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School of Physical Sciences

Department of Chemistry

General Chemistry CHM 172 2014 STUDY GUIDE

2014 CHM 172 STUDY GUIDE

Contents How to use the Study Guide ...................................................................................................................... 3 ORGANISATIONAL COMPONENT ............................................................................................................. 4

Credits and contact hours ...................................................................................................................... 4 Course coordinator, lecturers and laboratory manager ................................................................... 4 Course Website ...................................................................................................................................... 5 Study Material ...................................................................................................................................... 5 Calculator, Model Set, Laboratory coat and safety glasses ................................................................... 6 Practical Sessions: ................................................................................................................................ 6

Laboratory sessions / Tutorials .......................................................................................................... 6 Exemption from practical session activities (repeater students) ...................................................... 6 Laboratory Book ................................................................................................................................. 6 Preparation for Practical Laboratory sessions ................................................................................... 7 Dress Code in the Laboratory ............................................................................................................. 7

OWL and QUIZZES .................................................................................................................................. 7 Video Lectures ........................................................................................................................................ 9 Rules of Assessment and Exam Admission ..................................................................................... 9 Absenteeism ........................................................................................................................................... 9

STUDY COMPONENT ...............................................................................................................................10 Syllabus .................................................................................................................................................10 Critical Learning Outcomes ..................................................................................................................12 Outcomes of this Course ......................................................................................................................13 Study Themes .......................................................................................................................................15

ADDITIONAL STUDY MATERIAL ..............................................................................................................19 NOMENCLATURE ................................................................................................................................19 NAMES OF THE ELEMENTS ...................................................................................................................21 NAMES OF IONS (alphabetical English names) ....................................................................................22 NAMES OF SOME COMMON COMPOUNDS .........................................................................................23 LEWIS STRUCTURES ..............................................................................................................................24 BALANCING REDOX REACTIONS ..........................................................................................................26

CALENDAR ................................................................................................................................................28 INFORMATION PAGE ................................................................................................................................29

The Periodic Table of the Elements .....................................................................................................29 Electronegativity values of the elements according to the Pauling scale ............................................29 Equations ..............................................................................................................................................29 Constants .............................................................................................................................................29 Conversion Factors ...............................................................................................................................29

2014 CHM 172 2 / 29 © University of Pretoria


How to use the Study Guide This Study Guide comprises of an organizational component and a study component. The organizational component

The organizational component explains all the administrative and organizational arrangements regarding the presentation and evaluation of the semester course. You must closely follow the instructions given in this section.

The study component

Your learning activities should occur within the framework of the study component, which is divided as follows:

• Semester course: The semester course CHM172 affords sixteen credits.

• Syllabus themes: The semester course comprises nine syllabus themes. These nine themes represent a broad division of the learning contents of the semester course.

• Study units: Some of the themes are divided into study units

• Learning objectives: A number of learning objectives are supplied for each study unit. These learning objectives are described at the end of each chapter in the prescribed textbook.

• Practice exercises: You will find good questions at the end of each chapter in the textbook. The answers to the uneven-numbered problems are available at the back of the textbook. First attempt these questions, ensuring that you are confident of your ability to do the even-numbered questions, even though you may not have their answers. You will not be successful without completing a good number of these problems. It is important to do the problems with the higher numbers. Suggested exercises from the textbook and accompanying CD are listed in the syllabus on page 10.

Class attendance is compulsory. The detail of the study units will be discussed during all contact sessions and important announcements are made. The lecturer gives an oversight of the themes and you will need to complete the themes by studying from your textbook in order to be successful in this course.

Recommended study hours: An absolute minimum of 1 hour for each chemistry lecture hour, most students need 2 hours. This excludes practicals and preparation for tests and examinations.



ORGANISATIONAL COMPONENT

Credits and contact hours 16 Credits = 4 Lectures per week and 1 × 3 hour practical/assignment/model-building/tutorial session (=7 hours contact) per week. There are two compulsory semester tests written during the Engineering test weeks. To earn 16 credits all these activities must be completed in the semester.

Course coordinator, lecturers and laboratory manager Course Coordinator English Lecturer Quarter 3 Mrs. B Castleman Office: NW1, Room 3-46 Telephone: 012-420-2043 Email: [email protected]

Afrikaans Lecturer Mrs. AC Botha Office: NW1, Room 2-19.1 Dial 4322 at the entrance Telephone: 012-420-4322 Email: [email protected]

English Lecturer Quarter 4 Mr. NJ De Beer Office: Chemistry Building, Room 2-31 Telephone: 012-420-4783 Email: [email protected]

Course Administrator Mrs. D Dry Office: Chemistry Building, Room 1-39 08h00 – 12h30 Telephone: 012-420-5156 Email: [email protected]

Tutorial & Practical Coordinator Mrs. A Swart Office: Chemistry Building, Room 2-32.3 Telephone: 012-420-3539 Email: [email protected]

Laboratory Manager Mrs. SP Lubuma Office: Chemistry Building, Room 3-22.1 Telephone: 012-420-6388 Email: [email protected]

If you find it difficult to get hold of your lecturer, it is a good idea to make an appointment directly after a lecture or you may also send an email to the lecturer. All administrative matters are handled by the course coordinator or by the administrative manager. The normal grievance sequence is:

Head of First Years Head of Department Prof. WJ Schoeman Prof. ER Rohwer Chemistry Building, Room 1-35 Natural Sciences Building, Room 3-11 Tel: 012-420-2759 Tel: 012-420-2512 email: [email protected] email: [email protected]

Lecturer Head of First Years

Head of Department


mailto:[email protected]








2014 CHM 172 STUDY GUIDE Course Website All information for this course, like announcements, notices, information, documents, marks, memoranda, etc. are available on the CHM 172 course clickUP page. It is every student's duty to visit the web page regularly and look for updates and new information.

Study Material Each student must have the following prescribed textbook. This book is essential to this course since all course material is based on this book.

Title: Chemistry and Chemical Reactivity Authors: JC Kotz, PM Treichel and JR Townsend Edition: Eighth (2012) Publisher: Thomson Brooks Cole ISBN-13: 978-1-111-42702-3

This textbook is bundled with a supporting CD, included in the price. Please ensure you get the CD with the book. Recommended but not essential book: Student Solution Manual for Kotz, Treichel and Townsend. Other very interesting material is available on the official website of the publisher. Students should visit this site to download and print the relevant material. You are, however, strongly encouraged to consult additional sources. The following text books are recommended as useful sources for additional study, and are available in the Merensky Library (Reserved Study Collection):

• Chemistry the Central Science, TL Brown, H LeMay and BE Bursten. • General Chemistry with Qualitative Analysis by KW Whitten, KD Gailey / ML Peck

and RE Davis, Saunders College Publishing, third ed., 1991; sixth ed., 2000. • Chemistry. The Molecular Science. by J Olmsted and GM Williams, McGraw& Hill

second ed., 1997. The scientific journals, Chemical and Engineering News, Chemistry in Britain, New Scientist, Nature, Scientific American and Journal of Chemical Education, are also available in the library (level 5), and offer many interesting articles.

For a better understanding of the chemistry of learning and the chemistry of memory formation in the brain, read the following: Spark, The Revolutionary New Science of Exercise and the Brain, by John J. Ratey. The book also explains the chemistry of physical exercise on the brain and why exercise is so important for intellectual development (and not too much TV and computers!). The book is available as an audio book on audible.com in MP3 or MP4 format – you can listen while taking a walk.


2014 CHM 172 STUDY GUIDE Calculator, Model Set, Laboratory coat and safety glasses Students purchase their own calculators and laboratory coats. Any type of scientific calculator is allowed, preferably one that can solve equations. Coats can be purchased from the campus shop or from Wizebooks. Coats must have long sleeves and hang to the knees (or just above the knees). Long pants (preferably cheap jeans) and closed shoes must be worn during all laboratory sessions. It is also advisable to bring your own dishcloth. Students who are not appropriately dressed will be asked to leave the laboratory. A molecular model kit and safety glasses will be issued by the Department. Every student must be in possession of his/her own items during practicals, tests and examinations. These items may under no circumstances be exchanged during tests or exams. If these items are lost /stolen, the replacement costs are for the student’s own private account.

Practical Sessions: Laboratory sessions / Tutorials It is a precondition that every student must attend and complete one 3 hours of Practical session - consisting of laboratory work or tutorials - per week as scheduled on the timetable. You will be excluded from examinations without completing these activities successfully. Tutorial tests, assignments and laboratory sessions will be evaluated. Experiments are done in the laboratories while tutorials are held in the lecture venue indicated in the timetable, unless announced otherwise.

Every student will be assigned to a practical group (day of practical and laboratory workstation). Students with academic reasons for changing sessions must please contact the Administrator for first-years (see p.4)

Exemption from practical session activities (repeater students)

Repeater students may repeat all the practical session activities or apply for exemption if your mark for this component was 60% or higher during the previous attempt. In the latter case, the semester mark will be calculated as the average of the two semester test marks plus the OWL marks. No marks from the previous attempt will be transferred. (You must complete a form to confirm your exemption application - this is available on the course clickUP page).

Laboratory Book Each student should have a laboratory book which is used for each practical laboratory session of this course: 1. The laboratory book should be an A4 soft-cover exercise book (72 pages). 2. It is used for each practical for preparation before a practical, and note-taking during a

practical. 3. It is also used by the student for reference later in the semester for preparation for practical

tests. 4. All preparation in this book must be in the handwriting of the student, and no printed

material from the webpage or photocopied documents may be pasted into this book. 5. When a student enters the laboratory, tutors will check the laboratory book of each student

for the required preparation. No student will be allowed into the laboratory without proof of the necessary preparation in the student’s own laboratory book, in his/her own handwriting.

6. The book should form a portfolio of all the practicals done by a student in this course. 7. At the end of the semester these books will be submitted and will become the property of

the Department of Chemistry. The books of students with borderline marks in the final examination can be used for re-evaluation.


2014 CHM 172 STUDY GUIDE Preparation for Practical Laboratory sessions A student should bring the following items along to the laboratory for each practical session: 1. A white laboratory coat (obtainable from the campus clothing shop); 2. A pair of safety glasses; 3. A box of matches; 4. A kitchen dish cloth; 5. Your laboratory book. 6. A non-permanent marker pen to mark glassware. It is essential for each student to do the necessary preparation prior to each scheduled session. The Department of Chemistry views the preparation of practicals in a very serious light, and no student will be allowed to enter the laboratory without thorough preparation of that particular practical. The preparation for each practical consists of the following steps: 1 Look on the CHM 172 timetable which practical is scheduled on a particular date; 2 Download and print out the material of that practical from the course website; 3 Carefully read through the material, consult the references and note the objectives; 4 Plan how you would execute the experimental procedure in the laboratory; 5 In your laboratory book:

5.1 Note the heading and aims of the experiment. 5.2 Make a list of all the reactants and their chemical formulas. Also write all the necessary

chemical equations of the reactions in the practical. 5.3 Make a flow diagram of the experimental procedure in your laboratory book. 5.4 Add detail to this diagram so that you will know exactly what to do in the laboratory,

without consulting the printed material from the website. (The printed material of the website is not allowed in the laboratory. You should rely solely on your preparation in your laboratory book.)

5.5 Note carefully what to look out for during the experiment. (You should write notes of all your observations during the practical in your laboratory book.)

5.6 Do not merely copy the experimental procedure and other instructions from the ClickUP document into your laboratory book. Instead: summarise the procedure, add your own notes and abbreviations so that it can be used to carry out the experiment.

6 This preparation should be done before you arrive at the laboratory. 7 Make sure that you bring along all the above mentioned items to the laboratory

Dress Code in the Laboratory The following rules apply for clothing in the laboratory: 1. A long white laboratory coat with long sleeves. 2. A pair of safety glasses. 3. A pair of long pants which covers the legs down to the ankles. 4. Closed shoes – no sandals or bare feet. 5. Long hair should be tied at the back. Note that these rules are for your safety. Students who do not comply with these rules will not be allowed into the laboratory and will forfeit the marks of that practical.

OWL and QUIZZES In this course a huge emphasis is placed on the independent self-work of students. It is expected of students to read the textbook, make their own notes and summaries and to do homework exercises on a continuous basis.

To aid students to achieve this goal, computer-based work sessions are prescribed (known as OWL, from Online Web Learning). This homework is done online and marks are assigned automatically. These marks are taken into consideration in the calculation of semester marks.


2014 CHM 172 STUDY GUIDE The closing dates of all OWL sessions are indicated on the accompanying OWL timetable. However, please note that each session is open and available for a couple of weeks before the closing date. Thus, students should not wait for the closing date to start and attempt the exercises of a particular session. If an OWL session is not completed and submitted before the closing date, all marks for that session are forfeited and such a session cannot be made up. In general two or more sessions are prescribed per week, of which all are compulsory.

The OWL sessions are not available on clickUP, but on the webpage of Cengage Learning. Please see the procedure elsewhere on this website how to register and to log onto this webpage.

NOTES on OWL exercises:

1. Most of the assignments are already available for you to do. But they have different due dates after which you cannot do them anymore.

2. You can do them in any order, at any time. 3. When an OWL exercise has expired, you can still view the content and practise, but

you will receive no further credit for it. 4. The time for each assignment is unlimited, but you must (in most cases) submit one

correct answer in the same session for a credit. 5. You can attempt an assignment an unlimited number of times, until you get the credit

for it. However, while the type of question will always be the same, the numerical values and compounds will differ.

6. Learn from the feedback with each question. This is the big advantage of the OWL system.

7. Recommendation: Write down the questions and answers. Also make notes of the simulations. These can be valuable study notes.

8. Use the numerical values from the OWL tables (like Avogadro’s number) and the Periodic Table (like molar masses). Do not use values from other sources.

9. Many assignments consist of two similar questions. Both must be attempted, of which one must be answered correctly for the credit.

10. Reserve at least 30 minutes at the computer for you to complete an assignment. However, some assignments are shorted and others can take longer.

11. Revise the particular section of the work in your notes and in the textbook before you attempt an assignment.

12. When you do an assignment you should have your calculator, textbook and stationary ready.

13. Numerical answers can be entered either in decimal or scientific notation. Again: click “Scientific Notation” in the table at the top of a question to learn how to enter scientific notation in OWL if needed.

14. Do not be in a hurry – some sections of OWL load slowly, especially the simulations. 15. All dates are displayed in American format, e.g. month/day/year. 16. Flash Player 9.0 (or later) must be installed and working on your browser to view the

animations. (Note: The Google Chrome browser already includes this.) 17. Again: all the assignments are available from the start. Do not wait for their due dates.

They can be done any time before the due dates, in any order. 18. Optional OWL exercises will be made available for enrichment. They do not have due

dates and will not count towards your semester mark. We strongly advise that you also complete these exercises to check your understanding.

Computer-based assessment activities (“Quizzes”) will open on your clickUP-page under “Assessment”. Complete these in the prescribed time.


2014 CHM 172 STUDY GUIDE Video Lectures The Lewis molecular structures of many compounds, with the experimental data, are available on the course clickUP page. Work through all these examples. (Follow the “Video Lectures” link on the CHM 172 clickUP page under “Additional Study material”).

Rules of Assessment and Exam Admission Two official and compulsory tests must be taken during the official test weeks. Tutorial/assignment tests will also be taken on regular intervals, on dates which will be announced beforehand.

The semester mark reflects your achievements in the semester tests, the class/tutorial tests, assignments and laboratory experiments. These marks will appear in “My Grades” on clickUP.

You will be evaluated on all the activities of the semester. Make sure to have your student card with you during all assessment activities.

A semester mark of 40% minimum, will give you admission to the examination.

NOTE: This applies ONLY if this mark is supported with satisfactory completion of all experiments / assignments / model building / tutorial sessions etc. You will receive an examination exclusion even if you have a semester mark of >40% , if all the activities and assignments have not been completed.

The semester mark is calculated as follows:

35% Semester Test 1 35% Semester Test 2 30% Combined experiment / tutorial / assignment / class test / OWL mark

For repeater students exempted from the practical session activities, the semester mark calculation is as follows:

45% Semester Test 1 45% Semester Test 2 10% OWL assignments

The final mark which determines whether a candidate will pass, fail, or qualify for a supplementary examination will be calculated as the arithmetical average of the semester mark and the exam mark. You need to obtain a subminimum of 40% in the examination to pass, irrespective of your semester mark. (See Faculty regulations)

Final Mark: (Semester Mark/50) + (Exam Mark/50) =100.

Absenteeism Absence from any formal activities included in the course (class tests, semester tests, tutorial tests, examinations, supplementary examinations, practical classes), must be supported by a medical certificate submitted to the Administrative Manager (see p4) within 3 working days after the activity has taken place. These certificates will be accepted only on condition that the certificate clearly states that the student was both ill and medically unfit to attend the specific activity on that particular day. Medical certificates that state: “I was told that ......(student) was ill on......”, will not be accepted. The certificate must also display the student number. The medical doctor must be registered at the Medical Board.

Supplementary tests and examinations will be given after authorized and confirmed absence. These tests could be taken orally, depending on the decision of the lecturer and course coordinator. It is the responsibility of the student to contact the course coordinator and make arrangements to catch up. In the case of a long illness the lecturer or course coordinator must be contacted by the parents of the student.



STUDY COMPONENT Refer to the CHM 172 clickUP-page for class notes and additional study material

Syllabus

Syllabus Theme Study Unit

Chapters Kotz & Treichel

8th Ed

& Suggested Exercises

# Lectures

(approx.)

1. Measurement Matter, Measurement and The Tools of Quantitative Chemistry

Chapter 1 and Appendices A & C

2 In-chapter 1 examples: 1.4 – 1.7 Tools of Quantitative Chemistry: Sections 1-6 End-of-Chapter 1 exercises: 8, 16, 29-30 Tools of Quantitative Chemistry: 23-26, 48-54 CD-ROM Chapter 1 Goals and Homework: 1, 3-6

2. Atomic Model, Compounds & Periodicity of Elements

2.1 Elements in the Periodic Table, Atomic Structure & Mass.

Chapter 2.1 – 2.8

4

In-chapter examples: 2.1- 2.7 End-of-Chapter 2 exercises: 5-8, 17-22, 27-29, 49-54, 57-60, 76, 97, 99 CD-ROM Chapter 2 Goals and Homework: 1-4 CD-ROM Chapter 3 Goals and Homework: 1-4

2.2 Nomenclature of compounds

2.3 Electron structure, Quantum Numbers and Orbitals

Chapter 6

In-chapter examples: 6.1-6.4 End-of-Chapter 6 exercises: 5-12, 14, 17, 21, 25-26, 33-36, 41-42, 57-60, 68 CD-ROM Chapter 7 Goals and Homework: 1–5

2.4 Electron Configurations and Periodicity

Chapter 7

3 In-chapter examples: 7.1-7.5 End-of-Chapter exercises: 6-10, 11, 14-16, 18, 21, 29-31, 40-43, 51, 59, 63. CD-ROM Chapter 8 Goals and Homework: 1-4

3. Bonding & Molecular Geometry

Molecular Structure, Bonding, Properties of Compounds

Chapter 8 and Lewis Structures on the clickUP page + Study Guide

7 DO NOT FOLLOW TEXT-BOOK METHOD WHEN DOING EXAMPLES End-of-Chapter exercises: 5-16, 18-19, 25, 33-37, 42, 44, 51, 75, 78 CD-ROM Chapter 9 Goals & Homework: 2c, 3, 5, 6

SEMESTER TEST 1

4. Compounds and formula stoichiometry

Mole concept; Mass percentage composition and empirical formula determination of compounds. Combustion analyses.

Chapters 2.9-2.11 & 4.4

3

In-chapter examples: 2.10 – 2.12 In-chapter examples: 4.3 – 4.5 End-of-Chapter 2 exercises: 81, 91-92, 118-119,140, 142 End-of-Chapter 4 exercises: 32 - 35 CD-ROM Chapter 3 Goals and Homework: 5 CD-ROM Chapter 4 Goals and Homework: 5



Syllabus Theme Study Unit

Chapters Kotz & Treichel

8th Ed

& Suggested Exercises

# Lectures

(approx.)

5. Chemical reaction equations

5.1 Types of Chemical reactions.

Chapter 3

4

In-chapter examples: 3.1-3.10 End-of-Chapter exercises: 5-6, 12, 20, 28, 38-40, 46, 48, 56, 57 CD-ROM Chapter 4 Goals and Homework: 1-4 (all) CD-ROM Chapter 5 Goals and Homework: 1-4 (all)

5.2 Balancing redox reactions in aqueous medium

Chapter 20.1 and Study guide

2 In-chapter examples: 20.1 End-of-Chapter exercises: 4, 6, 50 CD-ROM Chapter 20 Goals and Homework: 1

6. Stoichiometry Reaction Stoichiometry

Chapter 4

9

In-chapter examples: 4.1 to 4.2 & 4.6 – 4.13 End-of-Chapter exercises: 4, 6, 8, 10, 14-18, 21-22, 24-26, 28, 34-35, 44, 49-52, 55-57, 63-64, 71-72, 90, 98, 109, 116, 132. CD-ROM Chapter 4 Goals and Homework: 1–4 (all) CD-ROM Chapter 5 Goals and Homework: 5

SEMESTER TEST 2

7. Thermochemistry Energy and Reactions

Chapter 5

3

In-chapter examples: 5.1 to 5.9 End-of-Chapter 5 exercises: 15, 23, 27, 33, 38, 41, 43, 51, 55, 70, 73, 75, 81, 85, 98, 103 CD-ROM Chapter 6 Goals and Homework: 1a-f, 2a, 3a, 4a-c, 4e

8. Equilibrium & Thermodynamics

Equilibrium, Entropy and Free Energy

Chapters 16.1, 16.2; 17.4 p765; 18.4 p828-830, 19

5

In-chapter examples: 16.1 to 16.2 End-of-Chapter exercises: 1 – 6 In-chapter examples: 19.1 to 19.7 End-of-Chapter exercises: 5, 10, 15, 18, 21, 24, 26, 29, 37, 42, 43, 48, 53, 62, 63, 67 CD-ROM Chapter 19 Goals and Homework: 1a-d, 2a-b, 3a-c, 4a

9. Electrochemistry Electrochemical cells, electrolysis and thermodynamic relationships.

Chapter 20

5 In-chapter examples: 20.4 − 20.11 End-of-Chapter exercises: 15, 19, 24, 27, 29, 31, 41, 44, 46, 63, 64, 67, 86, 93 CD-ROM Chapter 20 Goals and Homework: 2a, 2c, 3a, 3c-e, 3g, 4a-b

You will be evaluated on the basic principles discussed in the chapters and some ‘Interchapters’: 1, 2, 3, 4, 5, 6, 7, 8, 16, 19, 20. Also prepare the Let’s Review summaries and questions in the text book for tests and examinations.


2014 CHM 172 STUDY GUIDE Critical Learning Outcomes The following outcomes were copied exactly from the document submitted to the Engineering Faculty for the accreditation of your degree courses. The following Engineering Council of South Africa (ECSA) exit-level outcomes are addressed in the module, i.e. at the conclusion of this module the student will be capable of:

ECSA: Problem Solving.

Each question asked must be analysed in terms of layered basic principles. Some thinking tools for solving problems in chemistry will be available on your web page.

ECSA : Application of scientific and engineering knowledge.

The application of fundamental principles and concepts of chemistry, to predict the behaviour and the properties of materials, and to understand the relationship between the internal structure of materials and their resultant properties.

ECSA : Investigations, experiments and data analysis.

Your lab sessions will teach you to observe and to make deductions within the basic principles of chemistry.

ECSA : Team and multi-disciplinary working.

It is required from students to work in groups and teams during some of the laboratory sessions and tutor classes in an effective and structured manner, which contribute to the development of certain interpersonal and communication skills. The submitted work though, must illustrate your own understanding of the principles, language and expression skills, copying will lead to disqualification.

ECSA : Lifelong learning

The development of learning skills, such as the understanding of fundamental concepts, scientific logic and reason, and the extensive use of the prescribed text book in their studies are emphasised in this module, which facilitates the capacity for lifelong learning.

ECSA : Independent learning.

The ability to take a text and make it your own with short notes and summations will be developed in the course. The lecturer will lead you to use electronic information via the web or your CD-ROM and printed materials and books to allow you to develop understanding within the chemical principles.



Outcomes of this Course The different themes are designed to achieve three major outcomes:

• How Chemical Compounds Determine Chemical Reactions • How Chemical Reactions Determine Thermodynamic Properties • How Electrochemistry Determines Thermodynamic values.

You will find a summary of the expected outcomes at the end of each chapter in the text book, see Chapter Goals Revisited

Syllabus theme 1: Matter & Measurement Candidates must understand and apply the principles, rules, conventions and theories according to which chemical compounds and their structures are described. You are expected to

• classify and describe matter qualitatively. • use the tools of quantitative Chemistry, the units and unit conversions; • use significant figures in all calculations;

Syllabus theme 2: Atomic Model, Mole concept & Periodicity Candidates must understand the models used to describe atoms and compounds, based on the information in the Periodic Table. You are expected to

• explain how the atom is constituted; • distinguish isotopes and calculate relative atomic mass and isotope abundances; • correctly name chemical compounds; • interpret chemical names and formulas; • understand and use the atomic model of orbitals to allocate quantum numbers to

electrons; • understand the principles of periodicity to determine electron configurations and

predict the properties of a specific element; • understand the composition and structure of the Periodic Table;

Syllabus theme 3: Bonding & Molecular Geometry Candidates must understand the models used to describe compounds, based on atomic structure and elemental properties. You are expected to

• distinguish between ionic and covalent bonding; • understand the VSEPR model of chemical bonding and predict the geometry of

compounds and ions; • use the VSEPR model of bonding to predict if a compound will be polar; • use the elements of the periodic table and construct compounds with certain molecular

geometries. The Lewis molecular structures of many compounds, with the experimental data, are available on the course clickUP pages. Work through these examples for exam and test preparation. ((Follow the “Lewis structures” link on the CHM 172 clickUP page under “Additional Study material”. Then click on, for example, trigonal bipyramidal’s ‘examples’, to see a page with both the Lewis dot and Lewis line or Couper structures of PCl5 and the other molecules belonging to the AX5 group, etc.)


2014 CHM 172 STUDY GUIDE Syllabus theme 4: Compounds and Formula Stoichiometry Candidates must understand the mole concept and apply it during the interpretation of the formulas of compounds. You are expected to

• apply the mole concept for elements and compounds; • determine chemical formula from analytical data: mass percentage and combustion

analysis

Syllabus theme 5: Chemical reaction equations Candidates must understand the format of chemical reaction equations and the need to classify reactions. You are expected to

• balance reaction equations; • identify types of reactions in aqueous solution; • interpret electron transfer reactions and balance these reaction equation with the half-

reaction method.

Syllabus theme 6: Reaction Stoichiometry You must be able to

• balance chemical reaction equations; • apply principles of stoichiometry in chemical reactions and calculations; • apply all stoichiometric principles to reactions in solutions.

Syllabus theme 7: Thermochemistry Candidates must understand the relationship between chemical reactions and energy and how it is represented in thermochemical reaction equations.You must be able to

• apply and use aspects of heat transfer and the units involved; • understand energy changes during phase changes; • determine enthalpy of formation and enthalpy changes of reactions; • apply Hess’s law; • understand state functions;

Syllabus theme 8: Equilibrium and Thermodynamics You must be able to

• Identify a system at equilibrium and the relationship between the amounts of reactants and products;

• understand product and/or reagent driven reactions; • understand the concepts, and obtain entropy and free energy values.

Syllabus theme 9: Electrochemistry You must be able to

• understand redox reactions; • balance redox reaction equations; • apply principles of stoichiometry in redox reactions and calculations; • do redox titrations; • construct/determine the potential/apply the uses of electrochemical cells; • obtain qualitative and quantitative information from standard reduction potentials; • apply the Nernst equation; • apply thermodynamic relationships; • understand electrochemistry: batteries, corrosion, electrolysis.



Study Themes Assignments for all themes: Exercises within the chapter as well as problems at the end of the chapter, also do the higher-numbered problems (more difficult) and apply in all future calculations. Also refer to the prescribed exercises in the Syllabus table on p. 10

Theme 1: Matter & Measurement

Study Chapter 1 and Additional Study Material: Appendices A and C in the text book. When you have mastered this study unit theme, you should have achieved all the goals stated in the Chapter Goals Revisited at the end of the chapter in the textbook. Important:

• Qualitative description of matter; • Conversion of one unit into another; • Relationships between units; • Significant figures; • Use of percentages.

Theme 2: Atomic model, Compounds & Periodicity of elements

Study units 2.1 & 2.2: Elements in the Periodic Table, Atomic Structure & Mass; Mole concept and Nomenclature

Study Chapter 2.1 – 2.8 as well as the rules and tables on p19 to p23 of this study guide. When you have mastered this study unit theme, you should have achieved all the goals stated in the Chapter Goals Revisited at the end of the chapter in the textbook. Historical facts are not for examination. Important:

• Isotopic Abundance; • Atomic mass; • Periodic Table; • Charges on ions; • Nomenclature;

Study unit 2.3: Atomic Structure, Quantum Numbers and Orbitals Study Chapter 6. When you have mastered this study unit theme, you should have achieved all the goals stated in the Chapter Goals Revisited at the end of the chapter in the textbook. Historical facts and personae are not for examination purposes. Important:

• Given the value of the principal quantum number, n, calculate all the values allowed for the other quantum numbers, ℓ , mℓ, and vice versa;

• State the representative subshell label for any given value of the angular momentum quantum number, mℓ;

• Draw the 3D shape of any given s, p or d orbital with respect to a set of axes.


2014 CHM 172 STUDY GUIDE Study unit 2.4: Electron Configurations and Periodicity Study Chapter 7. When you have mastered this study unit theme, you should have achieved all the goals stated in the Chapter Goals Revisited at the end of the chapter in the textbook. Understand and apply in examples

• Spin quantum number and magnetic properties; • Implications of Pauli principle and Hund’s rule; • Electron configurations and the different notations; • Multi-electron model of the atom: effective nuclear charge; • Electron filling in multi-electron systems; • The role of Z*, n, and ion charges in periodic properties; • Period and group relationships of atomic properties.

Theme 3: Bonding and Molecular Geometry

Study Chapter 8. Replace “Drawing Lewis Electron Dot Structures” on p349- 354 in the text book, with Lewis Structures, this Study Guide, p24. The method in the study guide will be followed as it differs from that in the text book. When you have mastered this study unit theme, you should have achieved all the goals stated in the Chapter Goals Revisited at the end of the chapter in the textbook. Important:

• Bonding models; • Covalent bonding. Drawing of Lewis structures by sharing electrons. The individual

contribution of each atom’s electrons is emphasized, see guidelines in this study guide;

• Prediction of the electronic and molecular geometries (using the Valence Shell Electron Pair Repulsion theory), polarity, bond lengths, bond angles, presence of dipole moments;

• Resonance structures.

Theme 4: Compounds and Formula Stoichiometry

Study Chapter 2.9-2.11 & Chapter 4.4 Important:

• Mole concept; • Percentage composition; • Calculation of Empirical and Molecular Formulae; • Combustion analysis • Hydrated compounds.


2014 CHM 172 STUDY GUIDE Theme 5: Chemical Reaction Equations

Study unit 5.1: Types of Chemical Reactions Study Chapter 3. When you have mastered this study unit theme, you should have achieved all the goals stated in the Chapter Goals Revisited at the end of the chapter in the textbook. Historical facts are not for examination. Important: • Balance chemical equations; • Write total ionic, net-ionic and molecular equations for reactions in aqueous solution; • Writing balanced reaction equations of the following reaction types: precipitation, acid-

base, gas-forming and oxidation-reduction.

Study unit 5.2: Balancing Redox reactions in acid and base solutions Study Chapter 20.1 as well as p26 of this Study Guide. When you have mastered this study unit theme, you should have achieved all the goals stated in the Chapter Goals Revisited at the end of the chapter in the textbook. Important: • Assign oxidation states to all elements on both sides of a redox reaction equation. • Balance redox reactions in acidic and basic medium with or without spectator ions

using the half-reaction method.

Theme 6: Reaction Stoichiometry

Study Chapter 4 When you have mastered this study unit theme, you should have achieved all the goals stated in the Chapter Goals Revisited at the end of the chapter in the textbook.

Important: • Apply mathematically the concept of ratios to determine Mass Relationships; • Limiting reagents; • Percentage yield; • Percentage purity of materials; • Quantitative aspects of concentrations and titrations.

Theme 7: Thermochemistry

Study Chapter 5 When you have mastered this study unit theme, you should have achieved all the goals stated in the Chapter Goals Revisited at the end of the chapter in the textbook. You must know and understand • How to use energy units and aspects of heat transfer; • Energy changes between the surroundings and systems; • Energy changes during phase changes; • Enthalpy of formation, enthalpy changes during reactions; • Applications of Hess’s law; • State functions; • Applications of calorimetry.


2014 CHM 172 STUDY GUIDE Theme 8: Equilibrium & Thermodynamics

Study Chapters 16.1, 16.2, 17.4, 18.4. When you have mastered this study unit theme, you should have achieved all the goals stated in the Chapter Goals Revisited at the end of the chapter in the textbook. You must know and understand • How equilibrium processes determines the thermodynamic outcome of a reaction • When reactions are product or reagent driven; • Thermodynamic vs kinetic aspects of reactions; • Entropy and entropy changes; • Free energy and free energy changes, Gibbs; • Product and reagent driven reactions; • Thermodynamic equilibrium constant calculations.

Assignments: Exercises within the chapter as well as problems at the end of the chapter, also do the higher-numbered problems (more difficult).

Theme 9: Electrochemistry

Study Chapter 20. When you have mastered this study unit theme, you should have achieved all the goals stated in the Chapter Goals Revisited at the end of the chapter in the textbook. Important • Electrochemical cells, electrodes and cell potentials; • Standard reduction potentials; • Non-standard conditions: Nernst equation; • Applications: electrolysis.

Assignments: Exercises within the chapter as well as problems at the end of the chapter, also do the higher-numbered problems (more difficult).



ADDITIONAL STUDY MATERIAL

NOMENCLATURE

A method based on differences in electronegativities is used to name compounds. 1. Elements are named according to the name given to the corresponding atom on the

Periodic Table. Example: Fe = iron; S = sulfur. 2. Mono-atomic cations obtain the same name as that given to the metal from which it was

formed. Ca2+ = Calcium ion. Transition metal cations may be found in different oxidation states. The Stock notation is used to discriminate between different oxidation states. Hence, the oxidation state of the atom, given in Roman numerals in brackets, is included after the element name. Example iron: iron(II) and iron(III), or Fe(II) and Fe(III).

3. Mono-atomic anions will display the stem part of the element name + a suffix -ide ,

example: C4− = carbide, Cℓ− = chloride and N3− = nitride. Poly-atomic anions are named according to a different system of rules (see 6 below).

4. Compounds which consist of only two different types of atoms are written in such a

manner that the least electronegative (more electropositive) element is given first in the name or formula followed by the more electronegative element. The rules for ions will apply with the “cation” the least electronegative and the “anion” the more electronegative element. The “cation” will be given the name of the element on the Periodic Table and the “anion” the stem + ending ide as in points 2 and 3 above. Examples: Li3N = lithiumnitride, Al2O3 = aluminiumoxide, NaBr = sodiumbromide, KH = potassiumhydride, etc.). The corresponding acids are named accordingly, but with the suffix -ic instead of ide and for hydrogen we use the abbreviation hydro; the word acid will be added to emphasize the acid property. Examples: HBr = hydrobromic acid , H2S = hydrosulfuric acid, etc. Trade names are often used for acids and may be confusing.

5. For covalent compounds the prefixes di-, tri-, tetra-, penta-, hexa-, hepta-, octa-, nona-

and deca- are used to designate the number of atoms of a certain kind in the compound. Examples: N2O5 = dinitrogenpenta-oxide, S2F10 = disulfurdecafluoride, etc,.

6. Oxo-anions (as such or in compounds) are named according to a different procedure. If

the element is in its highest oxidation state for the group (groups 14, 15 and 16), the name is formed by combining a stem part of the element name + the suffix -ate . This is seen as the parent name and other oxo-anions are deducted in a systematic manner by introducing different pre and affixes to the stem to indicate a central atom in a lower oxidation state (see the scheme below the table). Because of more possibilities for group 17 elements, the parent is taken as being in oxidation state +5 and for lower oxidation states the same rules apply as before, but for higher oxidation states a prefix per is added. Example: parent = stem + -ate (CℓO3

− = chlorate) Cℓ(VII) in CℓO4− per + stem + ate =

perchlorate) . Acids deducted from the oxo-anions are also named accordingly (table and scheme). The element name is sometimes rather used than the stem, -ic replaces -ate and -ous replaces -ite (compare 4 and below the table) and hydrogens are excluded, but acid is



added afterwards. Examples: sulfuric acid, chloric acid, chlorous acid, phosphoric acid etc,.

7. If hydrogen atoms as electropositive elements are included with oxo-anions in the same

formula, the combined anion is named according to rules 2, 5 and 6. Examples: H2PO4− =

dihydrogenphosphate; HSO3− = hydrogensulfite.

Summary of system used in naming anions, oxo-anions and oxo-acids:

Group 14 (4) Group 15 (5) Group 16 (6) Group 17 (7)

C: carb- C4−: carbide CO3

2−:carb(on)ate H2CO3: carbonic acid

N: nitr- N3−: nitride NO3

− : nitrate HNO3: nitric acid

O: ox- O2− : oxide

F: fluor- F-: fluoride

P: phosph- P3−: phosphide PO4

3− : phosphate H3PO4: phosphoric acid

S: sulf- S2− : sulfide SO4

2− : sulfate H2SO4: sulfuric acid

Cℓ: chlor- Cℓ−: chloride CℓO3

− : chlorate HCℓO3: chloric acid

As: arsen- As3− : arsenide AsO4

3− : arsenate H3AsO4: arsenic acid

Se: selen- Se2− : selenide SeO4

2− : selenate H2SeO4: selenic acid

Br: brom- Br− : bromide BrO3

−: bromate HBrO3: bromic acid

Te: tellur- Te2− : telluride TeO4

2− : tellurate H2TeO4: telluric acid

I: iod- I−: iodide IO3

− : iodate HIO3: iodic acid

Guidelines in terms of oxidation numbers (n)

Starting point: stem+ate (anion) and stem-acid (Oxoacid) Oxidation number (n) allocated the stem-ate name for the anion: Group 7, n = 5 Group 6, n = 6 Group 5, n = 5

Oxidation number: n+2 n n-2 n-4

Oxo-anions: per-stem-ate stem-ate stem-ite hipo-stem-ite

Oxo-acids: per-stem-acid stem-acid stem-ous-acid hipo-stem-ous-acid

Example: Chlorine, Group 7, n=5

Oxidation number on Cℓ: 3 5 3 1

Oxo-anions: perchlorate chlorate chlorite hipochlorite

Oxo-acids: perchlor acid chloor acid chlorous acid hipochlorous acid



NAMES OF THE ELEMENTS Z Symbol English Afrikaans 1 H hydrogen waterstof 2 He helium helium 3 Li lithium litium 4 Be beryllium berillium 5 B boron boor 6 C carbon koolstof 7 N nitrogen stikstof 8 O oxygen suurstof 9 F fluorine fluoor 10 Ne neon neon 11 Na sodium natrium 12 Mg magnesium magnesium 13 Al aluminium aluminium 14 Si silicon silikon 15 P phosphorus fosfor 16 S sulfur swael 17 Cℓ chlorine chloor 18 Ar argon argon 19 K potassium kalium 20 Ca calcium kalsium 21 Sc scandium skandium 22 Ti titanium titaan 23 V vanadium vanadium 24 Cr chromium chroom 25 Mn manganese mangaan 26 Fe iron yster 27 Co cobalt kobalt 28 Ni nickel nikkel 29 Cu copper koper 30 Zn zinc sink 31 Ga gallium gallium 32 Ge germanium germanium 33 As arsenic arseen 34 Se selenium seleen 35 Br bromine broom 36 Kr krypton kripton 37 Rb rubidium rubidium 38 Sr strontium stronsium 39 Y yttrium yttrium 40 Zr zirconium sirkonium 41 Nb niobium niobium 42 Mo molybdenum molibdeen 43 Tc technetium tegnesium 44 Ru ruthenium rutenium 45 Rh rhodium rodium 46 Pd palladium palladium 47 Ag silver silwer 48 Cd cadmium kadmium 49 In indium indium 50 Sn tin tin 51 Sb antimony antimoon 52 Te tellurium telluur 53 I iodine jodium 54 Xe xenon xenon 55 Cs cesium sesium 56 Ba barium barium

Z Symbol English Afrikaans 57 La lanthanum lantaan 58 Ce cerium serium 59 Pr praseodymium praseodimium 60 Nd neodymium neodimium 61 Pm promethium prometium 62 Sm samarium samarium 63 Eu europium europium 64 Gd gadolinium gadolinium 65 Tb terbium terbium 66 Dy dysprosium disprosium 67 Ho holmium holmium 68 Er erbium erbium 69 Tm thulium tulium 70 Yb ytterbium ytterbium 71 Lu lutecium lutesium 72 Hf hafnium hafnium 73 Ta tantalum tantaal 74 W tungsten wolfram 75 Re rhenium renium 76 Os osmium osmium 77 Ir iridium iridium 78 Pt platinum platinum 79 Au gold goud 80 Hg mercury kwik 81 Tl thallium tallium 82 Pb lead lood 83 Bi bismuth bismut 84 Po polonium polonium 85 At astatine astaat 86 Rn radon radon 87 Fr francium frankium 88 Ra radium radium 89 Ac actinium aktinium 90 Th thorium torium 91 Pa protactinium protaktinium 92 U uranium uraan 93 Np neptunium neptunium 94 Pu plutonium plutonium 95 Am americium amerisium 96 Cm curium curium 97 Bk berkelium berkelium 98 Cf californium kalifornium 99 Es einsteinium einsteinium 100 Fm fermium fermium 101 Md mendelevium mendelevium 102 No nobelium nobelium 103 Lr lawrencium lawrensium 104 Rf rutherfordium rutherfordium 105 Db dubnium dubnium 106 Sg seaborgium seaborgium 107 Bh bohrium bohrium 108 Hs hassium hassium 109 Mt meitnerium meitnerium



NAMES OF IONS (alphabetical English names)

Naam Name Formule Formula

asetaat acetate CH3COO− amied amide NH2¯ ammonium ammonium NH4

+ arsenied arsenide As3− arsenaat arsenate AsO4

3− arseniet arsenite AsO3

3− asied azide N3

− boraat borate BO3

3− boried boride B3−

bromaat bromate BrO3¯ bromiet bromite BrO2¯ karbied carbide C4− karbonaat carbonate CO3

2− chloraat chlorate CℓO3¯ chloriet chlorite CℓO2¯ chromaat chromate CrO4

2− sianaat cyanate NCO¯ sianied cyanide CN¯ dichromaat dichromate Cr2O7

2−

diwaterstoffosfaat dihydrogen phosphate H2PO4

−

disulfied disulfide S22−

fluoried fluoride F− hidrasied hydrazide N2H3

− hidrasonium hydrazonium N2H5

+ hidried hydride H− waterstofkarbonaat (bikarbonaat)

hydrogen carbonate (bicarbonate) HCO3

−

waterstofsulfaat hydrogen sulfate HSO4−

waterstoffosfiet hydrogen phosphite HPO32−

waterstoffosfaat hydrogen phosphate HPO42−

waterstofsulfied hydrogen sulfide HS− waterstofsulfiet hydrogen sulfite HSO3

−

Naam Name Formule Formula

hidronium (oksonium)

hydronium (oxonium) H3O+

hidroksied hydroxide OH− hiperoksied hyperoxide O2

− hipobromiet hypobromite OBr− hipochloriet hypochlorite OCℓ− hipojodiet hypoiodite OI¯ jodaat iodate IO3

−

jodied iodide I− jodiet iodite IO2

− nitraat nitrate NO3

− nitried nitride N3− nitriel nitrile NO2

+ nitriet nitrite NO2

− nitrosiel nitrosyl NO+ oksalaat oxalate C2O4

2− oksied oxide O2− osonied ozonide O3

− perbromaat perbromate BrO4¯ perchloraat perchlorate CℓO4¯ perjodaat periodate IO4

− permanganaat permanganaat MnO4

− peroksied peroxide O2

2− fosfaat phosphate PO4

3− fosfied phosphide P3− sulfaat sulfate SO4

2− sulfied sulfide S2− sulfiet Sulfite SO3

2− tiosianaat thiocyanate NCS¯ tiosulfaat thiosulfate S2O3

2− trijodied triiodide I3

−



NAMES OF SOME COMMON COMPOUNDS Formula Name Naam

Acids / Sure HCℓ (aq) hydrochloric acid soutsuur HF (aq) hydrofluoric acid hidrofluoorsuur HBr(aq) hydrobromic acid hidrobroomsuur HI (aq) hydroiodic acid hidrojoodsuur H2SO4 sulfuric acid swaelsuur H2SO3 sulfurous acid swaeligsuur HNO3 nitric acid salpetersuur HNO2 nitrous acid salpetrigsuur HCℓO4 perchloric acid perchloorsuur HCℓO3 chloric acid chloorsuur HCℓO2 chlorous acid chlorigsuur HCℓO hypochlorous acid hipochlorigsuur HBrO4 perbromic acid perbroomsuur HBrO3 bromic acid broomsuur HBrO2 bromous acid bromigsuur HBrO hypobromous acid hipobromigsuur H3PO4 phosphoric acid fosforsuur CH3COOH acetic acid asynsuur H2CO3 carbonic acid koolsuur

Binary compounds / Binêre verbindings HBr hydrogen bromide waterstofbromied HCℓ hydrogen chloride waterstofchloried HF hydrogen fluoride waterstoffluoried H2S hydrogen sulfide waterstofsulfied Na2S sodium sulfide natriumsulfied NH3 ammonia ammoniak CaBr2 calcium bromide kalsiumbromied

Ionic compounds with oxyanions and/or ammonia Ioniese verbindings met oksi-anione en/of ammoniak

NaOH sodium hydroxide natriumhidroksied KMnO4 potassium

permanganate kaliumpermanganaat

Na2CrO4 sodium chromate natriumchromaat Na2S2O3 sodium thiosulfate natriumtiosulfaat FeSO4 iron(II) sulfate yster(II)sulfaat Fe2(SO4)3 iron(III) sulfate yster(III)sulfaat

Formula Name Naam NH4Cℓ ammonium chloride ammoniumchloried Na2SO4 sodium sulfate natriumsulfaat Na2SO3 sodium sulfite natriumsulfiet KNO3 potassium nitrate kaliumnitraat KNO2 potassium nitrite kaliumnitriet LiCℓO4 lithium perchlorate litiumperchloraat LiCℓO3 lithium chlorate litiumchloraat LiCℓO2 lithium chlorite litiumchloriet LiCℓO lithium hypochlorite litiumhipochloriet (NH4)2SO4 ammonium sulfate ammoniumsulfaat NaC2H3O2 sodium acetate natriumasetaat Na2CO3 sodium carbonate natriumkarbonaat NaHCO3 sodium bicarbonate

sodium hydrogen carbonate

natriumbikarbonaat natriumwatersofkarbonaat

KBrO4 potassium perbromate

kaliumperbromaat

KBrO3 potassium bromate kaliumbromaat Ca(BrO2)2 calcium bromite kalsiumbromiet Ca(BrO)2 calcium hypobromite kalsiumhipobromiet Na2Cr2O7 sodium dichromate natriumdichromaat

Oxides / Oksiedes NO nitrogen(II) oxide

nitrogen monoxide stikstof(II)oksied stikstofmonoksied

N2O nitrogen(I) oxide dinitrogenoxide

stikstof(I)oksied distikstofoksied

NO2 nitrogen(IV) oxide nitrogen dioxide

stikstof(IV)oksied stikstofdioksied

N2O5 nitrogen(V) oxide dinitrogen pentoxide

stikstof(V)oksied distikstofpentoksied

CO carbon monoxide koolstofmonoksied CO2 carbon dioxide koolstofdioksied Na2O sodium oxide natriumoksied KO2 potassiumhyperoxide kaliumhiperoksied Na2O2 sodium peroxide natriumperoksied H2O2 hydrogen peroxide waterstofperoksied



, .

LEWIS STRUCTURES The following set of guidelines are useful when drawing Lewis structures. The method described here is based on the Valence Bonding Model, and differs from the method suggested by the prescribed text book (Kotz and Treichel). The text book method prescribes that the valence electrons of all the atoms in the compound be added together, and then spread over the entire compound, in the form of bond- and lone electron pairs.

You must differentiate between the LEWIS DOT and LEWIS LINE or COUPER Structures. To indicate the pre4sence of a dipole moment in a molecule, it is suggested that the LEWIS LINE or COUPER structures are always drawn dimensionally correct. The method presently being suggested keeps the electrons of each atom apart, before making covalent- and dative covalent bonds between the atoms. This method is a much better method than the simpler text book method, as it produces results that reflect the character of each atom in the compound much more accurately and illustrates your understanding of the electronic model. The method entails four steps consecutively executed, the details of which are discussed below: Step 1. Atomic building blocks Step 2. Method of forming bonds according to the octet rule (8 electron rule) Step 3. Octet rule not obeyed Step 4. Critically re-evaluate of proposed structure by comparison with the

experimental structure 1. Atom Building Blocks 1.1 Select the most electropositive element as central atom.

Your choice will be simplified if you bear in mind that the most electropositive element is usually placed first in the molecular formula (see p17 of this Guide). Hydrogen is an important exception. Strictly speaking, hydrogen can form only one covalent bond, since it has only one electron in its 1s orbital available for sharing. Hydrogen is therefore always placed in a terminal position in the arrangement of atoms.

1.2 Write down the atom symbol of each element and indicate valence shell electrons

around the symbol of each respective atom. Depict the valence electrons of each atom with a different symbol; i.e. use dots, squares, crosses, circles, etc.

1.3 If the compound is a cation, place the positive charge on the most electropositive atom.

Bear in mind that a positive charge implies that an electron was removed from the valence shell of the atom. In the case of the IF4

+ cation, the positive charge must be on I (more electropositive than F), and the symbol will be: I+

If the compound is an anion, place the negative charge on the most electronegative element. The negative charge implies that an extra electron has been added to the valence shell of the atom. In the case of the IF2¯ anion, the negative charge is placed on F, and the symbol is: F¯ When the compound carries a multiple charge, this charge must be spread over as many atoms as possible of the most electronegative element, and not placed on a single atom alone. In the case of the sulfate ion, SO4

2−, the two negative charges are placed on two separate oxygen atoms (O more electronegative than S): O¯ and O− rather than O2−.



2. Bond Formation NB: The approach in this section is that the octet rule (8 electron rule) must be obeyed. After every action the premise of obeying the octet rule is tested. To limit errors it is advisable to execute the steps below in the given sequence. 2.1 Firstly, make single bonds. One single bond between an unpaired electron on the central

atom and a terminal atom (or fragment) needing only one electron to fill its valence shell (see Octet Rule KP p368) is performed. Count the valence electrons around the central atom. If all the terminal atoms are bound, and each atom in the structure has a complete octet, the structure is complete. If not, proceed to step 2.2.

2.2 Secondly, an atom may need two electrons for a filled valence shell. After the first bond

is made, make a double bond between a second unpaired electron on the central atom and the terminal atom needing two electrons to fill its valence shell. Count the valence electrons around the central atom. If all the terminal atoms are bound, and each atom in the structure has a complete octet, the structure is complete. If not, proceed to step 2.3.

2.3 Thirdly, after 2.2 and the terminal atom needs a third electron for a filled octet, make a

triple bond between a third unpaired electron on the central atom and a third electron on the terminal atom needing three electrons to fill its valence shell. If all the terminal atoms are bound, and each atom in the structure has a complete octet, the structure is complete. If not, proceed to step 2.4.

2.4 Fourthly, if the central atom has a complete octet at this stage but terminal atoms needing

two electrons are not yet bonded, a dative covalent bond from a lone electron pair on the central atom can be used to supply the two electrons to the terminal atom. If all the terminal atoms are bound, the structure is complete. If not, the octet of the central atom must be extended or a different bonding theory, such as the molecular orbital theory, must be used (this does not form part of this course). Continue to step 3:

3. Octet Rule is not obeyed There are three possible situations where the octet rule cannot be obeyed. They are: (i) there are not enough electrons on the central atom, (ii) there are an uneven number of electrons in the valence shell of the atoms which must be bonded and (iii) there are too many electrons. When the central atom have empty d-orbitals (main group elements of period 3 and higher) in the valence shell they can also be used for bonding and the octet rule are extended to a maximum of 18 electrons. As a result of extending the octet rule, paired electrons on the central atom can be excited to empty d-orbitals and more bonds are possible. Also, applying rule 2.4 above becomes unnecessary as one electron of the lone pair is excited to an empty d-orbital and therefore a dative covalent bond is replaced by a double bond. Lewis structures not obtainable under step 2 will be done in the following manner: (i) Not enough electrons: The central atom has too few electrons for the octet rule to be

obeyed (Be, etc.) Arguably, dative covalent bonds of terminal atoms could solve this problem for the central atom. However, this will imply that electron pairs from more electronegative atoms are donated to more electropositive atoms. The real solution is found in other bonding models.

(ii) Uneven number of electrons: the valence bond theory require two electrons per bond. With an uneven number of electrons this is impossible. Other bonding models such as the molecular orbital model does not require two electrons per bonding orbital (this theory will not be part of this year’s curriculum). If, in spite of this, you want to draw Lewis structures, the odd electron will be placed above a bond or on the central (more



electropositive) atom. (iii) Extended octet:

Only allowed if empty d-orbitals are available on the central element. Complete the Lewis structure as follows:

3.1 Make a single bond from a newly excited unpaired electron on the central atom to

each remaining terminal atom (or fragment) needing only one electron to fill its valence shell. If all the terminal atoms are bound, the structure is complete. If not, proceed with step 3.2.

3.2 Make a double bond from two, one newly excited, unpaired electrons on the

central atom to each remaining terminal atom needing two electrons in its valence shell. If the structure is still not complete, proceed with step 3.3.

3.3 If any unbound terminal atoms still remain, these are most probably halide ions, X−,

each with a complete octet. Attach the halide ion(s) to the central atom with a dative covalent bond from the halide to an empty orbital on the central atom.

4. Critically Re-evaluate Structure The final Lewis structure should, ideally speaking, be compared to the experimentally determined structure of the compound. In some cases more than one possible Lewis structure can be drawn to represent a specific compound. The different possibilities are called contributing structures, and formal charges can be used to select the most probable structure from a set of possible structures. Sometimes the valence bond theory is not the right model to apply to a specific molecule and poor comparisons are obtained.

BALANCING REDOX REACTIONS

Balancing redox reaction equations using the ion electron method implies that the nature of the reaction medium is known. In aqueous medium this could be under acidic or basic conditions. By careful examining of the species in the reaction equation it is possible, in most cases, to deduct the nature of the medium.

Acid medium: Evidence for an acidic medium is found in the presence of an acid (or H+)

and/or protonated anions (HX, HXn-, etc.) in the equation. Basic medium: Evidence for a basic medium is found in the presence of OH- and/or unprotonated anions in the equation.

The following method can be used 1. Identify the given equation as a redox reaction: Determine the oxidation number

(ON) of each element in every compound involved in the reaction. If the ON of certain elements change during the reaction, it can be classified as a redox reaction. Take note of the reaction medium. The presence of H+ indicates an acid medium, whereas the presence of OH− indicates a basic medium.

2. Divide the reaction equation into two half reactions: The element(s) experiencing an increase in ON is (are) oxidised, whereas the element(s) experiencing a decrease in ON is (are) reduced.

3. Balance the atoms in each half reaction separately: First, balance all atoms other than oxygen and hydrogen. Then, balance any shortage of oxygen atoms. For this the method depends on the reaction medium. For acid mediums the combination H+/H2O and for basic mediums the combination OH-/H2O are used. See diagram below which



shows the preferred method (and differs from the textbook method)

4. Balance the charges in each half reaction separately: Add electrons (e−) to the side where positive charges need to be neutralised or where a shortage of electrons exist The net charge must be the same on both sides of the equation.

5. Balance the two half reactions stoichiometrically: Multiply each half reaction with a suitable stoichiometric factor, in order that the number of electrons lost during oxidation equals the number of electrons gained during reduction.

6. Add the two half reactions together to find the balanced net redox reaction equation.

Cancel the electrons on both sides of the equation, as well as any other chemical species occurring on both sides of the equation.

7. Add spectator ions, if initially present.

8. Test your answer: Make certain that the atoms and charges on both sides of the equation balance, and that the correct reaction medium was used.

Summary of half-reaction method for balancing redox reactions in acidic or basic medium

Assign oxidation states to all the elements on both sides of the reaction equation

Identify and write the oxidation and reduction half-reactions without spectator ions

ACID medium

Balance all elements except O and H

To balance O add one H2O for each O needed

To balance H add one H+ for each H needed

Balance the charge with e-

Make the number of electrons in each half-reaction the same by multiplying all coefficients

with an appropriate number

Combine and simplify

Add and balance spectator ions, check

BASE medium

Balance all elements except O and H

To balance O add one H2O for each O needed

To balance H add one H2O for each H needed AND add the same number of OH- on the other side (net gain of 1 H on

side where H2O was added).

Combine (H+ and OH-) on same side to form water. Balance the charge with e-


2014 CHM 172 STUDY GUIDE CALENDAR CHM 172 SECOND SEMESTER 2014

Week # MONDAY TUESDAY WEDNESDAY THURSDAY FRIDAY

JULY

14 Recess 15 Recess 16 Recess 17 Recess 18 Recess

1 21 A & B:

Lab Orientation Collect model kits

22 clickUP PAGE

Lab Safety Quiz - Already open

OWL REGISTRATION 23

clickUP PAGE Lab Safety Quiz -

Already open OWL REGISTRATION

24 Lab Orientation Collect model kits 25 Lab Safety Quiz

CLOSES 27/7

2 28 A: P1 B: T1 29 30 31 A: P1 B: T1 1

AU

GU

ST 3 4 A: T1 B: P1 5 6 7 A: T1 B: P1 8

4 11 A: T2 LAB

B: T2 HALL 12 13 14 A: T2

LAB B: T2 HALL 15

5 18 TEST WEEK 1 19 TEST WEEK 1 20 TEST WEEK 1 21 TEST WEEK 1 22 TEST WEEK 1 6 25 A: P2 B: T3 26 27 28 A: P2 B: T3 29

SEPT

EMB

ER 7 1 A: T3 B: P2 2 3 4 A: T3 B: P2 5

8 8 WEDNESDAY TT 9 10 SPRING DAY 11 A: P3 B: T4 12

9 15 A: P3 B: T4 16 17 18 A: T4 B: P3 19

10 22 A: T4 B: P3 23 WEDNESDAY TT 24 HERITAGE DAY 25 A: P4 B: T5 26

OC

TOB

ER

11 29 TEST WEEK 2 30 TEST WEEK 2 1 TEST WEEK 2 2 TEST WEEK 2 3 TEST WEEK 2

6 RECESS 7 RECESS 8 RECESS 9 RECESS 10 RECESS

12 13 A: P4 B: T5 14 15 16 A: T5 B: P4 19

13 20 A: T5 B: P4 21 22 23 A: P5 B: T6 24 14 27 A: P5 B: T6 28 29 30 A: T6 B: P5 31

NO

VEM

BER

15 3 A: T6 B: P5 4 Lectures end 5 6 SICK PRAC 7 Exams start

10 11 12 13 14

17 18 19 20 21

24 25 26 27 28 Supps start

Dec 1 2 3 4 5 Academic year ends

Timetable Groups

G01/B/P1 Mon A 14h30 – 17h20 INFORMATION Sessions allocated on Engineering Faculty timetable Lab workstation & Monday A or B group on CHM 172 clickUP page P1 to P5 = laboratory session (practical) ASSESSMENT: Lab report T1 to T6 = tutorial session ASSESSMENT: Tutorial test

G02/B/P1 Mon B 14h30 – 17h20

G03/B/P3 Thu 14h30 – 17h20

Week #

Monday Group (14h30 – 17h20) Date Thursday Group

(14h30 – 17h20) Date Group A Date Group B

1 21/7 Laboratory Orientation (Laboratories) Quiz 1 Laboratory rules (own time) 21/7 Laboratory Orientation (Laboratories)

Quiz 1 Laboratory rules (own time) 24/7 Laboratory Orientation (Laboratories) Quiz 1 Laboratory rules (own time)

2 28/7 P1: Measurement (Laboratories) 28/7 T1: Atomic structure / Virtual lab

(Large Chemistry Hall ) 31/7 P1: Measurement (Laboratories)

3 4/8 T1: Atomic structure / Virtual lab (Large Chemistry Hall) 4/8 P1: Measurement

(Laboratories) 7/8 T1: Atomic structure / Virtual lab (Large Chemistry Hall)

4 11/8 T2: Model Building session (Lecture halls & labs) 11/8 T2: Model Building session

(Lecture halls & labs) 14/8 T2: Model Building session (Lecture halls & labs)

6 25/8 P2: Reactions in aqueous 25/8 T3: Mole Concept & Nomenclature 28/8 P2: Reactions in aqueous

7 1/9 T3: Mole Concept & Nomenclature 1/9 P2: Reactions in aqueous 4/9 T3: Mole Concept & Nomenclature

8 8/9 WEDNESDAY TIMETABLE 8/9 WEDNESDAY TIMETABLE 11/9 P3: Acid-Base titration

9 15/9 P3: Acid-Base titration 15/9 T4: Reactions & Stoichiometry 18/9 T4: Reactions & Stoichiometry

10 22/9 T4: Reactions & Stoichiometry 22/9 P3: Acid-Base titration 25/9 P4: Redox titration

12 13/10 P4: Redox titration 13/10 T5: Thermochemistry 15/10 T5: Thermochemistry

13 20/10 T5: Thermochemistry 20/10 P4: Redox titration 23/10 P5: Thermochemistry

14 27/10 P5: Thermochemistry 27/10 T6: Equilibrium & Thermodynamics 30/10 T6: Equilibrium & Thermodynamics

15 3/11 T6: Equilibrium & Thermodynamics 3/11 P5: Thermochemistry

OWL (Online Web Learning): Weekly OWL exercises are done in your own time. Check the deadlines!!


2014 CHM 172 STUDY GUIDE INFORMATION PAGE The Periodic Table of the Elements

1 H

1.01

2 He

4.00 3 Li

6.94

4 Be

9.01

5 B

10.81

6 C

12.01

7 N

14.01

8 O

16.00

9 F

19.00

10 Ne

20.18 11 Na

22.99

12 Mg

24.31

13 Al

26.98

14 Si

28.09

15 P

30.97

16 S

32.07

17 Cl

35.45

18 Ar

39.95 19 K

39.10

20 Ca

40.08

21 Sc

44.96

22 Ti

47.87

23 V

50.95

24 Cr

52.00

25 Mn

54.94

26 Fe

55.85

27 Co

58.93

28 Ni

58.69

29 Cu

63.55

30 Zn

65.39

31 Ga

69.72

32 Ge

72.61

33 As

74.92

34 Se

78.96

35 Br

79.90

36 Kr

83.80 37 Rb

85.47

38 Sr

87.62

39 Y

88.91

40 Zr

91.22

41 Nb

92.91

42 Mo

95.94

43 Tc

98.91

44 Ru

101.07

45 Rh

102.91

46 Pd

106.42

47 Ag

107.87

48 Cd

112.41

49 In

114.82

50 Sn

118.71

51 Sb

121.76

52 Te

127.60

53 I

126.90

54 Xe

131.29 55 Cs

132.91

56 Ba

137.33

57 La

138.91

72 Hf

178.49

73 Ta

180.95

74 W

183.84

75 Re

186.21

76 Os

190.23

77 Ir

192.22

78 Pt

195.08

79 Au

196.97

80 Hg

200.59

81 Tl

204.38

82 Pb

207.20

83 Bi

208.98

84 Po

208.98

85 At

209.99

86 Rn

222.01 87 Fr

223.02

88 Ra

226.03

89 Ac

227.03

104 Rf

261.11

105 Db

262.11

106 Sg

263.12

107 Bh

262.12

108 Hs 265

109 Mt 266

58

Ce 140.12

59 Pr

140.91

60 Nd

144.24

61 Pm

144.91

62 Sm

150.36

63 Eu

151.97

64 Gd

157.25

65 Tb

158.93

66 Dy

162.50

67 Ho

164.93

68 Er

167.26

69 Tm

168.93

70 Yb

173.94

71 Lu

174.97

90 Th

232.04

91 Pa

231.04

92 U

238.03

93 Np

237.05

94 Pu

244.06

95 Am

243.06

96 Cm

247.07

97 Bk

247.07

98 Cf

251.08

99 Es

252.08

100 Fm

257.10

101 Md

258.10

102 No

259.10

103 Lr

262.11

Electronegativity values of the elements according to the Pauling scale H

2.1 He

Li 1.0

Be 1.5 B

2.0 C

2.5 N

3.0 O

3.5 F

4.0 Ne

Na 0.9

Mg 1.2 Al

1.5 Si 1.8

P 2.1

S 2.5

Cl 3.0

Ar

K 0.8

Ca 1.0

Sc 1.3

Ti 1.5

V 1.6

Cr 1.6

Mn 1.5

Fe 1.8

Co 1.9

Ni 1.8

Cu 1.9

Zn 1.6

Ga 1.6

Ge 1.8

As 2.0

Se 2.4

Br 2.8

Kr 3.0

Rb 0.8

Sr 1.0

Y 1.2

Zr 1.4

Nb 1.6

Mo 1.8

Tc 1.9

Ru 2.2

Rh 2.2

Pd 2.2

Ag 1.9

Cd 1.7

In 1.7

Sn 1.8

Sb 1.9

Te 2.1

I 2.5

Xe 2.6

Cs 0.7

Ba 0.9 Hf

1.3 Ta 1.5

W 1.7

Re 1.9

Os 2.2

Ir 2.2

Pt 2.2

Au 2.4

Hg 1.9

Tl 1.8

Pb 1.9

Bi 1.9

Po 2.0

At 2.2

Rn

Fr 0.7

Ra 0.9

Equations Δ𝑈 = 𝑞 + 𝑤 𝑞 = 𝑚𝐶Δ𝑇 ∆𝑟𝐻𝑜 = ∑Δ𝑓𝐻𝑜 (𝑝𝑟𝑜𝑑) − ∑Δ𝑓𝐻𝑜 (𝑟𝑒𝑎𝑐𝑡) ∆𝑟𝑆𝑜 = ∑𝑆𝑜 (𝑝𝑟𝑜𝑑) − ∑𝑆𝑜 (𝑟𝑒𝑎𝑐𝑡) ∆𝑟𝐺𝑜 = ∑Δ𝑓𝐺𝑜 (𝑝𝑟𝑜𝑑) −∑Δ𝑓𝐺𝑜 (𝑟𝑒𝑎𝑐𝑡) Δ𝑆𝑢𝑛𝑖𝑣𝑜 = Δ𝑆𝑠𝑦𝑠𝑜 + Δ𝑆𝑠𝑢𝑟𝑟𝑜

𝑆𝑠𝑢𝑟𝑟𝑜 =𝑞𝑠𝑢𝑟𝑟𝑇 = −

∆𝐻𝑠𝑦𝑠𝑜

𝑇

Δ𝑟𝐺𝑜 = Δ𝑟𝐻𝑜 − 𝑇Δ𝑟𝑆𝑜 Δ𝑟𝐺 = Δ𝑟𝐺𝑜 + 𝑅𝑇𝑙𝑛𝑄 Δ𝑟𝐺𝑜 = −RT𝑙𝑛K 𝑙𝑛K = 2.303𝑙𝑜𝑔K 𝑙𝑛Q = 2.303𝑙𝑜𝑔Q

𝑤𝑚𝑎𝑥 = 𝑛ℱ𝐸 Δ𝑟𝐺𝑜 = −𝑛ℱ𝐸𝑜

𝐸 = 𝐸𝑜 −𝑅𝑇𝑛ℱ 𝑙𝑛Q

𝐸 = 𝐸𝑜 −0.0592𝑛 𝑙𝑜𝑔Q (25°C)

𝑙𝑜𝑔𝐾𝑒𝑞 =𝑛𝐸𝑜

0.0592 (25°𝐶)

Constants R = 8.3145 J⋅mol−1⋅K−1 = 8.3145 kPa⋅L⋅mol-1⋅K-1 = 0.082057 atm⋅L⋅mol-1⋅K-1

ℱ = 9.6485 x 104 C⋅mol−1 of/or 9.6485 x 104 J⋅V−1⋅mol−1

𝑒 = 1.602 x 10−19 C NA = 6.02213 × 1023

0°C = 273.15 K 1 cal = 4.184 J C (H2O(ℓ)) = 4.184 J⋅g−1⋅K−1 C (H2O(s)) = 2.06 J⋅g−1⋅K−1 C (H2O(g)) = 1.86 J⋅g−1⋅K−1 ∆𝑓𝑢𝑠𝐻𝑜(𝑤𝑎𝑡𝑒𝑟) = 6.02 𝑘𝐽 ∙ 𝑚𝑜𝑙−1 ∆𝑣𝑎𝑝𝐻𝑜(𝑤𝑎𝑡𝑒𝑟) = 40.65 𝑘𝐽 ∙ 𝑚𝑜𝑙−1

Conversion Factors 1 L = 10−3 m3 = 1 dm3 1 bar = 1.000 x 105 Pa 1 C = 1 Amp⋅1 sec

1 J = 0.2390 cal = 1 Pa⋅m3 = 1 m2⋅kg⋅s−2 = 1 V⋅C = 1 Watt⋅1 sec 1 atm = 1.013 x 105 N⋅m−2 = 1.013 x 105 Pa = 760 mm Hg = 760 torr


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