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Group 2 (Alkaline Earth Metals) - Coggle Diagram
Group 2 (Alkaline Earth Metals)
Physical Properties
Going down the group....
Atoms get larger
Melting point decreases
Density increases
Reactions
Form ionic compunds; ions have charge +2
Act as reducing agents
Reactivity increases going down the group
Grp 2 metal+ dil. HCl ---> metal chloride + hydrogen
Mg + dil sulfuric acid ---> magnesium sulfate + hydrogen; but for all other meta;s, the reaction is quickly stopped by the formation of an insoluble sulfate layer on the surface of the metals. Group 2 sulfates get less soluble going down the group.
Reaction with oxygen: the metals form white solid oxides (basic in nature)
basic oxide + dilute acid ---> salt + water
Flame Tests
Calcium: Red
Strontium: Scarlet/ Red
Barium: apple-green
Reactions with Water
weakly alkaline solution (hydroxide)+ hydrogen
Calcium oxide + water ---> calcium hydroxide (s); calcium hydroxide dissolves in water to give Ca 2+(aq) + 2OH- (aq)
In general, the reaction dissolving the group 2 metal oxides in water is: o2- (s) + H2O(l) ---> 2OH- (aq)
The solutions formed from the reactions get MORE ALKALINE GOING DOWN THE GROUP
Solubility of group 2 hydroxides increases going down the group
IMP: Reaction of Barium hydroxide with dilute sulfuric acid. The salt, barium sulfate forms as a precipitate, unlike the soluble barium chloride.
Reactions of group 2 carbonates
Thermal decomposition: break down to meral oxide and carbon dioxide gas. The temperature at which the decomposition happens increases down the group. Nirtrates also undergo this reaction, giving a metal oxide, NO2 (observed as brown gas) and oxygen gas
All carbonates are insoluble in water
React with dilute acid forming a salt and water and giving off CO2 gas
With dil. H2SO4
Sulfates of Ca, St and Ba tend to form as an insoluble sulfate layer on their solid carbonates
MgSO4 is soluble in water and stays in aqueous solution
With dil. HCL
All group 2 metals form SOULBLE chloride salts, water, and CO2 gas