2.2 Group 2 Flashcards
what happens to the atomic radius down group 2
- atomic radius increases
- shielding increases, making atom bigger
what happens to the melting point down group 2?
- melting points decrease
- metallic bonding weakens as size of atom increases
- distance between positive ions and delocalised electrons increases, so strength of electrostatic forces weakens
what happens to the 1st ionisation energy down group 2 ?
- ionisation energy decreases
- outermost electrons are successively further from the nucleus.
what happens to the reactivity of group 2 metals down the group?
- reactivity increases
give an equation and observation for magnesium reacting with steam
- Mg(s) + H20(g) > MgO(s) + H2(g)
- Mg burns with a bright white flame
- MgO appears as white powder
give an equation for reaction of magnesium with water
Mg + 2H20 > Mg(OH)2 + H2
- much slower reaction, no flame
what are observations for group 2 metals reacting with cold water ?
- fizzing ( more vigorous down group )
- metal dissolving ( faster down group )
- solution heating up ( more down group )
- with calcium a white precipitate appearing ( less forms down group )
why is titanium a very useful metal?
- abundant
- low density
- corrosion resistant
what are the steps in extracting titanium
- TiO2(s) is comverted to TiCl4(l) at 900C
- TiCl4 is purified by fractional distillation in an argon atmosphere
- Ti is extracted by Mg in an argon atmosphere
explain why titanium cannot be extracted with carbon and via electrolysis
- titanium carbide ( TiC ) is formed rather than titanium
- cannot be extracted by electrolysis because it has to be very pure
give equations for extraction of titanium from magnesium
TiO2 + 2Cl2 +2C > TiCl4 + 2CO
TiCl4 + 2Mg > Ti + 2MgCl2
why is titanium expensive?
- expensive cost of the magnesium
- batch process, making it expensive
- process expensive due to the argon
- high temperatures required in both steps
give equation for removal of waste gases from furnaces
- SO2 + CaO > CaSO3
what happens to the solubility of hydroxides down group 2
they become more soluble
- all group 2 hydroxides appear as white precipitates, when not soluble
why is magnesium hydroxide used in medicine ?
- it is used to neutralise excess acid in the stomach
- it is safe to use because it is so weakly alkaline
why is barium meal safe to use ?
- barium sulfates low solubility means it is not absorbed into the blood
how can i test for the presence of a sulfate ion?
- BaCl2 solution acidified with HCl is used as a reagent
- if BaCl2 is added to a solution that contains sulfate ions a WHITE PRECIPITATE of barium sulfate forms
Ba^2+(aq) + SO4^2-(aq) > BaSO4
why is the hydrochloric acid needed
to react with carbonate impurities that are often found in salts which would form a white barium carbonate precipitate aka a false result
how can we tell if a carbonate was present?
fizzing due to CO2 would be observed
