Group 2 Flashcards
What type of elements are group 2 ?
Alkali earth metals
What happens to atomic radius as you go down group 2.
Increases because more energy levels are being occupied.
What happens to electronegativity as you go down group 2.
Decereases because atomic radius and shielding increase therefore the positive attraction of the nucleus has less effect.
What happens to first ionisation energy as you go down group 2?
DecreSes because there is greater atomic radius and more shielding so the attraction between outer electron and nucleus decreases.
Why does magnesium alter from the melting point trend of group 2 and why ?
It is lower than expected because there is a difference in how atoms are packed in the metallic crystal.
Explain how each group 2 element reactions with water.
Be - does not react with water or steam.
Mg- reacts very slowly with water to produce magnesium hydroxide.
- reacts more vigorously and quickly with steam to produce magnesium oxide and hydrogen.
Ca- reacts steadily with water. Solution goes couldn’t because calcium is not very soluble and it effervescenth
Sr- reacts very quickly with water
Ba - reacts immediately with water
Write the reaction showing how magnesium reacts with water.
Mg(s) + 2H2O(l)- Mg(OH)2(s) + H2(g)
Write the reaction to show how magnesium reacts with steam.
Mg(s) + H2O(g) - MgO(s) + H2
What are the observations when calcium reacts with water and why ?
Solution goes cloudy because the solution is not very soluble.
Effervescent
Write the reaction to show calcium reacting with water.
Ca(s) + 2H2O(l) - Ca(OH)2(s) + H2(g)
Why are Sr and Ba kept in oil.
To prevent reactions with air.
Write the reaction to show Sr reacting with water.
Sr + 2H2O - Sr(OH)2 + H2
Write the reaction to show Ba reacting with water.
Ba + 2H2O - Ba(OH)2 + H2
What is the trend between the reactions of group 2 with water going down the group and why ?
They have more vigorous reactions going down the group because it is easier for the atoms to loose their pure electrons and therefore the metals are more easily oxidised.
They are better reducing agents down the group.
What happens to the solubility of group 2 hydroxides as you go down the group ?
Solubility increases.
Outline the solubility of each group 2 hydroxide.
Mg(OH)2 - insoluble so hydroxide formed reamsins on surface preventing further reaction.
Ca(OH)2 - slightly soluble
Sr(OH)2- soluble
Ba(OH)2- soluble.
Write the equation showing the reaction between magnesium chloride and sodium hydroxide.
MgCl2(aq) + 2NaOH(an) - Mg(OH)2(s) + 2NaCl
Write the ionic equation showing the reaction between magnesium chloride and sodium hydroxide.
Mg2+(at) +2OH- - Mg(OH)2(s)
Write the reaction showing how barium chloride reacts with sodium hydroxide.
BaCl2(aq) +2NaOH(aq) - Ba(OH)2(sa) + 2NaCl(aq)
Outline the solubility of the group 2 sulfates and their Trend.
Solubility decreases down the group
MgSO4 - soluble
CaSO4- slightly soluble
SrSO4- insoluble
BaSO4 - insoluble
Outline the reaction between magnesium nitrate and sulphuric acid.
Mg(NO3)2(aq) + H2SO4(am) - MgSO4(at) + 2HNO3(aq)
Write the reaction between barium nitrate and sulphuric acid.
Ba(NO3)2(aq) + H2SO4(aq) - BaSO4(s) + 2HNO3(aq)
Write the ionic reaction between barium nitrate and sulphuric acid.
Ba2+(aq) + SO42-(aq) - BaSO4(s)
What are the practical uses of magnesium hydroxide ?
Used in medicine to neutralise excess stomach acid which causes indigestion.
How is calcium hydroxide used on a practical level ?
Raises the Ph of acidic soils in agriculture - crops then grow more effectively.
How are sulphate ions tested for ?
With acidified BaCl2 or Ba(NO3)2 added and reacts with sulphate ions it will form a white precipitate.
Why is BaCl2 used to test for sulphate ions acidified.
To remove any carbonate ions which could give a false positive.
How do you test for carbonate ions.
Add hydrochloride acid. When carbonate ions react with hydrochloride acid they produce carbon dioxide. So bubble to has given off through limewater and if it turns cloudy, a carbonate ions was present.
What is the use of BaSO4 in medicine ?
It is used for X-rays.
A barium meal can be taken by mouth to outline the digestiv system in medical XRays and provides a contrast medium.
Why can BaSO4 be used in XRays despite being highly toxic.
It is so insoluble that it could not be absorbed by the digestive system.
How is Mg used in Titanium extraction. Use equations to answer.
The ore futile of impure titanium oxide is heated with chlorine and coke at a temperature of 1000 degrees.
TiO2 + 2Cl2 + 2C - TiCl4 + 2CO
TiCl4 can then be reduced using magnesium
TiCl4 + 2MG - Ti + 2MgCl2
For the elements Mg-Ba stars ehow the solubilities of the hydroxides and the solubilities if the sulphates change down group 7.
Solubility increase down the group for hydroxides.
Solubility increases down the group for sulphates.
Describe a test to show the presence of sulphate ions in an aqueous solutions.
Add acidified barium chloride.
Statue the trend in reactivity of the group 2 elements down the group with water.
Increases
Write an equation for the reaction of barium with water.
Ba + H2O - Ba(OH)2 +H2
Sulphates of the group 2 elements from Be to Ba have different solubiities. Give the formula of these sulphates and state one use that depends on the insolubility of this sulphate.
BaSO4
Used as a barium meal for XRays showing the digestive system
With the exception of beryllium chloride, group 2 chlorides are all classic ionic. Explain why beryllium chloride is different by considering how beryllium ion would interact with a chloride ion.
Be 2+ has a high charge density which polarises Cl- and causes the sharing of electrons.
