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Download Group2: Trends Chemical and Physical Properties 1) a) A group 2
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Group2: Trends Chemical and Physical Properties 1) a) A group 2 metal, X, fizzes when added to water. When a solution of sodium sulphate is added to a solution of XCl2, a white precipitate is formed. Identify X and write equations for reactions occurring. Identity of X ………………....................................................................................................................................... Reaction with water ………..................................................................................................................................... Reaction of XCl2 with sodium sulphate …............................................................................................................... (3) b) A group 2 metal, Y, has no visible reaction when added to water. When a solution of potassium hydroxide is added to a solution the nitrate of X, a white precipitate is formed. Identify Y and write equations for reactions occurring. Identity of Y ………………...................................................................................................................................... Reaction of nitrate of X with potassium hydroxide…............................................................................................. (2) c) State the trend in atomic radius down Group II from Mg to Ba and give a reason for this trend. Trend .................................................................................................................................................................... Reason ................................................................................................................................................................. (2) d) State and explain the trend in melting points of the elements down Group II from Mg to Ba. Trend .................................................................................................................................................................... Reason ................................................................................................................................................................. (3) e) State and explain the trend in ionisation energy of the elements down Group II from Mg to Ba. Trend ................................................................................................................................................................... Reason ............................................................................................................................................................... 2) (4) Radium is the element below barium is Group 2. a) State whether or not each of the following is soluble in water. i) radium hydroxide …………………………………………………………………………………………..………….. ii) radium sulphate ……………………………………..……………………………………………………..………….. (2) b) i) Is the atomic radius of radium more or less than that of barium? ………………………………………..………… ii) Explain your reasoning. ……………………………………………………………………………………..………….. (2) c) i) Is the first ionisation energy of radium more or less than that of barium? ………………………………..………. ii) Explain your reasoning. …………………………………………………………………………………………..…….. (4) d) i) Is the melting point of radium more or less than that of barium? ………………………………………..………… ii) Explain your reasoning. ………………………………………………………………………………………..……….. (3) State the Trends in the3 graphs 0.2 atomic radius (nm) Atomic radius General Trend………………………………………… 0.15 0.1 0.05 0 Be Mg Ca Sr Ba Mg Ca Sr Ba 1st ionisation energy 1st ionisation energy General Trend………………………………….. 900 800 700 600 500 400 300 200 100 0 Be Melting points 1600 General Trend……………………………………….. melting point (K) 1400 1200 1000 800 600 400 200 0 ANSWERS a) X = Ba (or Sr) Ba + 2 H2O Ba(OH)2 + H2 (or with Sr) 2+ 2- Ba + SO4 BaSO4 / BaCl2 + Na2SO4 BaSO4 + 2 NaCl (or with Sr) b) Y = Mg 2+ - Mg + 2 OH Mg(OH)2 / Mg(NO3)2 + 2 KOH Mg(OH)2 + 2 KNO3 c) atomic radius increases more shells of electrons d) melting points decrease weaker metallic bonding metal ions (atoms) are larger e) lower ionisation energy atomic radius greater more shielding weaker attraction between outer shell electrons and nucleus 2) a) i) radium hydroxide = soluble ii) radium sulfate = insoluble b) i) more ii) more shells of electons c) i) less ii) atomic radius greater more shielding Be Mg Ca Sr Ba weaker attraction between outer shell electrons and nucleus d) i) lower ii) weaker metallic bonding metal ions (atoms) are larger Graph Trends Atomic radius atomic radius gets bigger down the group more shells of electrons 1st ionisation energy atomic radius gets bigger down the group more shielding down the group Melting points lower melting points down the group as weaker metallic bonding as the ions get so large the sea of electrons cannot hold the metal together as well weaker metallic bonding as atoms (ions) get bigger change in trend after Mg due to change in way atoms (ions) pack together (pack together in a closer arrangement)
