S~Block Elements
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s-block ~ I II [I Li Be 3 4 d -bl ock Na Mg A..-- 11 12 I K Ca 19 20 Rb Sr 37 38 Cs Ba 55 56 Fr Ra 87 88 Periodic Table of the Elements o 2 I He II ill] III IV V VI VIII 4.0 3 4 5 6 7 8 9 10 Li Be B C N 0 F Ne 6.9 9.0 10.8 12.0 14.0 16.0 19.0 20.2 11 12 13 14 15 16 17 18 Na Mg Al Si P S CI Ar 23.0 24.3 27.0 28.1 31.0 32.1 35.5 39.9 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 3! 36 K Ca Sc Ti V Cr Mn Fe Co Ni eu Zn Ga Ge As Se BrlKr 39.1 40.1 45.0 47.9 50.9 52.0 54.9 55.9 58.9 58.7 63.5 65.4 69.7 72.6 74.9 79.0 79 83.8 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 S4 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 85.5 87.6 88.9 91.2 92.9 95.9 99.0 101.1 102.9 106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.91 ' 3 ' . 3 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Cs Ba La 4 Hf Ta W Re Os If Pt Au Hg Tl Pb Bi Po AtlRn 132.9 137.3 138.9 178.5 181.0 183.9 186.2 190.2 192.2 195.1 197.0 200.6 204.4 207.2 209.0 210.0 210.01222.0 87 88 89 Fr Ra Ac~ 223.0 226.0 227.0 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 140.1 140.9 144.2 (147) 150.4 152.0 157.3 158.9 162.5 164.9 167.3 168.9 173.0 175.0 90 91 92 93 94 95 96 97 98 99 100 101 102 103 "--- Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lw 232.0 231.0 238.1 (237) 239.1 (243) (241) (247) (251 ) (254) (253) (256) ( 254) (257) A value in brackets denotes the mass number of the most stable isotope. UNIT lJ s-Block Elements 1IIIIill[~llrlllll~lilr~11111 N27910 L.- E ~ Inner London Education Authority 1983 First published 1983 by John Murray (Publishers) Ltd 50 Albemarle Street London W1X 480 Reprinted 1984~ 1985~ 1987 All rights reserved. Unauthorised duplication contravenes applicable laws Printed and bound in Great Britain by Martin's of BerwicK British Library Cataloguing in Publication Data Independent Learning Project for Advanced Chemistry s-BlocK Elements. - (ILPAC; Unit 11) 1. Science I. Title II. Series 500 0161.2 ISBN 0 7195 4049 6 1/ CONTENTS PREFACE v ACKnowledgements vi Key to activity symbols and hazard symbols vii INTRODUCTION 1 Pre-Knowledge 2 PRE-TEST 3 THE s-BLOCK ELEMENTS 5 PHYSICAL PROPERTIES 5 Electronic configurations 5 Atomic and ionic radii 6 Ionization energies 7 Electronegativity B Melting points and boiling points 9 Hardness 10 CHEMICAL PROPERTIES 11 Reaction with water 11 Reaction with dilute acid 13 Reaction with oxygen 14 Experiment 1 - reaction between sodium peroxide and water 15 Reaction with nitrogen 19 General properties related to electron loss 20 Reaction with hydrogen 20 s-BLOCK COMPOUNDS 22 THE EFFECT OF HEAT ON SOME s-BLOCK COMPOUNDS 22 Experiment 2 - heating nitrates and carbonates 22 The hydrogencarbonates, sulphates and hydroxides 26 The hydrogencarbonates 27 The sulphates 27 The hydroxides 2B THE SOLUBILITY OF THE s-BLOCK COMPOUNDS IN WATER 29 Experiment 3 - the solubility of some salts of Group II elements 30 THE DIAGONAL RELATIONSHIP BETWEEN LITHIUM AND MAGNESIUM 33 END-OF-UNIT CHECKLIST 36 END-OF-UNIT TEST 37 APPENDIX 41 SOME INDUSTRIAL CHEMISTRY OF THE s-BLOCK ELEMENTS 41 The Downs process for the extraction of sodium 41 The extraction of magnesium from sea-water 42 The manufacture of sodium hydroxide 42 Some uses of s-blocK elements and compounds 44 ANSWERS TO EXERCISES 46 ii i PREFACE This volume is one of twenty Units produced by ILPAC, the Independent Learning Project for Advanced Chemistry, written for students preparing for the Advanced Level examinations of the G.C.E. The Project has been sponsored by the Inner London Education Authority and the materials have been extensively tested in London schools and colleges. In its present revised form, however, it is intended for a wider audience; the syllabuses of all the major Examination Boards have been taken into account and questions set by these boards have been included. Although ILPAC was initially conceived as a way of overcoming some of the difficulties presented by uneconomically small sixth forms, it has frequently been adopted because its approach to learning has certain advantages over more traditional teaching methods. Students assume a greater responsibility for their own learning and can work, to some extent, at their own pace, while teachers can devote more time to guiding individual students and to managing resources. By providing personal guidance, and detailed solutions to the many exercises, supported by the optional use of video-cassettes, the Project allows students to study A-level chemistry with less teacher-contact time than a conventional course demands. The extent to which this is possible must be determined locally; potentially hazardous practical work must, of course, be supervised. Nevertheless, flexibility in time-tabling makes ILPAC an attractive propo- sition in situations where classes are small or suitably-qualified teachers are scarce. In addition, ILPAC can provide at least a partial solution to other problems. Stude~ts with only limited access to laboratories, for ex~mple, those studying at ev~ning classes, can concentrate upon ILPAC practical work in the laboratory, in the confidence that related theory can be systematically studied elsewhere. Teachers of A-level chemistry who are inexperienced, or whose main discipline is another science, will find ILPAC very supportive. The materials can be used effectively where upper and lower sixth form classes are timetabled together. ILPAC can provide 'remedial' material for students in higher education. Schools operating sixth form consortia can benefit from the cohesion that ILPAC can provide in a fragmented situation. The project can be adapted for use in parts of the world where there is a severe shortage of qualified chemistry teachers. And so on. A more detailed introduction to ILPAC, with specific advice both to students and to teachers, is included in the first volume only. Details of the Project Team and Trial Schools appear inside the back cover. LONDON 1983 v ACKNOWLEDGEMENTS ThanKs are due to the following examination boards for permission to reproduce questions from past A-level papers: Oxford and Cambridge Schools Examination Board Teacher-marKed exercise, p17(1976) Oxford Delegacy of Local Examinations Teacher-marKed exercise, p35(19B1) End-of-Unit Test 6(1977) University of London Entrance and School Examinations Council Exercise 5 (N1974) Teacher-marKed exercises, p21(L19BO), p35(L197B) End-of-Unit Test 2(L1981), 4(L1979), 5(N197B), 7(L19B1) Welsh Joint Education Committee End-of-Unit Test 1(1979) Where answers to these questions are included, they are provided by ILPAC and not by the examination boards. Questions from papers of other examining boards appear in other Units. Photographs are included by permission as follows: Nuclear reactor, p9 - Popperfoto Cutting potassium metal, p10 - Tony Langham Potassium reacting with water, p12 - Tony Langham Stalagmites and Stalactites, p27 - Popperfoto X-ray photograph of stomach, p32 - Southend General Hospital Photographs of students - Tony Langham vi SYMBOLS USED IN ILPAC UNITS 0 ill Reading Revealing exercises Exercise Discussion ~ ® ~\;'"Test ~ Computer programme ~ Experiment o 'A' Level question I[ 11 Video programme 'A' Level part question 00 - [Q8 Film loop 'A' Level question Special paper ~ Model-making Worked example ~ [] Teacher-marked exercise INTERNATIONAL HAZARD SYMBOLS Radioactive [Xl Harmful I~I Toxic ! ~ I Flammable ~.f_~ Explosive ~ ':'4 Corrosive !~! Oxidising vii INTRO DUCTION In this Unit we deal with the elements and compounds of Groups I and II (the s-blocK). To remind you of the elements in these groups, we include their symbols and group names in the outline Periodic Table in Fig. 1 below. s-block p-block ~ II OJ III IV V VI VII 0 Li Be 3 4 d-block .I. K Ca 19 20 Rb Sr 37 38 Cs Ba 55 56 Fr Ra 87 88 0 - Fig.1. We deal with Groups I and II concurrently so that we can maKe comparisons between them, as well as consider the trends in properties within each group. Since this is a short Unit, and there is no obvious progression of difficulty in the subject matter, we have not divided it into two Levels. Consequently there is no Level One Test. In the first part of the Unit we deal with the physical and chemical proper- ties of the elements. (The distinction between physical and chemical properties is not rigid; we simply use the terms as convenient labels for organising information.) Then we consider the properties of some of the compounds of the s-blocK elements. In an appendix we consider briefly some of the industrial chemistry of these elements and their compounds.