group 2

• what ions do group 2 form

  2+ ions as they lose 2 electrons when they react to achieve a full outer shell
• what happens to the atomic radius of group 2 metals as you go down the group?

  increases as more electron shells
• What happens to the reactivity as you go down group 2?

  Increases as increased electron shielding down the group makes the outer electrons easier to lose.
• what happens to the ionisation energy as you go down group ?

  decreases as greater atomic radius and increased amount of shielding.
• what is the melting point trend in group 2 as you go down the group

  decrease as you go down the group
• what bonds are present in group 2

  metallic
• REACTIONS WITH WATER

  the group 2 metals react with water in a redox reaction to produce a metal hydroxide and hydrogen. The metal hydroxide form as an alkaline solution, hence why the group 2 metals are known as the alkali metals

  eg: Mg + 2H20—————->Mg(OH)2 + H2

  this reaction is very slow

  to make this reaction faster use steam as it provides the reaction with extra energy.

  When steam is used the reaction burns with a bright white flame to form hydrogen and magnesium oxide (white powder)

  Mg + H2O —————-> MgO + H2
• SOLUBILITY OF HYDROXIDES

  solubility increases as you go down the group hence magnesium hydroxide (Mg(OH)2 is the least soluble and barium hydroxide (Ba(SO4) is the least soluble
• SOLUBILITY OF SULFATES

  sulfates decreases in solubility down the group, so magnesium sulfate (MgSO4) is the most soluble and barium sulfate (BaSO4) is least soluble.

  the insolubility of barium sulfate means it is very useful in medicine as barium metals. Barium sulfate is toxic if it enters the bloodstream, however because it is insoluble, it cannot be absorbed into the blood. Therefore it is safe to use in this way.

  barium chloride is used as a test for sulfate ions as it reacts to form barium sulfate which forms as a white precipitate when sulfate ions are present.
• what happens to the first ionisation energy as you go down a group?

  decreases. This is because the increased distance and shielding from the nucleus outweighs the increase in nucleus nuclear charge
• group 2 are all alkaline earth metals
• alkaline earth metals are solid at room temperature
• what happens to the strength of metallic bonds as you go down group 2 and why does this happen?

  the strength of the metallic bonds decreases as you go down group 2, this is because the size of cation increases as you go down the group
• as you go down group 2 the melting point decreases
• what is extraction

  separating a metal from its ore
• what is magnesium used for?

  useful for the extraction of titanium
• Titanium is extracted from its ore in 2 stages:

  first, titanium dioxide is heated with carbon and chlorine, to form titanium chloride.

  Then, the titanium is reduced by magnesium, which forms magnesium chloride.

  Heating titanium dioxide with carbon( the usual method of extracting metals) produces a carbide which is too brittle to be used as an engineering material.
• burning fossil fuels like coal produces sulphur dioxide ( acid rain)
• When sulfur dioxide(SO2) reaches the atmosphere/ sky it reacts with oxygen to form SO3

  2SO2(g) + O2 (g) ----> 2SO3(g)
• sulfur trioxide reacts with water in rain clouds to form

  2SO2 (g) + O2(g) ---> 2SO3 (g) sulphuric acid this causes acid rain
• burning fossil fuels gives off sulfur dioxide, which cause acid rain. This can be prevented by spraying a slurry of calcium oxide or calcium carbonate over the sulfur dioxide gas, and collecting the calcium sulphate that forms
• Many metals do not exist in the earth’s crust as pure metals but as metal ores. The pure metal must be separated from its impurities. This is known as 

  extraction.For iron, this can be done by heating it with 

  carbon. However, this method is not suitable for titanium, because TiCTiC forms, which is weak, making it a poor engineering material.
• Ca (s) + 2H2O (l) ----> Ca(OH)2 (aq) + H2 (g)
• When Group 2 elements reacts with water, they form hydroxides. The speed of this reaction increases down the group. Beryllium does not react at all with water at room temp
• equation for reaction of magnesium and steam is:

  Mg (s) + H2O (g) ---> MgO (s) + H2 (g)
• The equation for the reaction between Magnesium and water at room temp is :

  Mg (s) + 2H2O ---> Mg(OH)2(aq) + H2(g)