CH9 Group 2 Flashcards
Equation for 1st ionisation energy of magnesium
Mg (g) –> Mg+ (g) + e-
What happens to the first ionisation energy going down group 2 - why
Decreases - number of filled electron shells increases so more shielding, bigger atomic radius - weaker force between outer electron and nucleus so less energy needed to remove it
How does reactivity with water change down group 2
Increases - outer electrons further from nucleus and more electron shielding so electrons are more easily lost
Barium and water reaction
Ba (s) + 2H2O (l) –> Ba(OH)2 (aq) + H2 (g)
Magnesium and steam reaction
Mg (s) + H2O (g) –> MgO (s) + H2 (g)
Trend in hydroxide solubility
Increases down group
Mg(OH)2 sparingly soluble
Ba(OH)2 creates strong alkaline solution
Trend in sulphate solubility
Decreases down group
MgSO4 is soluble
BaSO4 is insoluble
Trend in melting point down group 2 - why
Decreases - Sea of delocalised electrons is further from the positive charge of nucleus - weaker forces of attraction so less energy needed
Trend in atomic radius
Increases as there are more occupied electron shells down the group
Equations for the extraction of Titanium using magnesium
TiO2 + 2Cl2 + C –> TiCl4 + CO2
TiCl4 (l) + 2Mg (s) –> 2MgCl2 (s) + Ti (s)
What are flue gases
Gases produced by power stations which are harmful to the environment
How can CaO or CaCO3 be used to remove flue gases
CaCO3 (s) + SO2 (g) –> CaSO3 (s) + CO2 (g)
CaO (s) + SO2 (g) –> CaSO3 (s)
What is Ca(OH)2 used for
Used to neutralise soil
Ca(OH)2 (aq) + 2HCl (aq) –> 2H2O (l) + CaCl2 (aq)
What is Mg(OH)2 used for
Milk of magnesia - antacid to treat indigestion
What is a use of BaSO4
In barium meals to outline gut in X-rays
Ba2+ is toxic but is fine as barium sulphate as it is insoluble
