Group 2, the alkaline earth metals Flashcards
How does atomic radius change down group 2
It increases as each element has an extra level of electrons filled
How does ionisation energy change down group 2
Decrease down the group as outer shell electrons get further away. There is more shielding
How does melting and boiling point change down group 2
Decreases as the sea of delocalised electrons are further away from the positive nuclei
What happens when group 2 elements are put in water (redox)
They are oxidised as they want to lose 2 electrons
How does reactivity with water change down group 2
Metals get more reactive down the group
What is the general equation for a group 2 reaction with water
M + 2H2O —> M(OH)2 + H2
What is the equation for magnesium reacting with steam? Is it fast or slow?
Mg + H2O —> MgO + H2
Fast
What is Mg(OH)2 used for
Neutralises excess stomach acid which causes heart burn
What is the equation for magnesiums reaction with water? Is it fast or slow
Mg + 2H2O —> Mg(OH)2 + H2
Very slow
What is Ca(OH)2 used for
Used to treat acidic soil
How is magnesium used in the extraction of titanium TiCl4
TiCl4 + 2Mg —> 2MgCl2 + Ti
What is the trend in hydroxide solubility down group 2
Hydroxides become more soluble down the group
How can Mg(OH)2’s solubility be decribed
Sparingly soluble
What can CaO and CaCO3 be used for
Removing SO2 from flue gasses
What is the trend in sulphate solubility down group 2
They become less soluble down group 2
How soluble is Barium Sulphate (BaSO4)
It is insoluble
What is Acidified BaCl2 used for?
What is a positive result?
The test for sulphate ions
A white precipitate is a positive result
What is BaSO4 used for
Barium sulphate can be used in X-rays as it is opaque to x-rays meaning that the rays won’t pass through it
It is very insoluble so won’t be absorbed
Why is BaCl2 used to test for sulphate ions and why must it be acidified
The sulfate ions displace the chloride ions, forming the insoluble salt barium sulfate
The acid reacts with any carbonate ions that could give a false positive
Compare the pH of Mg(OH)2 and Ca(OH)2
Ca(OH)2 is higher as more soluble
