AQA Chemistry A-level 3.2.2 Group II - The Alkaline Earth Metals Detailed Notes PDF
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These detailed notes cover Group 2 (alkaline earth) metals in A-level chemistry, including their atomic radius, reactivity, ionization energy, melting points, reactions with water, and uses of their compounds. The notes also touch upon the solubility of their hydroxides and sulfates, extraction of titanium using magnesium, and flue gas removal using calcium oxide.
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AQA Chemistry A-level 3.2.2: Group II - The Alkaline Earth Metals Detailed Notes This work by PMT Education is licensed under https://bit.ly/pmt-cc https://bit.ly/pmt-edu-cc CC BY-NC-ND 4.0...
AQA Chemistry A-level 3.2.2: Group II - The Alkaline Earth Metals Detailed Notes This work by PMT Education is licensed under https://bit.ly/pmt-cc https://bit.ly/pmt-edu-cc CC BY-NC-ND 4.0 https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc 3.2.2.1 - Group II The Group II metals lose two electrons to form 2+ ions when they react in order to achieve a full outer shell. Atomic Radius The atomic radius of group II metals increases down the group due to additional electron shells. Reactivity Increased electron shielding down the group makes the outer electrons easier to lose. Therefore reactivity of the group II metals increases down the group. Ionisation Energy The first ionisation energy of group II metals decreases down the group due to a greater atomic radius and increased amounts of shielding. Melting Point The group II elements are metallic meaning the larger the ions within the metallic structure, the weaker the attractive forces as the attractive force has to act over a much greater distance. Therefore the melting points decrease down the group. Reactions with Water The group II 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 II metals are known as the alkali metals. Example: The magnesium is oxidised from OS (oxidation state) 0 to OS +2. (Oxidation is loss of e- ) Magnesium reacts very slowly in this way with liquid water, however the reaction can be much faster with steam as it provides the reaction with extra energy. When steam is used, the magnesium burns with a bright white flame to form hydrogen and magnesium oxide, a white powder. Example: https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Solubility of Hydroxides The solubility of group II hydroxides varies and means these compounds have different uses. Solubility increases down the group meaning magnesium hydroxide (Mg(OH)2) is the least soluble and barium hydroxide (Ba(OH)2) the most soluble. As a result, magnesium hydroxide is used in medicine as an antacid as it is alkaline and can neutralise acids. It is used in a similar way in agriculture to neutralise acidic soils. Solubility of Sulfates Group II sulfates decrease in solubility down the group meaning magnesium sulfate (MgSO4) is the most soluble and barium sulfate (BaSO4) is the least soluble. The insolubility of barium sulfate means it is very useful in medicine as barium meals. These are a form of medical tracer that allow internal tissues and organs to be imaged. 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. Example: Metal Extraction Magnesium is used in the extraction of titanium from titanium chloride via a displacement reaction. Example: Flue Gas Removal Calcium oxide reacts with sulfur dioxide to remove it from factory pollutants and prevent it from being released into the atmosphere. This forms calcium sulfite and water. Example: https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc
