Quest for a Stable BOO

Is BOO stable?

A student in my chemistry class would be scribbling away an answer to the question. Everyone else might be wondering: “What kind of a question is that?”

Happy Halloween! If you are looking for the perfect BOO pumpkin, I suggest visiting The Pumpkin Lady’s carving patterns. I particularly like the one shown below from that website.

If instead you’re interested in a strange trip down the rabbit hole, with geeky chemical structures, then read on!

Two weeks ago, my first semester general chemistry class went through Lewis structures in great detail. I tell students that the most important thing they will learn in my class this semester is how to draw good Lewis structures. While Lewis structures may not provide the most accurate picture of what electrons are doing in chemical bonds, they are the epitome of practicality and usefulness to all chemists.

Drawing Lewis structures can tell us something about the stability, or conversely reactivity, of a molecule. A Lewis structure can tell us the shape of a molecule and its polarity; both are useful things to know when designing a molecule for a specific application. (The pharmaceutical industry is the business of designing drugs.)

In my class, students learn four guidelines to evaluate if a Lewis structure represents a stable structure.

·      Atoms try to reach an octet (especially C, N, O, F). While B can go below, and larger atoms can go above, the closer they get to the octet, the better. This is known as the octet rule, but it’s really a rule-of-thumb.

·      Small formal charges (+1 or -1) assigned to an atom are okay. Try to avoid large formal charges (+2, -2 or larger in magnitude).

·      If there are formal charges, try to have the -1 on the more electronegative atom and the +1 on the less electronegative atom.

·      The existence of equivalent resonance structures is stabilizing (a la Heisenberg).

Let’s apply these to the original question: Is BOO stable?

The first structure a student is likely to draw is shown below. I christen it Bent BOO.

While the oxygens have octets, boron goes severely below (with 5 rather than 8 in the “octet count”) and the unpaired electron on B makes the molecule more reactive. Also, there is a formal positive charge on an electronegative O, and the O–O peroxo-bond is also prone to react chemically.

We could potentially improve things with Triangle BOO. Oxygens still follow the octet rule. The problems on B remain, but we’ve eliminated the positive formal charge on O.

However, my students have learned that the triangular O₃ structure of ozone suffers from ring strain due to Valence Shell Electron Pair Repulsion theory (the Pauli Principle again at work!). Oxygens with four electron clouds prefer to have 109.5-degree bond angles, and not 60 degrees in the triangle. Repulsion breaks open the ring.

The next structure one might draw is Linear BOO. There is an improvement for B (which is 6 by the octet count). Most general chemistry textbooks will declare that boron typically goes under the octet rule and has 6 in the count. One of the oxygens is a little worse having gone down to 7 from the octet. But having an equivalent resonance structure helps. And there isn’t the problem of the positive formal charge on oxygen.

Perhaps we should call this OBO, but since it’s Halloween we’ll stick to BOO. Also, chemists often write the carboxylate group as COO-minus even though C is in the centre, so BOO seems reasonable. My students worked on a problem set two weeks ago themed with nitrogen oxides as the theme. They had to draw structures such as NO₂ and explain why it was reactive (i.e. less stable) and they found that Lewis structures with N in the centre are superior to N at one end. Students then drew the more stable nitrite anion (NO₂ with a -1 charge overall). By adding a single electron to NO₂, they could draw good Lewis structures that followed the four guidelines.

Hence, they might probably guess that a more stable BOO might exist as an anion. By adding an electron to the non-octet oxygen, you get Linear BOO Minus consisting of a pair of resonance structures.

This is better than Bent BOO Minus where B is down to 4 in the octet count, rather than 6 in the linear version.

But maybe there’s another way to avoid reactive unpaired electrons. Bring two molecules of BOO together!

Possibly the best structure might be Two-Square Double BOO. Oxygens follow the octet rule. Boron has its typical 6 in the octet count.

But squares with 90-degree bond angles are still strained rings, although they are not as strained as the triangles. The two-square structure might open up to a six-membered ring, Hex Double BOO.

The two radicals on B might still be spin-paired (dashed double-headed arrow) and Double BOO might be a fluxional molecule. The preceding sentence is not something my general chemistry students would write, but a student who took my physical chemistry class would have learned about spin-paired singlets/triplets and possibly fluxional molecules (time-permitting).

Could you do better with anions of Double Boo? That strategy worked well for single BOO.

Adding two electrons to the hexagonal structure gives us Hex Double BOO Minus. (Note this is a -2 anion.) There are no unpaired electrons. B is 6 in the octet count and all oxygens follow the octet rule. However, the negative formal charges are on the less electronegative B.

Also the structure looks ugly and it has the more reactive peroxo bonds. What about Star Double BOO Minus? It’s an aesthetically pleasing and creative structure!

While it might look beautiful, ring strain is likely to open up the bridgehead oxygens leading to the symmetric Square Double BOO Minus. It’s a decent structure and the two negative formal charges are kept as far apart as possible to reduce repulsion. However, it still has a strained square.

What else can we do? Can we triple BOO?

I proudly present to you today’s winner: Hex Triple BOO Minus. (Note it is a -3 anion.)

It has a boroxine (B₃O₃) core, a stable motif found in a number of chemical structures. It’s even possible to have all atoms obey the octet rule in the resonance structure on the right. While that structure has the formal negative charge on the less electronegative boron, this is also found on stable anions such as BF₄ with a -1 charge.

Compared to all previous structures, Hex Triple BOO Minus actually looks pretty good. Triple Hex BOO as a moniker would be more Halloween-like, but since the name tells us something about the structure, it really is a Hexagonal Triple BOO.

But is it really stable?

Hopefully if I posed this question my students would ask “stable with reference to what?” Good question. They’ll have to wait until next semester when we talk about thermodynamics! In the meantime, any of those unstable structures is likely to behave like Explosive BOO.

P.S. If you found this reasoning fun, check out this earlier post on C₂O coconut water.

P.P.S. I leave you with a picture and recipe for ectoplasmic drool from this week’s Chemical and Engineering News.

Down the Rabbit Hole

How do we encourage students to delve deeper? Three incidents this past week made me think about this question. And the phrase that came to mind was “going down the rabbit hole” per Alice in Wonderland.

Incident #1: We had oral presentations in my Research Methods class. In groups of four, students were presenting their research into the serendipitous discovery of a chemical substance (e.g. nitrocellulose, lidocaine, penicillin). Part of their presentation had to touch on the role of creativity in the discovery. I went to class half an hour ahead of time, instead of the usual fifteen minutes, to load the presentations on the classroom computer. A number of students were already there! A couple were practicing their tandem talk up front. Another two were at the back philosophizing about the connection between creativity and serendipity. I joined their conversation, mostly listening and occasionally chiming in a word or two – but the students went deep into a philosophical discussion. I was thinking to myself : This is the type of discussion we should be having in class, even though it was happening “outside of class time”.

Incident #2: Two days ago I was chatting with a student about her summer research experience. As part of a Luce professorship that my department received a number of years ago, we also built in a funding line to sponsor sending two female students to R1 (research-intensive) institutions each summer. This allows our students to venture away from the very-nurturing environment of a liberal arts college that focuses on undergraduates, and get a taste of what being in a Ph.D. program might entail. The labs we send our students to are carefully chosen to ensure they have a good mentored experience. We are doing our part to increase the pipeline of women scientists in chemistry and biochemistry. Anyway, this student had an excellent experience and came back excited about graduate school and research. She talked about how she has only scratched the surface, and below that surface there’s more, and more, and more. Just like going down the rabbit hole. I’m glad we require all our majors to have an undergraduate research experience.

Incident #3: I am working on a letter of recommendation for a student I previously had in Honors general chemistry. In many ways he was your typical A student. He learned the material well, participated in class discussions, worked well with others, was pro-active about completing assignments early and not waiting to the last minute, and keeps himself busy with co-curricular activities on top of school. What made him stand out among his peers who are also typical A students was that extra depth I would see in his answers on problem set and exams. Not only would he clearly show the steps in his reasoning, his final answers had that extra bit of thoughtfulness, that showed he really understood the material conceptually. Some A students can solve problems algorithmically, but don’t necessary display the depth that made this student stand out. He went deeper.

This made me think about my general chemistry course. There is so much material to “cover” that I often do not take the time to draw the students in deep, at least in class. A student who comes by my office with questions gets that deeper treatment, i.e., I almost always respond to a question with a follow-up question to lead the student to a firmer conceptual understanding. (The initial question typically reveals the shaky foundation, but that’s part of the learning process.) I feel more at leisure in my office not to rush through an answer, even if the student would prefer just getting the answer and running off.

That’s one disadvantage of the typical chemistry major; it’s rather hierarchical. At the introductory level we have many sections of general chemistry. Students may have a different instructor in the second semester, so if I didn’t “cover” what the instructors as a group agreed upon, then I put these students at a disadvantage. The same thing happens after general chemistry when the students move on to organic chemistry in their sophomore year. Physical and inorganic chemistry come after. The advantage of a hierarchical major is that you leverage earlier material that the student knows to help them reach the more advanced material. Later courses build on earlier courses, and without completing the pre-requisite, a typical student has little chance of doing well in the next class following the sequence. Could we do all this differently? Possibly, but it would take a major redesign of epic proportions. The inertia to overcome this barrier is substantial.

But perhaps I can carve out a class period or two for some rabbit-hole pursuits. We covered properties of covalent bonds in class yesterday. Students were given data on bond lengths and energies and were asked to identify trends, anomalies, and come up with explanations. But being pressed for time, I would only ask “why” one or two levels down at most. Not far down the rabbit hole. Certainly not five levels down per the 5 Whys of the Toyota Production System. I could have restructured the material to go further down the rabbit hole, but I was blinkered by my adherence to the course syllabus. I’m giving an exam next week and wanted to make sure we “covered” the material. However, perhaps I could construct a Problem Set that requires going down the rabbit hole; this idea just popped into my head while I was typing the previous sentence – serendipity! Okay, I need to take some time to flesh out that idea more carefully.

I leave you with a “down the rabbit hole” picture that I liked from websurfing. You can see the creator’s signature in the picture. Here’s the Pinterest link, which takes you to Etsy (but I don’t have an account so I didn’t go down that rabbit hole).

Undergraduate Research: Blue-Ribbon Version

This year the National Academies Press (NAP) released Undergraduate Research Experiences for STEM Students: Successes, Challenges and Opportunities. You can read it online for free here at the NAP website. I’ve read several NAP reports pertaining to science education. Typically, a blue-ribbon panel assembles these reports narrating the current state of affairs in the field. These reports tackle multi-faceted issues with no clear-cut answers, but they bring the reader up-to-date with a summary of the evidence from the panel’s research.

The first take-home message from the report: undergraduate research experiences (UREs) in STEM are highly varied. The two most common approaches are (1) the apprenticeship model, where students work in the lab of a faculty member, and (2) embedding the experience within a course (referred to as CUREs: Course-based UREs), but there are many others. The role of the research mentor or course-instructor plays an important role in whether the student views his or her experience positively. There is some evidence that UREs have measurable positive impacts for historically under-represented groups, at least with respect to retention or persistence in STEM.

Measuring impact, however, is tricky. There are very few gold-standard randomized control trials (RCTs) measuring the effects of UREs. Trying to eliminate the effects of self-selection and other compounding factors is challenging, not to mention convincing your institutional review board to approve this type of RCT. If you were a student (or the parent of a student), you might be very unhappy finding out later that you were randomly assigned to a control group and given a “less favorable” educational experience. This is true of education as a whole; assessing the impact of different interventions can be challenging. As someone whose teaching and research spans physics and chemistry (the “harder” sciences), but who also extensively reads educational research, I have great respect for my colleagues in the so-called “softer” social sciences who contend with messier data that is much more difficult to de-convolute. It is not easy to design an experiment to cleanly separate out the particular effect of something as multifaceted as a research experience within an already complex educational experience.

How “success” is defined also varies considerably. In chapter 3, the report summarizes the many different goals into three broad categories: (1) increasing participation and retention in STEM, (2) promoting STEM disciplinary knowledge and practices, and (3) integrating students into STEM culture. Since undergraduate research is required for chemistry and biochemistry majors, I asked my students in Research Methods to critique and sharpen the vague hypothesis “Participating in undergraduate research increases student success”. (This was part of an exercise on hypothesis development a month ago.) The students caught on quickly and proposed different ways the words participate, research and success could be construed. Besides qualitative differences, we also discussed the challenge of quantifying, or coming up with a measurement acting as a proxy for a vague word in the hypothesis.

The first of the three categories may be more easily measured. For example, some of the goals listed include enrollment in STEM courses (for non-majors beyond the minimum requirement), retention of STEM majors (many students who declare a STEM major “drop out” when they realize it is “hard”), going to graduate school in STEM, or pursuing a career in the sciences post-graduation. (Many of our students go into biotech/pharma.) The other two categories are not as easily measured. I suppose students could take an exam to determine how much they know about disciplinary knowledge and practices. (We would measure if URE participants do better on the exam). Many of the studies touting the positive impacts of UREs come from self-reported student surveys. Arguably, student satisfaction is a positive outcome and it may translate into STEM careers or an appreciation for the guild of STEM, but without RCTs, it is unclear if UREs are truly “high-impact practices” (an increasingly annoying buzzword) as claimed. The panel acknowledges these limitations in their summary of studies measuring impact (in different ways), and not surprisingly, they recommend further study. (This is a common recommendation in all the NAP reports I have read.) They also conclude that there are some reasons to be optimistic as there is some (although limited) evidence for some positive impact in some areas. That’s a lot of “some”.

There are several vignettes of “successful” programs.* (This is another common feature of the NAP reports I’ve read.) These are potentially useful if one is looking for examples and ideas to emulate. The panel also does a commendable job framing UREs within the broader context of institutions and their goals. If you’re thinking of starting a URE on your campus on in your major, resources and support from the administration is needed. The NAP report is written not just for the faculty member but targets the university administrator and funding sources. It argues in support of funding UREs that align with institutional goals. In addition, research that measures the effectiveness of UREs should also be supported. A cynic might see a self-serving streak of experts in the field recommending more research, and therefore funding, is needed. But perhaps the report’s conclusion is true of any line of investigation that looks promising; further research is needed. That’s how scientists continue to make progress in their research labs, thereby contributing to knowledge as a whole (at least that is a key institutional goal for a research-oriented university). Indeed, the last words in the report’s title are Challenges and Opportunities.

My department believes UREs are so important, that we require every student majoring in chemistry or biochemistry to have a mentored research experience per the apprenticeship model. Several of our lab-based courses also have research projects built into the last several weeks. Have we quantified the impact of that experience and measured it against students who did not participate in UREs? No. And the relationship won’t be easy to untangle. We do have plenty of anecdotal data, and we have worked hard to acquire the characteristics that correlate with some measure of excellence.*

Every semester we host a Sci-Mix poster session where research labs present their work, and interested students mingle and talk science! We had our session tonight, and I’m thankful for the enthusiastic students in my group who took turns helping to answer questions, otherwise I might have been utterly exhausted. These events have become increasingly popular over the years. (We ran out of food halfway through the 1.5 hour session.) And the students seem to enjoy the mix of science. Seeing the excitement of my research students is what helps me keep going. Those individual conversations with students suggest they find what they do valuable!

*For a detailed list of requirements with brief explanations for “successful” UREs, you can look at the first chapter in the (Characteristics of Excellence in Undergraduate Research) COUER report published by the Council of Undergraduate Research.]

Fear of Failure

“Anxiety has overtaken depression as the most common reason college students seek counseling services” according to an in-depth article in the New York Times last week. The author, Benoit Denizet-Lewis, asks the question “why are more American teenagers than ever suffering from anxiety?” The article is long, and worth reading in full; I will highlight two of the reasons mentioned.

The first is fear of failure. And it’s not about over-protective helicopter parents. The pressure to exhibit success seems strongly internally driven. How can one get ahead in today’s hyper-competitive world? How does one not fall behind? The rat-race starts young. Nobody wants to look stupid, lacking or slacking. Well, it might look cool to be slackin’ if you’re also acing life. But the “look” might be exacerbating the problem, which leads to the second reason: constant access to social media. The almost instantaneous feedback loop has supercharged the urgency of maintaining one’s look. At first it may be conscious, but soon it becomes embedded in the subconscious – an agitation difficult to pin down, that in its worst scenarios leads to destructive behavior, seemingly senseless.

I’ve noticed increased anxiety in my students over the past five years, compared to the cohort from 10-15 years ago. Getting a C on an exam feels like a permanent mark changing the dream of a bright future into failing at life. Grade inflation has not helped. Neither does the rapid social media chatter extolling the high-GPA student who landed the scholarship, who was admitted into the top medical schools, who has life made. I’ve also noticed an uptick of students who want to assure me that their grade on the most recent exam doesn’t reflect their desire to learn or to persevere. The first few times I thought the students were just being conscientious. Now I wonder if it’s part of image management. They care what I think; but I’m no longer sure this is a good thing.

As a first-year student academic adviser, I see the fear of failure more prominently in the most accomplished first-year students. These are the ones who made the academic honor roll in high school, captained sports teams, were presidents of co-curricular clubs, and logged more hours volunteering in four years than I have in forty (shame on me, perhaps). I look back on my own life and my nonchalance about the lowering of my academic class standing. I was a top student in second and third grade and then just slowly slid down the hill, ever so slightly every year. I honestly don’t remember what I thought about this. It seems like a distant foggy memory. When a student advisee is freaking out in my office over that C in calculus, I try to calmly paint the long-term picture. That C does not define you, and this incident will seem insignificant in the future. It is unclear if those words have any effect.

Failure can be a key activator to learning – so long as the fear does not overwhelm. You are unlikely to accomplish anything significant if you are unwilling to work on difficult things that require perseverance, and yes, failure time and again. It is far easier to distract yourself and check your social media accounts instead of doing the concentrated hard work of learning. Yes, learning is hard – especially since what we are being taught in school is biologically secondary, and therefore requires the effort. Nor have our ancient brains evolved to sufficiently compensate for the lightning-speed distraction of our Internet-connected smart phones.

If college students today limited their social media significantly, I wonder if we would see a reduction in anxiety levels. If they were able to block out distraction-free focused time to concentrate on mastering something difficult, I wonder if the satisfaction that comes with accomplishment through perseverance will lead to less anxiety. If I checked my e-mail less often, and blocked off time to focus on my craft as a teacher – working deeply on the difficult stuff instead of shallow-level “coming up with assignments for my students” – I wonder if I would be a much better teacher. If I took some distraction-free time to think deeply about the complex questions in my research, I wonder if I would avoid shallow mucking around the edges. Is it because of fear of failure in the rat-race of academia? I’m not a rat. Why should I care if someone is moving the cheese around?

Zombie Nouns

Reading a book on improving your writing sounds tedious and boring. Not so – when the author is Harold Evans, and the book is Do I Make Myself Clear? Evans, a former editor of The Times of London, writes beautiful prose with a dollop of dry wit. His book has a varying cadence that keeps the reader engaged, the examples are exemplary, and it’s a joy to see a master craftsman at work. Language is his craft, and he wields it with sharpness. It reminds me of the biblical proverb: “As iron sharpens iron, so one person sharpens another.”

Reading Evans has made me scrutinize what I read and write. If my blog post two days ago “felt” different, I may have unconsciously imbibed lessons in his book. However, I feel I have a long way to go as a writer. I am also only halfway through his book, so I expect to discover (with horror) more examples that remind me of my inchoate writing. This past weekend I learned about zombie nouns, zoophagi orsum (flesh-eating “unnecessary words, pompous phrases and prepositional parasites”), and pleonasms. If I attempt to summarize or paraphrase Evans, I would do his writing a great injustice. The two pictures at the end of this post show his introduction to zombie nouns. If you enjoy his flavorful prose, I highly recommend getting his book and reading it in its entirety.

I leave you with three words that struck me in Evans’ list of words whose meanings are often botched.

One that I’ve used wrongly for years: Decimate. It means to kill one-in-ten. I’ve often used it to mean destroying ninety percent rather than ten percent. I should have known this. In class, I regularly have to remind students what a decimeter is.

One that I have never used, but J. K. Rowling has led me astray: Enervate. In Book 4, stunned characters are revived using the spell Ennervate. It sounds like Energy combined with Invigorate. The actual meaning of enervate is to weaken – the opposite of what you might think.

One that Rowling uses correctly, and I should have learned from her: Oblivious. I’ve used it synonymously with ignorance or clueless-ness. But that’s incorrect. It actually relates to forgetfulness. Evans writes: “If you are ignorant of something, nobody told you. If you are oblivious, somebody told you but you let it slip into oblivion.” How are memories erased in the Harry Potter world? The spell is, appropriately, Obliviate.

Synergy in Chemistry

1 + 1 > 2. True? Yes, in the world of Synergy advertisements. Synergy is one of those corporate-speak buzzwords that has invaded academia. (Are there any that haven’t invaded?) Earlier this week I read a paper from the Journal of Theoretical Biology on the role of synergy in biological evolution – and whether such synergy can be modeled mathematically. That got me thinking about where one might find synergy in chemistry. After all, chemistry is all about energy. Stick a syn in front, and maybe you can describe all of chemistry by uniting energy.

The sticky point is that synergy implies that the unity, or the whole, is greater than the sum of its parts – at least in buzzword usage. One formulation of the first law of thermodynamics says that energy cannot be created or destroyed, but it can be converted from one form to another. Energy is a shape-shifter but when you add up all its parts, the total energy cannot change. The law forbids it. Assuming you’re operating in a closed system, of course.

A similar law forms the bedrock of writing chemical equations. They must be balanced, i.e., the number and types of atoms are identical from start to finish. Assuming a closed system, of course. This is the law of conservation of matter. (We’ve ignored nuclear reactions for now where mass-energy conservation still operates.) The atoms can exchange partners in their dance, taking on new molecular shapes; but when the accountant comes a-calling, all atoms declare themselves present.

If there was an area within chemistry that might spark an inkling of synergy, it would be Catalysis. Formally, a catalyst is a substance that speeds up a chemical reaction but does not change the identity of the reactants and products. This is a textbook definition. The catalyst does its magic by lowering the activation barrier for the chemical reaction to take place. Another textbook definition. If molecules A and B normally react to form molecules C and D, then A and B first have to climb an energy hill (the activation barrier) before rolling down into their new identities C and D. Adding the catalyst does not change the outcome, but it lowers the height of the hill. Crucially, the net energy difference between A + B and C + D does not change. Since a picture is worth at least 157 words, here is an unadorned version I could find from a quick web search.

When teaching general chemistry, we make a song and dance about separating thermodynamics and kinetics. Thermodynamics tells us which direction the equilibrium state lies. Kinetics tells us how fast we will get there. Assuming a closed system, of course. And if all that existed was our isolated simple reaction of the involving our compatriots A, B, C, and D, the dance gets boring after a while.

But outside of the carefully isolated test-tube reaction, chemistry gets a lot more interesting. If there were competing chemical reactions, the dance may take you in unexpected directions depending on whether catalysts are present. Maybe A and B would form E and F instead of C and D, if an appropriate catalyst was present. A catalyst can be present in just tiny amounts to do its work. For example if you started with a thousand molecules of A and B, just ten molecules of catalyst might be enough to shunt those thousand molecules down a different path. A single Detour sign can shunt the traffic of thousands of cars. The catalyst seems to be punching way above its weight. Is this synergy?

In a non-linear web of chemical reactions, small differences in energy hills can lead to very different final product distributions. Hence, adding catalysts may change the reaction outcome – not the textbook definition. Things get more interesting if one of the intermediate molecules (or even a product) can itself catalyze an earlier step in a cascade. Such autocatalytic reactions are possibly the heart of the riddle of the chemistry of the origin of life. The big question is not how the molecules used in extant biochemistry could be formed. The big question is why life uses so few of the myriad possibilities. Any undirected chemical soup experiment produces an embarrassment of riches. What’s embarrassing: the molecules that life uses form a tiny fraction of those riches – and they don’t seem to be very different from their chemical cousins who were not “chosen” for such an honor.

Somehow, somewhere, sometime, a single-cell organism, a multi-celled organism, and a pondering creature calling himself Homo Sapiens showed up. From a chemical point of view, all three exhibit a complex web of molecules involved in an intricate dance. We don’t know where the dance is going, at least as a collective. Single organisms live and then die; we can predict their food-for-worms thermodynamic end. But a chemical world governed by kinetics defies easy prediction. Catalysts rule that world. You won’t get to your predicted thermodynamic end if you can’t get over the hill. Unless you’re in a closed system, of course, and you’re willing to wait a very, very, very long time. The future paths of evolution governed by kinetics are not known.

To “catalyze” or “act as a catalyst” are buzzwords in corporate tech-speak. Maybe this infection started from academic chemists, instead of the other way round. There are probably glossy brochures, websites and PowerPoint presentations extolling how synergy can be catalyzed – if you used product X or the services of company Y or changed Z. Can that synergy be measured? Can it be modeled mathematically? Does it mean anything if it cannot?

P.S. For the college students and professors out there, here’s something from one of my colleagues that made me laugh out loud. (Hint: It’s relevant to college-age students particularly in the U.S.)

Is the CRAAP Test crappy?

Students enjoy being introduced to the CRAAP Test. It has an amusing name, and the double A lends itself to lengthening its pronunciation for emphasis. I’ve introduced the CRAAP Test the last two times I’ve taught Research Methods, as part of a unit in searching the world wide web for information. It is also a checklist, and my students like checklists. Checklists are good things when packing your bags before a trip, or following the safety protocol before running an experiment; but are they good for learning?

What got me thinking about whether the CRAAP Test is crappy was John Warner’s post at InsideHigherEd titled Teaching Without Learning: The Limits of Checklists. Warner has taught writing for many years, notes that “checklists, often in the form of rubrics, and also often tied to high stakes assessments are ubiquitous in the teaching of writing.” I don’t have too many writing assignments in my chemistry classes and don’t use rubrics for those. My higher stakes assessments are exams and sometimes a final project. However for oral presentations, I do provide my students with a rubric of how I will be grading them.

Rubrics are the current darling of assessment strategies. A couple of summers ago, I participated in an exercise assessing student learning in general chemistry by applying a rubric to student answers on common final exam questions. The exercise itself was useful to get semi-quantitative data, and more importantly got me thinking about how students present their work when problem-solving. This led me to make modifications to some of my class activities and assessments, so in this case the exercise (while tedious) was of value to me as an instructor.

At the end of his blog post, Warner poses a number of interesting questions related to the use of checklists/rubrics in teaching. Yes, the students might be using your wonderful rubric merely as a checklist. “What if checklists are only appropriate for things we’ve already learned, but are prone to forget[?]… What is the impact of checklists on people who have not yet developed disciplinary instincts[?]” The concern arises because “tools like the CRAAP test [for literacy] are heavily domain dependent, not based on skills, but on a body of knowledge that comes from mindful immersion in context.”

Warner’s post also led me to the synopsis of a study carried out by a group at Stanford examining web literacy among grade school and college students – how to tell fake news from reliable information. Many of the suggestions of how to improve such literacy (also found on the web) are in the form of checklists, such as the CRAAP test. The author explains the problem: “The checklist approach falls short because it underestimates just how sophisticated the web has become. Worse, the approach trains students’ attention on the website itself, thus cutting them off from the most efficient route to learning more about a site: finding out what the rest of the web has to say (after all, that’s why we call it a web). In other words, students need to harness the power of the web to evaluate a single node in it. This was the biggest lesson we learned by watching expert fact checkers as they evaluated unfamiliar web content.”

What struck me most was the information gleaned by interviewing fact-checkers. Here’s an excerpt with two great quotes. “The senior fact checker at a national publication told us what she tells her staff: ‘The greatest enemy of fact checking is hubris’ – that is, having excessive trust in one’s ability to accurately pass judgment on an unfamiliar website.’ Even on seemingly innocuous topics, the fact checker says to herself, ‘This seems official; it may be or may not be. I’d better check.’ ” And I thought hubris was mainly confined to the characters of the Iliad. That’s my one word summary of the Iliad if you needed one. Hubris might also be a key theme in Quenta Silmarillion but I need to ponder that idea a little more.

The Stanford groups recommend strategies to “fend off hubris”. I recommend reading their synopsis in full for the details, but here are the three key strategies mentioned. “(1) Teach students to read laterally. (2) Help students make smarter selections from search results. (3) Teach students to use Wikipedia wisely.”

Many moons ago when I was first introduced to the Apple II, part of my time was spent finding programs that would do a better job copying other programs so I could make my own copy without shelling out cash. In the early days Disk Muncher was effective, until increased protections required more sophisticated programs such as Locksmith and their ilk. I learned early on from a DOS book that there is a constant battle between the code-protectors and the code-breakers – and that the latter will always win eventually. The checklists that we use now are likely to become obsolete quickly, at least where web literacy is concerned. The next time I teach Research Methods, I need to give a bit more thought on how I am teaching my students and whether I should toss the CRAAP Test. It might not be crappy now, but at some point it will no longer help distinguish the crap from the good stuff.

The General (Bond) Energy Curve

Over the summer, I contemplated re-thinking the way chemical bonding is introduced in General Chemistry. I decided to try the approach proposed by Nahum and co-workers, at least partially. We spent the first four weeks discussing models of the atom, the interaction of light and matter and atomic orbitals. This week we started the section of chemical bonding (approximately five weeks long).

I devoted my first class on chemical bonding to discussing the general energy curve shown above. We first discussed how the energy changes when two hydrogen atoms approach each other without discussing why. I then proposed that this curve isn’t just true for hydrogen, but it works for any atom. The equilibrium bond distances and bond energies (sometimes called bond length and bond strength) will differ for different atoms, but the overall curve is roughly similar. We then discussed the sign convention for bond breaking (energy change is positive) and bond forming (energy change is negative) relative to the zero reference state of infinitely separated atoms. The students had recently seen something similar when we discussed the orbital energies of the hydrogen atom and the Rydberg equation. I emphasized the counter-intuitive notion that energy is released when chemical bonds are formed, in analogy to conservation of energy principles when we talked about atomic emission spectra two weeks ago.

After H₂, I covered N₂ and O₂, and we contrasted the equilibrium bond distances and energies. Again, we left out the why question for now, although I alluded to atomic size being one of the factors. N₂ is a nice contrast because the bond strength is more than twice that of H₂ even though it is a longer bond. O₂ provides another interesting contrast because even though the O atom is smaller than the N atom; O₂ has a longer bond length than N₂, while its bond energy is closer to that of H₂.

Then we looked at argon. One normally doesn’t think of two Ar atoms forming a “bond” but the general energy curve still holds when two Ar atoms approach each other. The equilibrium bond distance is much longer and the bond energy is tiny (less than 1 kJ/mol compared to 436 kJ/mol in H₂). I talked about how words we use such as “bond” and “attractive force” often overlap, and technically there is no clear-cut distinction between the two. This was illustrated in the next few examples.

What if instead of atoms you had two molecules approaching each other? We used the example of two O₂ molecules – the equilibrium bond length and strength are not too different from the case of two Ar atoms. In General Chemistry this would normally be covered later in the semester under the topic of Intermolecular Forces. But I wanted to introduce them here in the context of the general energy curve. Again, we did not cover the why. The final example was the approach of the two ions K(+) and Cl(-). I chose these because they are isoelectronic to Ar. So you have a situation of two argon-like atoms (actually ions) approaching each other, but the bond energy (using Coulomb’s Law) is now closer to that of H₂ or O₂ even though the ion-pair has a somewhat longer equilibrium bond distance.

Next we talked about the source of attraction as two chemical “species” (atoms, molecules, ions) approach each other. Without going into details, we discussed electrostatics per Coulomb’s law, one-electron orbital overlap, and I briefly mentioned the idea of a dipole with scant details. I promised the students we would delve into these concepts in-depth over the next several weeks. Finally we talked about the source of the repulsion (the steep part of the curve near the left). Most instructors leave this out, or hand-wave a quick argument about nuclear-nuclear repulsion. I made it a point to talk about repulsion due to the Pauli Principle and how this would show up time and again when we discuss molecular shape and steric effects. Students often confuse the much weaker electrostatic repulsion between electrons with the much stronger Pauli repulsion. (They use the former as an explanative argument in cases when they should be using the latter.) In General Chemistry, the Pauli Principle is often treated as a quantum number rule that leads to two electrons per orbital. But it is so much more important in chemistry!

As I’ve been planning the next several classes, I’ve been inserting elements of the (Un)Happy Atoms story into the flow of my course material. I guess those hours I spent making the figures and outlining the story paid off – since I’m actually going to make use of it. How will my new approach work out? I don’t know yet, but I explained to my students why there was no assigned textbook reading for yesterday’s class, why I chose to cover the material in the way that I did with the generic energy curve, and what they should expect to see in the coming weeks. One thing I’ve learned about teaching: Context, context, context.