Chemistry 111 Lab Periodic Properties Page J 1 PERIODIC PROPERTIES OF THE ELEMENTS T he purpose of this experiment is to explore the chemistry of a few of the elements both in the laboratory and by computer You will look for trends in the chemical and physical properties of the elements as a function of the position of the elements in a periodic group Adapted from General Chemistry Laboratory Chemistry Department University of WisconsinMadison GENERAL DIRECTIONS 1 Follow the experimental procedure detailed in the laboratory write up 2 Record your observations in the Data Section of this handout for the reactions observed In this experiment some reactions occur immediately some take longer some never occur The element being investigated is always the limiting reagent if it reacts all of it should be consumed Note any and all reactions that may occur Especially record similarities and differences between different elements within the same group and between elements of different groups From your observations try to determine the form and formula of the resulting products 3 From your observations complete the questions at the end of this writeup 4 Using the computer program The Chemistry Navigator which is available on the Macintosh computers in the Chemistry Physics Computer Center in Room 122 complete the attached Periodic Properties Computer Exercise EXPERIMENTAL PROCEDURE Use distilled or deionized water in all experiments calling for water Record all observations on the accompanying data sheets as you do the experiment Write chemical equations for all reactions observed if no reaction is observed write n r in the appropriate space Observation of Properties A The Group IA Elements Alkali Metals Lithium and Sodium 1 Using a clean dry watch glass get a small piece about 1 8 in diameter about 0 03 g of metallic lithium and sodium under kerosene from your instructor Handle these pieces with dry forceps or tongs Remove the excess kerosene from the metal by pressing the metal against a piece of paper towel After you are finished with the paper towel thoroughly wet the paper towel in the sink and then discard it in the waste bucket 2 Cut the piece of sodium metal with the end of a spatula and simultaneously observe what happens as the freshly cut surface is exposed to the atmosphere 3 Drop the small piece of sodium metal into 50 mL of distilled water in a 250 mL beaker simultaneously covering the beaker with a wire gauze Keep the beaker at arms length Test the resulting solution with litmus paper 4 Carry out the same reaction with lithium metal Record your observations 3 Li 6 941 11 Na 22 998 19 K 39 0983 37 Rb 85 4678 55 Cs 132 905 The Group 1A alkali metal elements Revised June 2005 Page J 2 Chemistry 111 Lab Periodic Properties B The Group 2A Elements Alkaline Earth Metals Magnesium and Calcium 4 Be 9 0122 12 Mg 24 305 20 Ca 40 078 38 Sr 87 62 56 Ba 137 327 Most of the Group 2A or alkaline earth metals 1 Grasp a small piece of magnesium ribbon with crucible tongs and while holding it at arm s length insert it in the burner flame Do not look directly into the flame Record your observations and write the balanced equation for the reaction 2 Repeat the test with a small piece of calcium Record the observations 3 Scratch a small piece of magnesium ribbon with a spatula Make up a test tube of 5 mL of water and a few drops of phenolphthalein indicator Place your magnesium in the test tube Record your results 4 Repeat this test with water and a small piece of calcium It may be necessary to break the calcium into small pieces Record the observations and note the difference in behavior of these elements toward water as compared to the metals of Group 1A Write equations for the reactions 5 Place 5 mL of 6 M HCl in each of two test tubes Carefully drop a piece of magnesium into one test tube and a piece of calcium into the other Place an inverted test tube over one of the test tubes to collect a sample of the gas being evolved Immediately put the inverted test tube over an open flame Record the observation C The Group 3A Elements Aluminum 5 B 10 81 6 C 12 011 13 14 Al Si 26 9815 28 0855 31 Ga 69 723 32 Ge 72 61 50 9 In Sn 114 82 118 710 4 81 82 Tl Pb 204 383 207 2 Groups 3A and 4A of the periodic table 1 Grasp a small piece of aluminum wire with crucible tongs and while holding it at arm s length insert it in the burner flames Record the observations 2 Place about 0 25 g of granular aluminum in a test tube containing water and another sample of aluminum in a 150 mL beaker containing 5 mL of 6 M HCl Record the observations Write a balanced equation for any reaction you may observe D The Group 4A Elements Carbon Place about 0 25 g of powdered carbon in a test tube containing water and another sample of carbon in a test tube containing 5 mL of 6 M HCl Tap the bottom of each tube gently with a finger Wait 5 minutes then tap each tube again Record your observations E The Group 7A Elements the Halogens Chlorine Bromine and Iodine Here you will place a small quantity of aqueous solutions of each of the halogens Cl2 Br2 and I2 in a small test tube On adding hexane an organic liquid that does not mix with water you will see two layers in the test tube After observing the color of the halogen dissolved in hexane the next step is to mix a halogen with the salt of another halogen and then add hexane In some cases the halogen will oxidize the halide ion in a reaction such as Cl2 aq 2 Br aq 2 Cl aq Br2 aq When this particular reaction occurs the bromine released in the reaction dis Revised June 2005 Chemistry 111 Lab Periodic Properties Page J 3 solves in the hexane layer and you observe the characteristic color of bromine in the hexane Part E 1 Color of Halogens in Hexane The purpose of this part of the experiment is to discover the color that each halogen Cl2 Br2 and I2 has in the organic solvent hexane 1 Add chlorine water 9 Place about 2 mL of chlorine water chlorine dissolved in water bromine Hexane layer in which halogen dissolves with characteristic color Water layer Testing for a halogen When you shake or swirl the test tube you will find that the halogen will preferentially dissolve in the hexane and not the water Therefore the hexane layer will take on a color characteristic of the dissolved halogen Because hexane is less dense than water the hexane layer will float on top of the water F 18 9984 17 Cl 35 4527 35 Br 79 904 53 I 126 9045 85 At 210 The Group 7A elements or the halogens water …