Group 2 Flashcards
Why are group 2 metals in the S block of the periodic table?
The outer electron is in the s subshell
Why does the 1st ionisation energy of group 2 metal decreases down the group?
Atomic radius increases
More shielding down group 2
Weaker attraction between nucleus and outer electrons
How does melting point change down group 2 (from calcium to barium)?
Decreases
Explain why calcium has a higher melting point than barium?
Barium has larger ions
Metallic bonds are weaker down the group and are more easily overcome
Weaker attraction between sea of delocalised electron and metal ions
So melting point decreases down group 2
How does reactivity change down group 2?
Increases down group 2
Group 2 metals react with water to form what two substances?
Metal hydroxide(aq) + H2(g)
Use of Mg(OH)2
Used as an indigestion remedy to neutralise stomach acid
Group 2 metals react with steam to form what two substances?
Metal oxides(s) + H2(g)
Group 2 oxides and hydroxides form what?
White solids
How does the solubility of group 2 metal hydroxide changes down the group?
Increases
How soluble is Mg(OH)2
Sparingly soluble
How soluble is Ba(OH)2
Completely dissolves
Group 2 metals react with H2SO4 to form what?
Metal sulphates
How does the solubility of group 2 sulphates change down the group?
Decreases
How soluble is BaSO4?
Insoluble
Use of barium sulphate?
Feeding the patient a barium metal
Absorbs X-rays
Digestive system can be seen
Why is barium sulphate safe to feed to patients even though it is highly toxic?
Insoluble so cannot dissolve and pass through cell membranes into body tissue
Test for sulphate ions (SO42-)
Add BaCl2
White precipitate
Why is BaCl2 used to test for sulphate ions?
The sulphate ions displace the chloride ions, forming the insoluble salt barium sulphate
Why is acidified BaCl2 solution to test for sulphate ions (2)
Acidified with hydrochloric acid
This is needed to react with carbonate impurities that are often found in salts which would form a white Barium carbonate precipitate and so give a false result
Write the equations for extraction of titanium using magnesium (2)
TiO2 + 2Cl2 + C —> TiCl4 + CO2
TiCl4 + 2Mg —> 2MgCl2 + Ti
What is Ca(OH)2 used for
Write an equation for this (2)
To neutralise soil
Ca(OH)2 + 2HCl –> 2H2O + CaCl2
What are flue gases (2)
Gases given out by power stations
Which are harmful to the environment
Two methods of desulphurisation (2)
CaO(s) + 2H2O(l) + SO2(g) + 0.5 O2 –> CaSO4.2H2O(s)
CaCO3(s) + 0.5 O2(g) + SO2(g) –> CaSO4(s) + CO2(g)
