How I teach Infrared Spectroscopy

You can find here a folder of material I use to introduce IR spectra interpretation in a 70 min mixed SL/HL class.  It is tactically hyper-efficient but structurally sub-optimal: splitting this into two or three sessions of shorter duration could possibly be better.  But, hey, I teach a 240 hr syllabus in 150 hours; I can have my kids for an extra year and we would still not make 240!

Sequence-wise, I teach 10 (organic chem) -> Index of Hydrogen Deficiency -> IR -> 20 -> NMR.  I find IHD a generally useful tool that complements structure determination.

In this intro class, I first set the context with general idea of spectroscopy (5 min).  My hook is usually, “let’s say the shady dude at the corner tells you ‘it’s the good stuff’ – maybe you don’t trust him, but how would you know?  What…” [pause] “…Way of Knowing do you have?” [groans]

For the spectroscopy intro I use my diagram on absorption spectroscopy on wikipedia, which have just all the needed graphics and no extra:

(I never cease to be marvel at how the 2010-2011 drawings stand the test of time.)  While we are here, I point out how weird IR spectra are:

  1. wavenumber as unit
  2. non-uniform horizontal scale
  3. baseline on the top (signals go down)

…and promise them that in just 25 minutes they will be able to “look at the squiggles and identify a structure”.

I preliminarily introduce the students to the idea of band <=> FG correlation using the data booklet (table 26), without making use of it.  Before moving on, I activate their prior knowledge with a brief review of functional groups (identification / drawing molecules on the slate).  The review takes 10 min, and I make sure we hit the frequently confused pairs (amine / amide; ether / ester).  Since we do Opt D Medicinal Chem, I usually pull in MDMA, aspirin, fentanyl, and such.

I then hand out the 3-hydroxyproprionitrile spectra, and point out how difficult it is to actually use the table to make sense of the spectra.   IR tables are misleading because students don’t expect there to be false positives, and Type I errors are there all the time — especially in the low wavenumber / top-of-table area.  They also don’t actually show the shapes: it is not enough to know that secondary amines and alcohols are both “strong” in 3200-3400 cm-1, but you need to pick up the shape of the bands.

To counter the seriously unhappy looks, I hand out the comics. (With thanks to Vitor Ribeiro (Brazil), Robert Herzog (Germany), and Henry Hughes (Argentina), in the folder you have four languages to choose from!)   I give the students three minutes to read through it.  Most students only need 2:00 – 2:15, and they would themselves try to use the comic to interpret the proprionitrile spectra.

When the timer’s up, we meet as a class, and use the comic to work through the proprionitrile spectra (15 min, pairs / triplets):

  1. -OH “tongue”,
  2. no C=O,
  3. triple bond (CN or CC),
  4. draw the two possible proposals,
  5. eliminate alkyne (no primary amine)

I facilitate; most of the time students do most of the work.  (In a 60 min class I usually help in step 4: this is unnecessary if they have a few more minutes.)  In this segment, I just stand holding a print, and point and ask about the implication of applying each row.  (Pro-tip: there are four rows of interpretations, each associated with a color.  To refer to the >3000 cm-1 stretches, I look at the back of the print, trace my finger horizontally from the red until it rests in a box, then ask what the “red” row says about their proprionitrile spectra.)

Phew.  Time to remind them of prior promise kept: they did went “from squiggles to molecule”.  It’s super satisfying: all of them know they can now do something that looked impossible 20 minutes ago.  For this moment IR is one of my favorite classes to teach.

For practice, the students work in groups of 3-4, each with a copy of the “IR shuffling” stack and a pair of scissors. The students are asked to cut the molecules out, spread out all the spectra, and match them with each spectra, talking out loud their reasoning.  (Emphasize spreading out the spectra and the molecules: it’s essential in this activity to be able to compare and contrast.)  I work the room giving hints as needed.  Students can usually get to all-but-4 molecules in 25 minutes, or all-but-6 in 20 minutes. (Solutions are provided in the folder for your use as well.)  Somewhere along the line I let them know that the comic is in fact too advanced for them; that they do not need to memorize the exact location of the C=O bands, nor the final row of details.

Interpreting IR is then reinforced in subsequent classes, but I find that most of the kids can pick up most of it in one session.  The tongue, vampires, and beard just can’t be unseen.

January update for TRE

The following material has been added to the Teacher Resource Exchange folder:

  • Tests by JC
  • IR teaching materialsby JC
  • worksheet / activities uploaded by B-CJ and PB

I was transferring material from the myIB TRE group, but progress is stalled while I await responses on copyright / link issues (see discussion here).

Details

Tests

These are 9 tests I wrote in 2017.  All tests have 40 points, the same expectation as the IB papers of 1.5 pts / min. The recent papers are set in the sans serif fonts (as with the new IB papers) and uses the same boxes c/ dotted lines (as with IB papers). [The only formatting anomaly is in an answerline for calculation questions… I prefer not looking for the answer unless necessary.]  There are some data-based questions hiding here and there; most of the time I did the experiments but sometimes they are simulated (in Yenka). Empirically these tests aligned well with the percentages in the IB. A cohort of students with an average of 5.5 scores 65±2% in the tests.

Unfortunately I wrote by hand (pretty color pens and all) the solutions / walkthrough, and I didn’t scan most of them. With the exception of two papers you would have to supply your own answer key.

I no longer teach topic-by-topic, so the sequential unit tests are probably some of the last ones I write. The new tests are mostly very broad across topics, which makes them not very useful for any other teachers. Pedagogically this works better for me, but, sorry.

You can find them both under By Resource / Tests, as well as topic XX / tests.

IR teaching material

For usage and details please see the “How I teach IR” post.  You can find these under By Resources / problems-practices / Jon C / IR, and by Topic / 11/21 / problems-practices.

2018 May IB chemistry practice schedule

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I created a “past paper practice schedule” to help my Y2 students to prepare steadily for their upcoming exam, and you can find that here.

HL Past paper practice schedule (2018)

There is a separate one for HL and SL students, both meant to be printed on a portrait A3 sheet (and posted on their study space).  My proposal is for them (or your students) to do at least the top paper properly.  By “properly” I mean specifically:

  • timing themselves, preferably on each question, but at least for the time it takes to do the entire paper;
  • marking their level of certainty for each response, so they are aware if they have gotten a question right just because they were lucky, or if they thought they understood something but didn’t;
  • score their answers, so they can
  • reflectively analysing their mistake. This is the key to the whole exercise: practice without reflection makes permanent and not perfect.

To do this properly would take 2-3 times the amount of time just doing the past paper would take (e.g., to allocate 2 hrs for a SL P1, or 4-5 hrs for HL paper 2; allocate time accordingly).  If they have more time, or targets more rapid improvement, they can additionally do the second paper.  The admonishment is that if they must choose between doing one well or doing two poorly, always choose to do less but better.

My selection of papers is based on my teaching progress (we have largely finished with all the SL material by now, but would not be done with HL until Feb).   Unfortunately this is drawn in Illustrator and not easily editable.  To correct for the discrepancy between 2009-2016 syllabus, I have also provided my students with a syllabus comparison (this is tidied up from the TSM)


The IB grade boundaries are very wide.  For the most part, near the conclusion of their two years, improvements will be steady but slow.  They are unlikely to see immediate improvement from week to week. To that end, I have also prepared a score-charting sheet for them to monitor their progress (A4).

The vertical blue boxes help divide the weeks, but they should be marking their % on the solid line emitting from the date.  The horizontal brown boxes shows the rough grade boundaries for Paper 2. (That for P1 is usually ~10% higher, and I invite my students to use blue pen to mark their P1, red pen to mark their P2, and green for P3 — same color code as in the practice schedule.)

IB teachers: If you subscribe to the Google Drive Teacher Resources Exchange, all of this would already be synchronized to your hard-disk under /by topic/General: cross-topic/study skills.  If you wish to subscribe, instructions can be found on the myIB DP chemistry forums.
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Codenames (game) for organic chemistry

Vlaada Chvátil‘s Codenames is a great party game for 4-8 players.  Players are divided into two teams in front of a 5 x 5 grid of words.  Each team has a “spymaster”, seated across the table, who knows which words belong to the team.

Fig 1. codenames gameplay

The teams take turns to identify all the cards belonging to their team.  They do this using only one-word clues from the spymaster.  The first game takes 20 minutes; subsequent games finishes in fifteen.

The game relies on players seeing the relationships between words.  I thought the idea would work great with chemistry as well, and tried it out with my students in a pre-Christmas class using a handwritten set of organic chem vocabulary.  It worked well — when the spymasters know their chemistry!

I tidied this up in Illustrator, and the PDF is available here: chemistry codenames PDF.  This is designed for printing to A3 size.  In the PDF you can find:

The team cards (anilinium and carboxylates):

Fig 2. Team cards – the PDF has 9 yellows, 8 purple, and 7 grays.

(These games must start with the yellow carboxylate teams.)

Scenario cards

Fig 3. Twenty scenario cards – these work with the 9-8 distribution, with one extra yellow for starting first.

Chemistry “words”

Fig 4. Organic chemistry codename words – the inverted gray words for the spymasters.
Fig 5. Organic chemistry structures.

This works with my students who will be working on the Drugs option of IB chemistry.  There is also a set of blank cards for you to write / draw your own setup.

[box type=”bio”] Customizations: If you have a Silhouette you can use the guides to directly cut out some cardboard backing, using the Cards layer.    There is an Adobe Illustrator action embedded in the PDF, called codenames that automatically generate the inverted version.  It does so by creating a copy of the selection, rotating it 180, scales, and lowers the opacity.[/box]

If you enjoy the game, please support the original creator – both Codenames and Codename Pictures are quick good fun with friends and family.

The secret area in acid-base titration

With phenolphthalein (in 50% EtOH) as the indicator, and base as the titrant, it is common knowledge that the solution turns from colorless to magenta.  However, with careful sub-drop addition, the solution actually first turns milky-white, then milky-pink, before it clears up to a transparent pink at the end point:

This is a titration of 1.00 M nitric acid with 1.00 M NaOH, with phenolphthalein (50% EtOH) as indicator.  The center and right-most titration was performed by Philip L.

After learning about the existence of the “secret area”, many students did the titration with utmost care.  It was fun (and pretty tense) to watch.

Chemistry-wise I am not too sure what is precipitating.  (Both the acid / base forms of phenolphthalein should be completely soluble.)  Surely I am not the first to notice the transition, but I have not seen this described in the literature.  If you have any leads please do let me know.

Van der Waal Equation / Ideal Gas Law Explorer

See the Pen Vue / graph.js – VdW eqn exploration by Jon Chui (@jkwchui) on CodePen.

The ideal gas equation PV = nRT assumes an ideal gas of which the individual gas molecule

  1. has no attraction for another gas molecule,
  2. occupies no volume of its own.

Real gases do not obey the Ideal Gas Law at some conditions, and their deviation can be corrected by using the Van der Waal equation instead.  In the VdW equation, an attraction constant a and a volume constant b is introduced to account for the two above properties of real gases.

A curious and diligent student revised over summer and asked about the VdW equation.  I tried to answer Matthew’s queries to the best of my ability (which isn’t much.  Sadly, after years with Tom Fyles I haven’t developed the taste or acumen for physical chemistry).  While doing so, I realized that a list of measured VdW constants is easy to find, but visualizing how this correction impacts the P-V isotherm is not available.  So I built one.

I used Vue.js for the two-way binding and reactivity, bulma for styling, and chart.js for graphing.  Panning and zooming used the Pan/Zoom plugin for chart.js.  I tried plotly.js for graphing but I could not get the reactivity to work.  Actually, I still don’t understand many aspects of the reactivity: somehow if the display of the array at the bottom is removed from the html, the logic in the javascript (specifically, computed properties) fails.  If you know why, or a better way to go about this, please enlighten me.

There are two chemistry aspects that I appreciated from the explorer.  First is how well the ideal gas law work: the red and gray curves coalesce almost perfectly.  As an IB chemistry teacher, every year some student wants to measure the VdW constant for their Internal Assessment.  Some inevitably think I am mean for rejecting their proposal (how do you know that I can’t do this?) — I think the visual would do wonder to convince them of the difficulty of what they propose to do.

Second is about the existence of the “oscillation”, which I have never thought about.  To see that for yourself you can choose a = 300, b = 0.1, and slide the temperature up from about 70 to 90.  This, of course, goes back to point out how I gravitate to the statistical rather than the analytical; the square term in V should have revealed that this cannot be monotonic.

Building this has been a fruitful learning experience for me, and I can see this framework being useful elsewhere.  I will next be looking to re-factor this out into a Vue component.

Paper 2 Analytics: first explorations

I’m a connoisseur for chemistry exams.  (I need a life!)  Writing good exam is an art, where the final paper need to represent an optimal blend of objectives (skills required), topic distribution, chemical theme, and algorithmic complexity, all within a constraint of points.  It’s quite sad that this intricacy is invisible to most.

IB chemistry paper 2 is distinctive in that while the format is preserved over the past 20 years — 135 minutes, 90 marks; 40 marks compulsory, 25×2 marks optional — there is a subtle evolution within the questions themselves, with the later years reading more beautiful to my eyes.  I think I see a trend of more even topic coverage, enhanced connection between topics, and deeper links with the practical side of doing chemistry.  This is manifested on both the scale of individual questions as well as over the whole paper.

A hunch does not science make, and I started doing some analytics to better understand what it is that my “sense of beauty” is telling me.  The first take is to emulate the IB Questionbanks: simply take an exam and categorize each question as a topic (e.g., 9 – redox) — points (e.g., 12 pts for Q1) pair.  Doing this for May 2000 / 2006 / 2009 / 2013 shows that it “works”, but not at a fine enough granularity; it is much better to tackle this on a sub-topic (e.g., 20.4, elimination) and sub-question (1a-iii) scale.

Doing this on a spreadsheet, using some primitive conditional formatting and summation, can show the big pattern: an example for the May 2000 paper 2 is shown here.  (The original spreadsheet.)

Visualizing May 2000 paper 2.
Visualizing May 2000 paper 2.  (Incomplete; the entire paper would span another page.)

Procedurally I first (A) established the sub-topics (color-coded for HL/SL material) and (B) questions and their splitting.  For each sub-part I would (C) enter its point value, and (D) locate the relevant sub-topics (referencing their point values from part C).

These can then be (E) automatically tallied up, and conditional formatting to visualize the representation of the topics.

The advantage of this is its technical simplicity; entering new papers is a simple matter, and the results is immediately visible.  I’ll be referring to this as the Instant Gratification method.

Having thought about this some more, however, this instant gratification is ultimately a waste of time.  A much more upwind option is to systematically tag each sub-question for:

  • points
  • objective (skill requested: e.g., “define”, “calculate”, etc)
  • theme (e.g., organic, environmental)
  • sub-sub-topic (e.g., 4.2.1) in the 2009-15 syllabus, with point value [4.2.1, 3]
  • examiners notes
  • JC comments

All of the question from all years is placed in a single array, and subsequently visualized.  The time required to enter the data is marginally higher than the IG method, and the results would need to be visualized programmatically.  The benefit of having all this data is that it would be possible to skin the cat in more than one way.

Adding to the value of the more rigorous approach is the impending switch to a the 2016-22 syllabus.  The new syllabus have entirely different topic number from previous syllabi, and would render the 1st/2nd edition IB questionbanks obsolete (the mapping is incomplete and inconsistent).  This indexing / analytics effort would thus double as the foundation of a complete questionbank that goes back 20 years.  Having this database at hand is extra-spiffy when coupled to the “chemical dependency” project I’ve been chipping away (more in a later post); it would also open the possibility for student analytics, wherein after attempts an automated report can be generated to pinpoint their strengths and deficiencies.

So at the moment I’m slowly plugging away there, mildly burdened with anxiety that my first pass does not captured all that is needed.  A complete pass of a paper 2 takes 2-3 hours, and it takes mental work but not to a prohibitive extent.  Going back to 2000 would take ~80 hours in total, with an additional 6 hours each subsequent year for maintenance.  Visualization of those data will be the subject of the next post.

IB chem 2016-22: topic changes

This is a 3-part commentary on the new syllabus, which begins examination in May 2016, and is thus relevant to the first years coming in Sept 2014.  These are meant for IB chemistry teachers, and especially for those who have taught the 2009 syllabus.  The first part speaks about the philosophical differences, the second (this part) is a topic-by-topic comparison, and the last part talks about the changes in Internal Assessments.  All opinions are entirely mine, and I am not affiliated with IBO.  As a personal project with no editorial help, there is bound to be errors and omissions; your comments would be most welcomed.

Overall structure

The overall structure of the syllabus is preserved but with varied proportions.

2009/2016 guides time allocation
2009/2016 guides time allocation
  • The lab component stays the same, with Group 4 project intact.  However, there is now a list of prescribed experiments (examined in paper 3).  The internal assessment undergoes a historical change-over, from a portfolio of experiments to a 10-hour IA — in-line with other groups — using new criteria.  This will be examined in more detail in the next post.
  • The options are reduced from “7-choose-2” to “4-choose-1”, with overall hours reduced from 45 to 25.
  • Core and HL material now incorporate material from the removed options.  Most obvious is the inclusion of spectroscopic techniques, but environmental and organic also saw themselves into the core/HL material as well.

I am very happy about the addition of spectroscopy as a mandatory topic.  Spectroscopy is bedrock to modern chemistry, but it is neither something that students are able or willing to learn on their own.  In the past I have made analytical chemistry a compulsory option, but students would privately opt out: now we assert that this is important and they all need to know it.

Topic Formatting

While the 2009-2015 syllabus topics comprised solely of assessment statements, the 2016 syllabus is much richer in content but omits the assessment statements.  This omission was intentional, as examiners feel that the presence of assessment statements restricts the question they can pose in exams.  The content of each topic is instead split into sections such as “understanding”, “skills”, “applications”, “theory of knowledge”, and “cross-curriculum links”.  I love this decision.  The assessment statements encourages a piece-meal, insulated “study for exam” mindset, whereas the current approach is both richer and more holistic.

What is missing from the guide, however, are the hours recommendations.  The 2009-guide recommend teaching hours by the sub-topic, for example, 1 hour for the reactions of organic alcohols.  The 2016-guide, on the other hand, simply gives the teaching hour by a topic: there would simply be a recommendation of 11 hours for “organic chemistry”.

For teachers new to the IB, the new syllabus, broad and holistic as it is, would be much harder to start teaching with.  However, since there is substantial parallel between the 2009 and 2016 guides, I would recommend planning lessons with both guides on the first go-around, since the assessment statements provide concrete tasks that your students need to be able to do; they would also be able to look at the old sub-topic hour recommendations and extrapolate to the new syllabus.  You can consult the map in the next section to find the mapping.

Topic changes

While there are limited changes to the material included — chemistry is a mature discipline — the topics are often numbered differently.  There is a general push in combining multiple sub-topics into a new one; for example, what used to be “3.2 physical properties in periodic table” and “3.3 chemical properties in the periodic table” is now simply “3.2 periodic trends”.  Sometimes this gives better clarity to the syllabus, but sometimes I feel it overshot (for example, both core kinetics and equilibrium have exactly one sub-topic, which is no help at all when it comes to teachers structuring their year plan).

Sitting down with both guides side-by-side, I charted the mapping of each topic, and annotated the addition and removal of material.  I then cross-referenced this against the list by David Allen.  This post will get elaborated on as I gain a fuller understanding of the new syllabus.  You can download a printable copy (designed to print on an A3 page) as a PDF here.

Full 2009-2016 syllabus topic comparison
Full 2009-2016 syllabus topic comparison.  (Click on the image for a full size viewing)

Each topic sits in its own box, with a horizontal line demarcating where the HL material begins.  On the left are the topic numbers / titles from the 2009 guide (over a blue background ); on the left are the topic numbers / titles from the 2016 guide (over a green background).  The numbers next to the the units, with a pink background, are the hours.  These hours are extracted for the old guide, and extrapolated by me to the new sub-topics after mapping each units.  (That is, the hours for the new sub-topics are not official.)

Blue arrows show mapping of a 2009 sub-topic to a 2016 sub-topic, at the same level (e.g., HL->HL).  Red arrows indicate where a previously HL topic is relocated to a SL topic, whereas green arrows denote a SL -> HL transfer.  Dashed lines show partial mapping.

Important notes on the new sub-topics are given in red font under each title:

Let’s look at the changes in each topic one at a time, in bullet-points, followed by my comments in square brackets.

1: Stoichiometric relationship

IB-chem-2009-2016-syllabus-comparison-03

  • The topic is renamed from quantitative chemistry to stoichiometric relationships.  [I think this is just cosmetic.]
  • A sub-topic of the 1.1 particulate nature of matter is added.  [This makes explicit something that we all taught, or expect students to know as prior background.  I like this, especially the mentioning of mixed states of matter.]
  • Within the concepts in 1.1 some are newly explicit, including the distinction between homogenous and heterogenous phases.
  • Within 1.1 is a mentioning of atom economy.  [While links in stoichiometry right away to environmental concerns, I suspect that this will have to be tackled after finished with the rest of stoichiometry.  It certainly would take a fair bit of time to grasp.]
  • Mole concept is mapped directly, with a special emphasis of ozone pointed out as an application.
  • the rest of stoichiometry is simply smushed into one sub-topic.
  • An associated change with the gas laws is hidden in the revised data booklet: what used to be incorrectly called STP is correctly referred to as SATP (Standard Ambient Temperature and Pressure).  This is a much welcomed correction, and would prevent student confusions about the different “standard” encountered in gas laws and thermodynamics.

2: Atomic structure

IB-chem-2009-2016-syllabus-comparison-04

  • Concepts regarding the nucleus is condensed into a single section 2.1.  This includes mass spectra.
  • While mass spectra is included, the instrumentation is not; no more vaporization-ionization-etc.  I like this cut: sector mass spectrometers declined in importance since the 90’s, and is now eclipsed by time-of-flight / quadrupole instruments.  (If I were designing the curriculum, I’d probably introduce ESI-ToF as a principle for how mass spec work: it’s intuitive and relevant.)
  • Electron arrangement (i.e., “2.8.2”) is entirely out, replaced by uniformly using only electron configuration (i.e., [He]2s1) in both SL and HL.  This change is needed to buttress some other changes in the syllabus (in bonding, then with aromatic compounds), and would remove the confusion of notation for HL students.
  • Trends in ionization energy and conversion between energy and frequency of light is relocated as a HL-only section 12.1.

3: Periodicity

IB-chem-2009-2016-syllabus-comparison-05

  • Physical and chemical properties, previous separated into different sections, is condensed into one 3.2 periodic trends.
  • Within 3.2 are properties of row 3 oxides, previously a portion of HL topic (13.1)
  • The other half of ex-13.1, the row 3 chlorides, are removed entirely.
  • Note that Allen’s post, he comments that “similarities and differences between elements in the same group” is out; this contradicts the guide in that a key understanding is “vertical and horizontal trends in the periodic table”.
  • The first-row d-block elements have been officially expanded into two topics, 13.1 & 13.2.  In 13.2 is the formal treatment of colored complex and their origins; this is implicit in the 2009 syllabus, and covered in Brown & Ford.
  • Transition elements is now redefined to include scandium (Sc).

4: Structure and bonding

IB-chem-2009-2016-syllabus-comparison-06

  • For structure and bonding, the major change is distributing physical properties (ex-4.5) into each bonding topic.
  • There is no removal of content, only addition.
  • Covalent bonding used to be a behemoth topic, and is now broken into the nature of bonding (4.2) and structures (4.3).
  • 4.3, covalent structures, now include resonance structures, previously an HL topic.  This was previously prepared by including electron configuration as part of topic 3, and path the way for aromatic structures in organic.
  • The family of carbon allotropes is expanded to include graphene.  This keeps up with the times, even though I would have add carbon nanotube and expand on this as a discourse of topology…
  • HL section 14.1 is a grab-bag of concepts, several aspects being put together from previous 14.1/2.  The most note-worthy addition is the assignment of formal charges.
  • I am unhappy about the inclusion of the obviously wrong statement “strength of dispersion forces < dipole-dipole forces < hydrogen bonds” in the syllabus.
  • Some clarification of terminology:
  1. instantaneous induced dipole-induced dipole is explicitly referred to as London forces (synonymous with dispersion forces), and
  2. Van de Waal’s forces is redefined as all of London (induced dipoleinduced dipole), Debye (permanent dipoleinduced dipole), and Keesom forces (permanent dipolepermanent dipole).
  3. Coordinate bonds exclusively used in place of dative bond
  4. Electron domains now used in place of negative charge centers.
  • If you have been looking at the graphics, you would have noticed the addition of ozone as an application here.  Someone really like ozone… in this section, the role of CFC is especially highlighted.

5: Energetics

IB-chem-2009-2016-syllabus-comparison-07

  • There is rearrangements but no major changes in the SL syllabus.
  • As with many other topics, there are now explicit applications specified… and as with many other topics, it’s ozone that is specified.  I am personally ambivalent about so much emphasis on ozone.  On one hand it’s a a nice story linking chemistry and society — where for once humanity did the right thing — on the other hand the chemistry of ozone in the stratosphere is far more complex than can be understood at the IB level.
  • Drugs is explicitly specified as an application as well.  I am very tempted to include a ligand-receptor simulation as an investigation.
  • HL topic 15.1 is a combination of what used to be 15.1 and 15.2.
  • In addition, however, 15.1 also adds solvation to the variety of standard enthalpies.  I think this is a wonderful addition and supports a more accurate view of what “dissolve” means.
  • Even though 15.2 is a mere consolidation of entropy and spontaneity, with no addition of material, it would probably need to be taught differently.  In the 2009-syllabus, Gibbs free energy is treated as an afterthought, a dead end that leads nowhere.  In the 2016-syllabus ΔG is back in its rightful place, central to physical chemistry: there is now link to equilibrium (ΔG = -RT lnK) and electrode potentials (ΔG = -nFE), so students would need a better grasp of the concept than before.

6: Chemical kinetics

IB-chem-2009-2016-syllabus-comparison-08

  • My reading of the syllabus is that there is nothing added or taken away, in both HL and SL syllabus.  This confuses me because there is 2 extra hours allocated to the SL syllabus.  (Allen mentioned that potential energy profiles are added, but I think that it has always been in.)
  • I wish the integrated rate laws would be back in, but I think it’s wishful thinking considering the general deterioration of mathematical / arithmetic prowess.  Without integrated rate laws, there is absolutely no reason to acquire a time-series in practical investigations — but the IB ask questions about time-series anyway.

7: Equilibrium

IB-chem-2009-2016-syllabus-comparison-09

  • Woohoo!  Reaction quotient Q is in!  The existing way of dealing with changes in equilibrium was making predictions with La Chatelier’s principle, which is fine in a general hand-waving way but falls apart in numerous occasions.
  • Liquid-vapor equilibrium is explicitly removed.  Since it is just an extension of intermolecular forces / enthalpy of vaporization, however, I am not sure if it is entirely removed.
  • In 17.1, the equilibrium law (previously 17.2) now includes the relationship between ΔG with equilibrium constant K.  I love this change — it nudges students to a coherent, holistic view of thermodynamics, kinetics, and equilibrium.

8: Acids and bases

IB-chem-2009-2016-syllabus-comparison-10

  • Lewis acids and bases are moved from SL to an HL section (18.1).
  • Salt hydrolysis (ex-18.3) is removed from the syllabus entirely.
  • Allen mentioned that buffers are removed; my reading of the guide is that it’s moved to topic 18.3.
  • Titrations, indicators, and graphical representations are consolidated into 18.3
  • The term pH curves will replace titration curves.
  • pOH is removed from SL (?), and temperature dependence of Kw is now an HL-only topic (in 18.2)
  • New is 8.5, acid deposition.  This used to be in Opt E, Environmental chemistry; the entire option is broken down and rolled into the core syllabus.
  • Amphiprotic and amphoteric species are explicitly defined in this unit (previously spread over ex-13.1 and 8).

9: Redox processes

IB-chem-2009-2016-syllabus-comparison-11

  • No content is removed from either SL or HL syllabus.
  • The general clumping of topic happens again here; 9.1 contains all the foundation of redox (previously 9.1-9.3), and 9.2 contains both voltaic / electrolytic cells.
  • New to redox is the explicit inclusion of Winkler titration for the determination of dissolved oxygen.  This is another environmental connection.  (This is a specific example of a redox titration; presumably permanganate titration, having showed up in May 2013 paper 2, will also be included amongst other redox titrations.)
  • Fuel cells is included as one of the applications for redox chemistry.  I think this used to be in the Technology / Chemical Industry option.
  • New to the HL syllabus is the connection between Gibbs free energy and standard electrode potential.  Since ΔG is previously connected up to K, students would now be able to see the connection between redox and equilibrium as well (and thus be able to make sense of the equilibrium signs in the standard electrode potential data tables).
  • For HL there is an explicit mentioning of electrochemical cells in series.  I don’t feel strongly about its inclusion, one way or another.  Often questions on this just become another disconnected intellectual exercise

10: Organic chemistry

IB-chem-2009-2016-syllabus-comparison-12

  • There is major rearrangement in this unit.  Topic 10/20 in the 2016-syllabus is an amalgam of what used to be 10/20/Opt G.  Together with the change in topic structuring, I am not very certain that I have picked out all the changes.
  • Nomenclature of nitrogen containing functional groups are out; that is, no nomenclature of amines, amides, or nitriles.  Nomenclature of alkynes are in, and nomenclature of esters are now in the core syllabus (previously HL-only).
  • Benzene is included in the core functional group chemistry; electrophilic substitution is in the HL syllabus (previously Opt G).
  • Reduction of carbonyls (e.g., with LiAlH4, NaBH4) are now in.  This is a nice complement to the staple oxidation of alcohols.
  • Markonikov (presumably also anti-Markonikov?) addition is now in.
  • SN1/SN2 is moved from SL to HL.
  • Elimination and condensation, according to Allen, is no longer in either SL/HL syllabus.
  • In stereoisomerism (prev 20.6, now 20.3), the E/Z nomenclature is introduced.  (But not R/S for optical isomers.)  The E/Z notation, together with the cis/trans notation, would displace the term “geometric isomerism”.
  • An understated change is the number of steps present in a synthetic route: it used to be 2, and is now 4 in the new syllabus.  This requires students to really have understood their organic transformations.

11: Measurements and data processing

IB-chem-2009-2016-syllabus-comparison-13

  • Here is the biggest change in this syllabus: spectroscopy is back in the core.  Wonderful!  The 2016-syllabus adds a section 11.3 to the core measurement topic, and includes the interpretation of mass spec, IR, and NMR.
  • These used to be in Opt A, but the emphasis here is on the interpretation of spectra and seemingly all mentioning of instrumentation is out (along with theory of IR spectroscopy).
  • Explicit in 11.3 is also the Index of Hydrogen Deficiency (IHD), which was an implicit skill in 2009-syllabus Opt A.
  • For SL, the treatment of NMR spectra is restricted to integration and chemical shift; HL students would also make use of multiplicity (but not coupling constants).
  • X-ray crystallography is also briefly introduced in the HL-extension 21.1.

The introduction of spectroscopy in the core would allow for more interesting spectroscopy questions, which is somewhat hamstrung when it was an option question (requiring a “fair” distribution with other option topics).

I haven’t thought through the options yet, though Opt B (biochemistry) looks largely similar to the current Opt B.

All in all, in terms of chemistry, the 2016-syllabus is deeper and tightly connects different topics, and would be instrumental in building better budding chemists.  It also provides substantial help in connecting with other subjects (and ToK).  I’m excited to teach it!

In the next part we look at the new internal assessment, completely overhauled, changes which I am far less enthusiastic about…

Edit 5 May 2014: updated with pointers to new terminology, from a list compiled by Catrin Brown.

Jmol chemical element swatches

Here is an RGB swatch palette for chemical elements, using the Jmol/JSmol convention as defined on its wiki page.  This is an ASE (Adobe Swatch Exchange) file and should be of use across the entire Creative Cloud suite (including Photoshop, Illustrator, and InDesign).  Download here [icon name=”icon-download”]; details, installations, and caveats follow.

Read moreJmol chemical element swatches

The BATCHEM project

Chemistry is the study of matter, and the bedrock upon which studies of medicine, materials, energy, and the environment lies.  As such, introductory chemistry is a required subject for all scientists, and a solid mastery of chemistry gives deeper insight and appreciation to many other matter.

It is a challenging subject to study, as the “central science” demands from its student unusual versatility.  Proficient chemists seamlessly transition between the symbolic, microscopic, and macroscopic worlds, intuiting — as the situation demands — \(1.02 \molar \ce{CaCl2_{(aq)}} \) as an abstraction (with numerical properties such as heat capacity, volume, and mass) and as an imaginary movie in which hydrated \(\ce{Ca^{2+}}\) and twice that amount of \(\ce{Cl^{-}}\) are screened by water molecules, tumbling, colliding, and exchanging waters.  These then informs the chemist what to do in the physical world he occupies, from the choice of temperature and glassware to the choice of simulation parameters.

A proficient chemist also needs to be acquainted with the breadth of what nature offers, and understand the human context in how we humans can understand and communicate this breadth.  There are lots of facts to learn, and lots of communication protocols to be familiar with.

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Proficiency is best achieved by deliberate practice.  Deliberate practice, in short, is practice that specifically targets what one is not able to do.  To use a sports analogy, a basketball player weak in his off-hand would spend much time working on dribbling drills using that off-hand, whereas another who has a poor shooting form would work on habituating a good shooting form by repeating the action, first in isolation, then in game-like pressure and context.

Few students engage in deliberate practice, and early on in teaching I attributed this to a matter of effort.  Deliberate practice, in its constant push against one’s comfort zone, is necessarily painful and saps the will.  But there is really two more obstacles than that.

First, we need to know our weaknesses before we can surmount it.   To profoundly improve, one must not only move known unknowns into the known known realm, but also reach and wrench the unknown unknowns into the known unknown world.  Some students are willing to endure the pain, if only they know how to invite the pain.

Second, we need to have a realistic approach to surmounting that weakness.  Students can know they are weak in an area, be willing to tackle the weakness, but simply not knowing how to do that fruitfully, or lack suitable tools for doing so.  While throwing yourself heroically at the cliff sometimes work, there’s less bruises going up the gentle slope on the other side — and you still get to the same place.  While the fruits of learning is a state function, the process of learning is decidedly a path function.

Thus deliberate practice demands, in addition to perseverance, a level of reflectiveness and foresight inaccessible to a beginner.  This is where the teacher comes in, an explorer who have been through the wilds and know the short-cuts.  They would ideally also have a full complement of maps, tools, and wiles to guide the tutees up the cliffs for which they just have to climb.

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Just as chemistry demands unusual versatility in its study, it also demands unusual versatility in its teaching.  A workman’s utility belt wasn’t enough to hold the necessary tools; I need Batman’s belt, and I didn’t have one.

Teaching at a school in which students come from 80+ countries, our students arrive with vastly different background. In the same class I have a student who medaled in International Olympiad, and a student who have never studied chemistry before.  The latter needed more attention, but also much more carefully gradated practice material, and I could not provide for her.

Designing and typesetting just right exercises and questions is unreasonably time-consuming in chemistry, to the tune of 10-20 min. per short answer question.  Beyond the personal shortcoming called “perfectionism” (thus endless revision), there are two additional complications here.

The first is that chemistry, reflecting the tortured and uncertain world around us, is intrinsically full of exceptions and corner cases (see: reduction potential of Li, boiling point of Hg, properties of water).  Setting questions properly means tracking down properties, to ensure that the practice really coheres with reality.

The second is that much of chemistry is visual.  Text and numbers are easy to write and typeset, but figures, diagrams, and graphs are how prospective chemists ought to think.  There’s a non-trivial overhead for producing figures and ensuring they work for the exercise.  Heck, even just typesetting \[ \ce{CH3CH2OH_{(l)} + x O2_{(g)} -> y CO2_{(g)} + z H2O_{(l)}} \DHc = -1370 kJ/mol \] in HTML can take five minutes.

In any case, the upshot is that once a student exhausts practice material in the form of text-book questions and past papers, he’s done, at least until he can forget the solution he’s seen.

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Wouldn’t it be nice to have an Infinite Tome of Just Suitable Chemistry Questions? Imagine such a tome with guided practice for each of the disparate skill-set that makes up chemistry, which push you harder when you’re comfortable and eases off when it’s too hard.  Imagine that it can talk you through perplexities in response to what you’ve done.  Beautifully and accurately illustrated, the illustrations even let you turn the nanotube to look through the ends.  And the illustrations can hop hop hop out of the page to another piece of paper (or into the projector light), while the original remains.

I think that’d be awesome, awesome like Batman’s utility belt, and I’m convinced that it is doable.  Since it’s “awesome like Batman’s utility belt”, I call it BATCHEM in my head.