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I do not like to take a large amount of time in class to cover nomenclature of any kind, though I want students to know the names of common ligands and the basic ideas of how coordination complexes are named. Since it is a systematic topic I assign this guided inquiry worksheet. I guess I think about it like learning rules for a new board game, sometimes you just have to play and learn as you go. This assignment is meant to establish teh basica rules for naming by guiding students through what the needs are in naming, then it allows them to identify the convetions from a list of structures with their names and compositions.
My students typically complete this entirely outside of class and can work at whatever pace they want. If they are more familiar with the topics the can quickly complete it but if they are rusty or have not seen some of the material it gives them an easy entry point to ask questions to fill in any gaps in their knowledge. This assignment covers determing charge on a metal in a complex with simple ligands, how to identify and name common isomers, and it is structured in a guided inquiry form.
| Attachment | Size |
|---|---|
| updated worksheet (summer 2020) | 186.29 KB |
| updated worksheet pdf (summer 2020) | 587.92 KB |
Students will be able to identify and correctly name common ligands in a chemical structure or chemical name.
Students will be able to identify the charge on a metal or a ligand in a chemical structure.
Students will be able to identify common isomeric differences in a chemical structure or a chemical formula (cis, trans, fac, mer).
Students will be able to use a chemical name to draw a chemical structure. (I always clarrify that my learning objective is that students read a name and draw a structure and not the other way around. My rational is that chemical bottles have names and not pictures on them)
None but there is a nice guide from IUPAC that lists out all the rules in great detail.
https://iupac.org/cms/wp-content/uploads/2016/07/Inorganic-Brief-Guide-…
I use this assignment to replace a lengthy lecture on the topic of nomenclature when covering coordination chemistry. I have students complete this assignment outside of class. I encourage them to work in pairs so students can jointly interpret the instructions and determine the patterns in naming complexes. The assignment is constructed in a very straightforward manner and covers the basics of inorganic nomenclature.
I have tried in more recent semesters to get this assignment out to students very early in the semester during a lab period that isn't completely taken up by that days lab work. That way they more naturally work with someone else, their lab partner, and I can answer some of the logistical type questions about how to work through the assignment before they get too far.
I have taken about 15-20 minutes in class to quickly cover the main ideas of the assignment, but this isnt what I do anymore. I now just tell students that there are going to be questions on the upcoming exam, I tell them the format will match the assessment questions in this assignment, and challenge them to make sure they understand the content. I try to direct any questions that arsie to office hours or email.
Evaluation
For my course I grade this assignment as a problem set. Upon collecting the assignment I usually scan the first pages of the document to make sure they are compelte and I grade more closely the four assessment questions at teh end of teh assignment. I tell the students when I hand it out that it is designed for them to learn and then test their own comprehension and if they are stuck they should bring issues to office hours.
On the following exam I put two or three inorganic complex names and have the students draw the structures. The test questions always incorporate isomerism in addition to combinations of common ligands and transition metals. I started tracking student's correct responses on the ACS Foundations of Inorganic exam but I do not have any pre/post data for comparison. I dont have a lot to say here because of the newness of the test and that I couldnt' use it Spring 2020 because of the shutdown.
After completion of this assignment most students are able to draw straigthforward structures including some isomers on an exam. They can identify common ligands from their names like water, ammonia, carbon monoxide. They also understand the common conventions in naming including handling cis and trans isomers as well as fac and mer isomers.
In the most recent sample of ACS examinations (IN16D) 87% of my students answerd correctly on the question most directly related to this assignment, selecting the correct name of a given complex using a picture of the complex. I do not have any comparative data from another teaching approach.
I used this worksheet in class last week on our first day of coordination compounds. The students hadn't really seen too many coordination compounds yet in class (except as point group assignment examples), because we've been doing a lot of group theory and bonding. I thought this worksheet was a great way to introduce them to the typical conventions in inorganic, both in terms of naming but also in figuring out the charge on the metal, etc.
It did take my group (n = 19 students) pretty much the entire hour to work through the problems. I can see why you'd assign this outside of class! But I didn't mind using the class time. It was a very nice way for them to build their own knowledge. Thanks!
I modified this as an in-class activity. We used just pages 3 and 5 of the worksheet, and I provided them with the figure 1 of structures. The students needed~20 min to complete this in pairs. They were really quick at picking up on some of the general naming rules. Since I skipped over the first page that goes over determining charge on the metal (oxidation state), students did have a few questions on that, but I went over questions they had after the worksheet and was able to help them with this.
My students even noticed a few small errors. In figure 1, the complex shows Pd, but the structure lists Pt. In question 2 on page 5 the name is "potassium trans-diacetylacetonatodicyanoferrate(III)" shouldn't the name be "trans-bisacetylacetonato"
Overall, this was a great activity for teaching naming and helping the students realize the "rules" for themselves. I plan to adopt this for all future classes.
I have used this LO the last two years in my inorganic course. I have done it both as an in-class guided inquiry exercise that was not collected but we went over the answers in class, and as an out-of-class exercise that I collected and graded (mostly for completeness, not correctness). I think this is a fantastic way to teach nomenclature because it walks the students through examples of ligands and complexes and shows /why/ we need to have different prefixes and names. Thanks, Gary!
The glitch that my students caught this past spring was mer-Triaquatribromocobalt(III) chloride on page 5. mer-Triaquatribromocobalt(III) would be neutral.
Thanks for the edits Alexis and Kevin. I made some updates and reposted the assigment and answer key.
the updated LO and answer key were removed when we moved to the new server. I had downloaded them, so I put them back. Thanks for the updates Gary!
I used this LO with a small group of High School students I taught in Summer 2020. They had some nomenclature resources available to them (chemistry libretext online pages) but they did this as homework and for the most part were able to get answers mostly correct. A few minor mistakes here and there. they will be responsible for accurate (although not IUPAC-level accurate) names later in the course so this was a good exercise to put on them and not take up the valuable 90 minutes of class time I have per week.