Tuesday, February 3, 2015

Memorizing the periodic table seems like a waste of time to me

Sparked by a tweet from Anne Helmenstine (About.com's chemistry expert) suggesting ways that students can memorize the periodic table, I was amused to find that some tweeps had strong feelings about the memorization of the periodic table: 
@stephengdavey: I can think of literally no reason to want to do this. Never once had a chemistry exam where this was a requirement. 
@jkemsley:  To be clear: IMO it's ridiculous to require students to memorize the PT. Understand? Yes. Memorize? No.
I am not an expert in the pedagogy of chemistry, but it seems to me that there is a lot more to be gained from the understanding of why the periodic table is organized in the fashion that it is, as opposed to memorization of where the elements are. Understanding the trends in electronegativity, atomic number, size (or memorizing them, even) would seem to me to be far more important.

I think it's fair to expect upper-level undergraduates and graduate students to have significant chunks (transition metals, etc.) of the periodic table memorized, more as a byproduct of familiarity than an actual end goal. (Here's one professor who expects this.)

From a practical perspective, I am always under the impression that most high school and early college students have access to the periodic table for exams. Does anyone out there require memorization of the whole periodic table? It's definitely a neat parlor trick, but why?

(To a great extent, this is part and parcel of the seeming resistance of the majority of chemists to memorization. For example, there's no better way to get a bunch of organic chemists really upset than to say "o-chem is just a bunch of memorization.")


  1. In high school, I had to memorize the first 20 elements in order. (Yes, there were fewer elements back then.)

    At two different recent trivia nights there have been periodic table questions:

    How many elements start with the letter Z?
    What letter does not appear on the periodic table?

    Not sure if having the whole thing memorize would have helped, but I did get all kinds of grief for having to think about the answers.


  2. We had an old stick-in-the-mud professor for two semesters of inorganic (s and p block followed by d and f block) who required that we had the whole thing memorized by the end of the sequence. In the end, I could do it for the final but the only benefit was lots of practice with mnemonics.

    Several years removed from that I can't fill in the whole thing anymore, however I definitely know all the elements that I work with on a semi-regular basis. Ultimately, I think that you should be familiar with the positions/reactivities of elements that are relevant to your work: this familiarity should fall naturally out of use (and practicality) rather than being mandated by some draconian professor.

  3. We had to do this in an upper level undergrad inorganic chemistry class at the end of the semester. Basically it taught me how to come up with many 'creative' mnemonics for one test. I don't remember what the professor's justification was. The class was probably the most rigorous and integrative course in undergrad (and I found it more challenging than p-chem!), but I can't say having the periodic table memorized for a few hours (cramming plus exam) has helped me much.

  4. I used to teach inorg chem in a bsc and msc course. Memorization of the whole periodic table was absolutely essential (at taught msc level), as our students had to memorize chemical properties of most elements (and their compounds) anyway.

  5. You can't teach about "why" to folks who don't know "what". Chemistry is not about memorization, but without memorization there is no chemistry. In order to understand facts and concepts, you need to learn them first, and this includes a fair bit of memorization.

  6. inorganic, sophomore undergrad - If i recall, we had to memorize all of the transition metals for all of the tests, and it was itself a graded exam question. "sketch the d elements, w/ atomic numbers and valencies". Maybe not the first exam, but thereafter? I distinctly remember it being a key feature of the course.

    There wasn't really any tangible merit to this - there were some metals that we obviously knew from practice, but that would have come from practice problems and not the memorization. For oddball transition metals on tests, its not as though I'd have thought "Oh, of course Dubnium [least, if ever used for questions], its...", I would just consult the little d-block I had sketched out on page 1. Pretty unfortunate - like above anonymous, the course was challenging in the right way, with a stellar professor, but the memorization bit was stupidly archaic.

  7. comparatively, when I had to take a full-on inorganic class as a grad student (despite being in the organic division. whatever my grad school was weird), we did not have to memorize the transition metals.

  8. As an inorganic chemistry student, I had to memorize the periodic table for two classes in undergrad and once for a grad course. (Interestingly, the graduate professor was the former student of one professor, and the former adviser of the other professor.)
    The justification was that someday you'll be in an organometallic seminar, and the presenter will say, "We were using metal X, and we decided to try metal Y." The benefit is that you'll know immediately that metal Y is one to the right of metal X or one below, or whatever, without having to ask. You'll know whether it's bigger, whether the new complex has a different charge, etc. Not every lecture hall will have a periodic table. Some presenters (including those you might want to impress) will assume you know it. Therefore, you should learn it early.
    I found it annoying at the time, but I do agree with the justification, and knowing the table has helped me just like they said it would.
    By the way, they did not make us memorize the f-block, or any of the numbers, just the positions.

  9. Scott E Denmark required it around 2004.

    I've since forgot it all but the elements that I use at least every 2years.

  10. My very first university professor (general chemistry course) taught us we should use the periodic table as a keyboard: you don't have to know it by heart, but know where to find the element when you're searching it. Still not sure what he really meant, but that's a nice way of looking at it

  11. Undergrads at Oxford have to learn the periodic table, it's not provided in exams.

  12. Learned it in high school for AP Chem, then re-memorized the important part for my undergrad Organometallics class.

    I focused on organic instead of biochem in college because the first day of biochem was "memorize the amino acids."

    If you want to get pedagogical, *all* higher-order thinking depends on the ability to memorize low-level stuff. You can't speak German if you don't know any verbs, you can't build a house if you only know how to use a hammer, an you sure as hell can't do organic chemistry if you only know the Grignard.

  13. I took a class my first year of PhD that required memorizing the table. Filling in a blank periodic table was extra credit but you definitely needed the points to get a good grade in the class. While my memory is horrible I can still recite certain columns/rows and can fill in the whole table given a little time (more than 5 years later). At the time I thought it was really stupid but I have used the skill since when discussing related elements at over coffee or lunch but obviously this could be done with a pocket periodic table also.
    I agree that if you don't know how the periodic table is structured then memorizing where things are is not relevant but if you understand the structure memorizing sections can be very useful for quick recall.

  14. We were required to memorize the table in mid-school. Transition metals were messy for me. Didn't understand why that time and of course cursed at the requirement. I agree with CJ, it does help understand element properties better, which I realized after entering grad school.

  15. I can confirm that the Oxford undergrads have to memorise it - we weren't given one for any of our finals. It didn't seem fair at the time (especially when one of our questions expected us to know the electron configuration of thorium), but now that I'm a few years on from that I'm glad I did memorise it. It hasn't faded from my mind unlike a lot of my undergraduate chemistry, and it helps me to remember the all-important principles behind the periodic table which, no doubt, I'd have forgotten otherwise.

  16. MPK, I think that at under graduate and post graduate chemistry programs one is expected to memorize PT. Something very wrong/stupid with the delivery model. Probably the University and Faculty are both archaic and dumb. With proper delivery model and practice one would be a natural at PT. I understand at school and high school since PT is not provided to students at exams memorization improves efficiency in solving problems.