3.2.2 Group 2, the alkaline earth metals Flashcards
(21 cards)
What is the general trend in Atomic Radius?
Increases as you go down
Extra electronic shell as you go down each period
Whatis the gerneral trend in First Ionisation Energy?
Decreases as you go down
Further distance between the nucleus and the outermost electron therfore less energy required to remove electrons
What is the general trend in Melting Point?
Overall Decrease as you go down
Metallic structure size increaes, therefore more electrons in the ‘Sea’ of delocalised electrons which are further away from the positive nucleus
What is the only group 2 element that deviates from the Melting point trend?
Magnesium which has the lowest temperature
What is the reaction between Calcium and water?
Ca(s) + 2H2O(l) –> Ca(OH)2(aq) + H2(g)
What is the oxidation state changes of the calcium in the reaction between it and water?
2+ -> 0
How does the reaction change going down the group?
Decreases as you go down
Due to smaller ionisation energy
What is the trend in solubility of Group 2 Hydroxides?
Increases as you go down the group
What is the use of Mg(OH)2?
In medicine
Used as for anticonstipation - Saline Laxitive
What is the use of Ca(OH)2?
In agriculture
Liminting agent to increase the soil pH
What is the reaction between a group 2 and a sulfate?
Ba2+(aq) + SO42-(aq) –> BaSO4 (aq)
What is the trend in solubility of Group 2 Sulfates?
Decrease as you go down the group
What is the use of BaSO4?
In medicine
Insoluble and can be seen through x-rays of soft tissues
What are the three main uses of Group 2 metals?
Extraction of titanium
Removal of SO2 from flue gas
Test for Barium Ions
Which Group 2 metal is used in the extraction of titanium?
Magnesium
How is the Group 2 metal used in the extraction of titanium?
Titanium oxide become Titanium Chloride.
TiCl4 is then purifided by being reduced into Mg in a furnace at 1000 degrees celcius
What is the equation for Mg and TiCl4
TiCl4 (g) + 2Mg (g) –> Ti (s) + 2MgCl2 (l)
Which Group 2 compound is used in the removal of SO2 from flue gas?
Calcium Oxide
Calcium Carbonate
How is the Group 2 compound used in the removal of SO2?
A slurry of CaO or CaCO3 is sprayed onto the flue gas and the SO2 reacts with it
What are the Flue gas equations?
CaO (s) + 2H2O (l) + SO2 (g) -> CaSO3 (s) + 2H2O (Calcium Oxide reaction)
CaCO3 (s) + 2H2O (l) + SO2 (g) -> CaSO3 (s) + 2H2O + CO2 (Calcium Carbonate reaction)
How do you use a group 2 compound to test from SO4- ions?
React BaCl2 with the solution
If SO4- are present the solution will form a white ppt called BaSO4
H2SO4 (aq) + BaCl2 (s) –> BaSO4 (s) + 2HCl (aq)
