Changes in the syllabus content

Topic 1: Stoichiometric relationships
Time: 13.5 hours (previously 12.5 hours)
Addition Deletion Rationale
Introduction to elements, compounds, mixtures, chemical equations, states of matter, changes of state Standard temperature and pressure

New material was previously implicit

(and so does not represent an increase in teaching/learning)

Explanation of real gas behaviour Ideal gas equation (now given in the data booklet) Allows for NOS connection and deeper understanding of relation to particle theory
Homogeneous and heterogeneous phases Broadens scope for practical work and work in topics 7 and 17—equilibrium
Specific experimental work on deriving empirical formulas Prescribed practical
Standard solution and titration Prescribed practical
Topic 2: Atomic structure
Time: 6 hours (previously 4 hours)
Addition Deletion Rationale
Operation of the mass spectrometer The previous content was out-dated and over-simplified. Modern applications added to topic 11 and option A
Uses of named radioisotopes Recall-based learning
Electron configuration for atoms up to Z = 36 Moved from AHL so that all students use the same model
Electron arrangement up to Z = 20 No longer necessary as electron configuration added
Knowledge of series in different parts of the spectrum Recall-based learning reduced; now in the data booklet
Topic 3: Periodicity
Time: 6 hours (previously 6 hours)
Addition Deletion Rationale
Electron configuration from position in periodic table; use of group numbers from 1 to 18 Electron arrangement up to Z = 20 Alignment with changes in topic 2
Knowledge of group trends limited to alkali metals and halogens Similarities and differences in the chemical properties of elements in the same group Reduces the amount of recall required
Topic 4: Chemical bonding and structure
Time: 13.5 hours (previously 12.5 hours)
Addition Deletion Rationale
Resonance structures in organic chemistry Allows for links to topic 10
Graphene An important network covalent compound that was not well known when previous guide was produced
Use of the terms anion and cation These are used in topic 9 and topic 19
No significant deletions as the topic contains key chemical ideas that are applied elsewhere in the course Concepts remain the same but some of the rote memorization has been deleted
Topic 5: Energetics/thermochemistry
Time: 9 hours (previously 8 hours)
Addition Deletion Rationale
Standard enthalpy changes of reaction Moved from AHL
Bond energy calculations for ozone required as a specific example Provides a relevant link to environmental chemistry
No significant deletions as the topic contains key chemical ideas that are applied elsewhere in the course Concepts remain the same but some of the rote memorization has been deleted
Topic 6: Chemical kinetics
Time: 7 hours (previously 5 hours)
Addition Deletion Rationale
Potential energy profiles with and without catalysts; understanding of activation energy is specified Implied in previous syllabus but never explicitly stated
Prescribed practical to investigate rates Description of experiments to measure rates Although students are expected to understand and apply changes in mass, volume or colour to monitor rate, there is less emphasis on recall
No significant deletions as the topic contains key chemical ideas that are applied elsewhere in the course Concepts remain the same but some of the rote memorization has been deleted
Topic 7: Equilibrium
Time: 4.5 hours (previously 5 hours)
Addition Deletion Rationale
Reaction quotient, Q Enriches the current content by describing how a system changes as it moves towards equilibrium
Details of applications to industrial processes Concepts could still be applied to these examples but students are not expected to recall factual details
Topic 8: Acids and bases
Time: 6.5 hours (previously 6 hours)
Addition Deletion Rationale
Acid deposition Environmental application
pH calculations for strong and weak acids Creates a link to maths and allows quantitative chemistry for SL in this topic
Use of the pH meter and Universal Indicator paper Prescribed practical
Lewis theory Moved to AHL topic 18
Topic 9: Redox processes
Time: 8 hours (previously 7 hours)
Addition Deletion Rationale
Redox titration problems Provides opportunity for a deeper understanding in applications and skills. The mathematical concepts are the same as in topic 1 but in a different application
Application of the activity series to deduce the feasibility of a reaction This is not an addition in principle, but a means of reducing recall, or avoiding the use of the electrochemical series at this level
Biological oxygen demand (BOD) and the Winkler method Environmental application
No significant deletions as the topic contains key chemical ideas that are applied elsewhere in the course Concepts remain the same but some of the rote memorization has been deleted
Topic 10: Organic chemistry
Time: 11 hours (previously 12 hours)
Addition Deletion Rationale
Naming of esters Completes the naming of basic organic structures
Identification of general formulae Implicit in the old guide—now formally required
Identification of nitrile and akynyl functional groups Identification of functional groups no longer divided between core and AHL topics
Structure and bonding in benzene A more complete overview of organic chemistry, plus a link to topic 4
SN1 and SN2 mechanisms Moved to AHL
Reaction pathways Most synthetic pathways moved to AHL
Topic 11: Measurement and analysis
Time: 10 hours (previously 2 hours)
Addition Deletion Rationale
Descriptions of quantitative and qualitative data Previously implicit in lab work
Calculation of percentage error Previously implicit in lab work
Distinction between sketched and drawn graphs Added to clarify a distinction sometimes not apparent to students
Analytical techniques Moved from previous topics (10 and 20) and from option A to create a coherent sub-topic; operating principles are not required
Index of hydrogen deficiency Useful as part of the process of structure elucidation
Topic 12: Atomic structure
Time: 2 hours (previously 3 hours)
Addition Deletion Rationale
Electron configurations Moved to topic 2
Use of the convergence limit to calculate the ionization energy Allows a quantitative approach to this topic
Topic 13: The periodic table—the transition metals
Time: 4 hours (previously 4 hours)
Addition Deletion Rationale
More understanding of transition metals required, for example, magnetic properties Greater importance of transition metals in modern chemistry
Coloured complexes added as a sub-topic Greater detail than in the current guide with more emphasis on understanding
Trends in chlorides and oxides of the third period Reduces the amount of recall required
Specific examples of catalytic action and industrial processes Reduces the amount of recall required
Topic 14: Chemical bonding and structure
Time: 7 hours (previously 5 hours)
Addition Deletion Rationale
The concept of formal charge This is a more modern approach that allows identification of preferred Lewis structure
Mechanism and catalysis of ozone depletion Environmental application
Specific examples of catalytic action and industrial processes Reduces the amount of recall required
Topic 15: Energetics/thermochemistry
Time: 7 hours (previously 8 hours)
Addition Deletion Rationale
Standard enthalpy of reaction Moved to SL
Enthalpy of hydration Enables students to carry out lab work on energy cycles. Provides better coherence with Hess’s law in the core syllabus
Theoretical lattice enthalpies and polarizing effects The approach was too simplistic
Relation of ΔG to position of equilibrium Enhances understanding and links to topic 17
Topic 16: Chemical kinetics
Time: 6 hours (previously 6 hours)
Addition Deletion Rationale
A more thorough understanding of the use of the Arrhenius equation is specified Gives greater clarity to the syllabus
Topic 17: Equilibrium
Time: 4 hours (previously 4 hours)
Addition Deletion Rationale
ΔG = –RTlnK Application/connection with topic 15; note that solving quadratic equations for equilibrium expressions remains beyond the scope of this syllabus
Liquid–vapour equilibrium Reduces the amount of recall required
Topic 18: Acids and bases
Time: 10 hours (previously 10 hours)
Addition Deletion Rationale
Lewis Theory of acids and bases Moved from topic 8 (core)
Buffer calculation Moved to biochemistry option
Acidity of transition metal salts Reduces the amount of recall required; explanation of equivalence points on titration curves is still expected
Topic 19: Redox processes
Time: 6 hours (previously 5 hours)
Addition Deletion Rationale
EMF (cell potential) definition Provides greater understanding of the essential idea
ΔG = –nFE Connection to topics 15 and 17
No significant deletions as the topic contains key chemical ideas that are applied elsewhere in the course Concepts remain the same but some of the rote memorization has been deleted
Topic 20: Organic chemistry
Time: 12 hours (previously 10 hours)
Addition Deletion Rationale
SN1 and SN2 mechanisms Moved from core: more applicable to AHL
Electrophilic substitution—nitration Links to inclusion of Benzene in topic 10; provides more opportunities for applications and synthetic routes
Reduction reactions—carbonyls Provides more opportunities for applications and synthetic routes
Stereoisomerism in more detail, including E/Z nomenclature and diasteromers Updating of idea to align with the International Union of Pure and Applied Chemistry (IUPAC) and allow identification of isomerism in a broader range of compounds
Synthetic pathways introduced as a sub topic ; paths with up to four steps are specified, as well as the concept of retro-synthesis Previously only two steps were assessed which provided limited scope for application; retro synthesis gives an alternative problem-solving approach
Elimination A less useful reaction; removed to reduce the amount of recall
Condensation Naming of esters moved to topic 10
Condensation polymerization now in options A and B
Topic 21: Measurement and analysis
Time: 2 hours (new topic)
Addition Deletion Rationale
Nuclear magnetic resonance (NMR)—specifically interpretation of multiplets and use of TMS Moved from analytical chemistry option
Awareness of X-ray crystallography Prevents focus on a single technique in the process of structure elucidation

Options

The four option topics are new and so a comparison with previous option topics is not feasible. Each topic contains elements of quantitative chemistry, analytical techniques, environmental issues and organic chemistry, and there is new content in all of them to ensure the topics are up to date. Teachers are encouraged to look at each of the topics and decide which ones will best match the needs and interests of their classes.

Changes to external assessment

There are some changes to the examination papers. These are summarized below.

  • The weighting of the assessment objectives for paper 1 has changed so that 50% of the paper will address objective 3.
  • Assessment of the NOS may be incorporated into any of the questions in the three examination papers.
  • In paper 2 there will no longer be any choice of question. Students will answer all questions in section A (short answer) and all questions in section B (extended response).
  • On paper 3 there will be two sections: in section A students will answer data-based questions and in section B they will choose one of the options.