca(s) +H2O(l) -> Ca(OH)2(aq) + H2(g)
How does strontium react with water?
Vigorously, fizzing
Sr(s)+ H2O -> Sr(OH)2(aq) + H2(g)
How does barium react with water?
Vigorously, fizzing
Ba(s) + H2O -> Ba(OH)2(aq) + H2
Explain the trend in solubility in hydroxides
(HIdINg) increases down the group. Mg(OH)2 sparingly soluble
Explain the trend in solubility in sulfates
Decreases down the group , BaSO4 and SrSO4 insoluble
How do you test for sulfate ions?
- Add HCl acid to unknown sample to get rid of carbonate ions
- Add BaCl2 to sample and if sulfate ions are present, white ppt forms
How is magnesium used in titanium extraction?
Heated in a stream with chlorine and carbon
TiO2+ 2C + 2Cl2 (coke) -> TiCl4 + CO2
Reduction
TiCl4(l) +2Mg(s) -> 2MgCl2 + Ti
What is the use of magnesium hydroxide?
Neutralise excess stomach acid (indigestion)
What is the use of calcium hydroxide?
Raise PH of soils that are too acidic
