Group 2 Flashcards
What is the trend in atomic radius down the group?
Increase in atomic radius
Why does atomic radius increase down the group
Due to a greater number of electron shells
What is the trend in first ionisation energy as we go down the group?
Decreases
Why does first ionisation energy decrease as we go down the group
No. of shells increases
Increased shielding
Decreased attraction between nucleus and outer e-
What is the trend in melting point down group 2?
Generally decreases
Explain the trend in melting point
Generally decreases
Due to
Number of delocalised electrons and charge stays the same
Whilst size of ion increases
Charge density decreases
Weaker attraction between metal cations and delocalised electrons giving a weaker metallic bond
What is the exception to the trend in melting point of G2
Mg
Melting point is lower than expected because it has a different crystal structure
What is the general equation for group two elements reacting with water
X + 2H2O —> X(OH)2 + H2
State the trend in reactivity with water of group two elements
Reactions become more vigorous
What is the equation for the reaction between magnesium and steam
Mg + H2O –> MgO + H2
What is observed when magnesium reacts with steam
Mg burns with a bright white light, producing a white powder MgO
What is the equation for the extraction of Ti from TiCl4 using Mg
TiCl4 + 2Mg —-> Ti + 2MgCl2
TiCl4 + 2Mg —-> Ti + 2MgCl2
What is the reducing agent in this equation and what is the oxidising agent
Mg: Reducing agent
TiCl4: Oxidising agent
What are the required conditions for the extraction of Ti from TiCl4 using Mg
500-1000 degrees C
Inert argon atmosphere
State the two required flue gas desulphurisation equations
CaO + SO2 —> CaSO3
CaCO3 + SO2 —> CaSO3 + CO2
What type of reaction is a flue gas desulphurisation reaction
Acid base / neutralisation reaction
What type of gas is sulphur dioxide (SO2)
Acidic
What are the two bases in both of the flue gas desulphurisation reactions
CaO
CaCO3
Name the metal oxide in one of the flue gas desulphurisation reactions
CaO
Name the metal carbonate in one of the flue gas desulphurisation reactions
CaCO3
How is SO2 formed through the combustion of petrol
Crude oil naturally contains sulfur
Combustion of petrol can lead to the formation of SO2
Why is SO2 bad
Contributes to acid rain
What are the two benefits of flue gas desulfurisation
Environmental: SO2 is removed from power stations (Less contribution to acid rain)
Economical: CaCO3 is converted to CaSO3 which is used to make plasterboards
What is the general formula for group two hydroxides
X(OH)2
What is the trend in solubility of group two hydroxides
Solubility increases down the group
What is the general formula for group two sulphates
XSO4
What is the trend in solubility for group two sulphates
Solubility decreases down the group
Describe the solubility of barium sulphate
Insoluble
What is the use for Mg(OH)2
Antacid; neutralises excess stomach acid
What is the use for Ca(OH)2
Agriculture; Increases the pH of soil to make it more alkaline
What is the use for BaSO4
Barium meal, turns up opaque in x rays
What is the test for sulphate ions
- Add HCl to remove CO32- ions (2H+ + CO32- —> CO2 + H2O )
- Add BaCl2
(BaCl2 —> Ba2+ + 2Cl-)
(Ba2+ + SO42- —> BaSO4)
BaSO4 forms white precipitate
White precipitate = positive test
What is the test for Ba2+
- Add H2SO4
(H2SO4 —> 2H+ + SO42-)
(H+ removes any carbonate ions) - Ba2+ + SO42- –>BaSO4
BaSO4 gives a white precipitate
White precipitate = positive test
Write an equation for the reaction of TiCl4 with water
TiCl4 + 2H2O —> TiO2 +4HCl
What is a solute
Something which can be dissolved in a solvent
