27 Jul 2009

First Day Review of Atomic Orbitals

In-Class Activity

Submitted by Maggie Geselbracht, Reed College
Categories
Prerequisites: 
Corequisites: 
Course Level: 
Description: 

This is an interactive small-group discussion activity I did on the first day of sophomore-level inorganic chemistry to get students to interact with each other and brainstorm to collectively review what they knew about atomic orbitals.  I also wanted to "set the stage" for non-lecture type activities in this class.  I adapted this in-class activity from one posted by Joanne Stewart (Hope College) with additional questions from a fundamental quiz posted by Barbara Reisner (James Madison University).

Learning Goals: 

After this in-class review a student should be able to:

  • Describe a  number of different meanings for the term "orbital"
  • Recall the values of the quantum numbers for a particular orbital including their significance
  • Sketch simple pictures of the atomic orbitals including the locations of both angular and radial nodes
  • Describe the relative energies of atomic orbitals as a function of principal quantum number and effective nuclear charge
Related activities: 
Implementation Notes: 

I left the last 20-25 minutes of the first day of class for this activity.  I wanted a way to get all the ideas from General Chemistry about atomic orbitals out on the table without having to spend lecture time on it.  I was able to look through the group worksheets afterward and used this feedback in planning my first real "lecture" on atomic structure.  For example, I compiled a list of all the things the students told me that the term "orbital" meant and highlighted particular meanings that I wanted to connect to.  That was a great lead-in to my lecture. 

For the activity itself, I let students self-select into groups of 4 and asked them to assign the roles to each group member as described on the handout.  In most cases, groups of friends worked together, although we had an interesting diversity of student backgrounds in this group including some second-semester freshpeople through seniors and several students who had already completed quantum mechanics.

Time Required: 
20 minutes
Evaluation
Evaluation Methods: 

I collected the group worksheets and used them as a first peak at the "ready-recall" knowledge that different students were bringing to the class (although I was not able to single out individual responses from the group) and where the class stood as a whole in their understanding of atomic orbitals.  

Evaluation Results: 

I have attached a document with a list of all the ideas the students came up with for the term "orbital" as well as how many groups answered each of the other questions correctly and some of the common errors.

Creative Commons License: 
Creative Commons Licence

Comments

Thanks to all for the ideas about this learning object! I did it today as a first day activity. I used groups of 3 instead of 4 (my class is small!) and I changed the orbitals to draw to ones with specific orientations. I don't think my students did as well as Maggie's. I wonder if it is because of a summer off, smaller groups, or some other reason! I am giving them a chance to redeem themselves though! My versions and evaluations are listed above now as well.

I implemented this in-class activity during the second 50-minute lecture of the semester.

  • The class is composed of 22 juniors and seniors.
  • Nineteen students began study at a variety of community colleges.
  • Fifteen students completed General Chemistry I at nine different community colleges, and four took Gen Chem II at a different location than Gen Chem I.
  • Thirteen students enrolled in Physical Chemistry II in an earlier semester
  • Four students were repeating the course.  
A few weeks before the semester started I e-mailed the class a list of topics to review/expected prerequisite knowledge, and provided them with review materials.

The groups did well at recalling the n and l quantum numbers. The groups struggled, with less than half answering correctly, on questions about shading, nodes, shapes, ml and energy levels. Three of the five groups could not correctly identify the values of n, l, and ml given an orbital designation with open notes/open book as a reference.

Initially I added a few questions about MO theory because this is part of our curriculum in General Chemistry I, but I removed them before giving this exercise.

Given that a relatively small percentage of the students took the general chemistry courses in our curriculum here in their freshman year, the activity was helpful in that it gave additional insight about the need to review these topics in class and to assign additional homework material on these concepts to ensure students have the necessary background.

I like your implementation Michael! Next time, I think I might allow open book answers, and I might also change the initial brainstorming prompt to "atomic orbital" because many of my students were just coming out of organic, so many of their comments were more MO based. I did encourage them to take clean copies home with them to complete as they did the initial reading on quantum theory.

I implemented this in-class activity yesterday as a review for a J-term organometallic undergraduate course.

The class consists of 6 students; 3 just finished the first semester of organic chemistry and the other 3 finished both semesters of organic chemistry.

I did not inform my students to review before hand, but I let them answers the questions with an open book (Organometallics, Spessard and Miessler 2nd edition).

Like Michael's class, the group did well recalling the quantum numbers but struggled with the angular, radial nodes and the energy levels.  Then, I quickly did a lecture on Atomic orbitals, then Molecular orbitals.

I found that the students were more interested in hearing the succeeding lecture because the questions in the activity are still in the minds.

Thank you for a very good resource.

Marites A. Guino-o, University of St. Thomas, St. Paul, MN 55105

Thanks for the very helpful comment, Tess! Can't wait to hear more about how things are going at St. Thomas!

I used this on the second day of our one-semester inorganic course with mostly juniors, and some sophomores and seniors. I had 14 groups of 3. I used Hilary's version of the worksheet (Orbitals_inclass1_MG_HJE.doc).

I told my students to review ahead of time and I showed them a short video about orbitals.

All of them got the first two questons correct about n and l, and 12/14 groups got the third question correct about what the colors represent.

Only 2/14 groups were able to answer question 4 about angular and radial nodes. This is not something we usually cover in gen chem and they obviously did not pick it up from the reading.

11/14 were able to draw the shapes of orbitals but only 1/14 indicated the signs of the wavefunctions.

12/14 got the assignments of n, l, and ml correct.

No one knew that the 2s and 2p in hydrogen are the same energy. 13/14 knew the 2s in helium is lower in energy than the 2p. 6/14 knew the energy of the 2s orbital in hydrogen is greater than the energy of the 2s orbital in helium.

In summary, I learned that most of the students were able to answer questions based on gen chem material, but almost none were able to answer questions based on the reading. Perhaps this will have served as a lesson that they need to work harder toward understanding the reading.

we did this on day 1 of my inorganic class, almost all juniors who have had a year of organic and a year of pchem as prereqs.  I used the MG_HJE version and I had 5 groups of 3-4.  We did not review or prep in advance, the students were "cold."

brainstorming got a lot of mostly correct ideas out. Questions 1-3 were all right, but question 4 was harder. only 2 groups got all 4 right; the most common problem was not knowing how many radial nodes there were.  Most got angular nodes correct for all 4.

orbitals pictures, all had right general shapes for 3s and 3px, but one group did not include the interior radial nodes.  2 groups got the dx2-y2 right, and 3 had no idea what that orbital was.

Question 6, almost perfect;  one group left m-sub-l blank for the last 2.

question 7, only one group got all 3 right, 4 groups missed a and c and I think most groups were guessing and guessed lucky for 7b.  

I will review these results and discuss the right answers briefly at the beginning of class tomorrow.

I used this on the first day of my sophomore/junior-level inorganic course.  I used the MG_HJE version, although I re-ordered the questions a little bit to begin with items that I expected that the students would remember.  I put the question about sketching orbitals first and followed that with quantum numbers.  I didn't do any review or assign any reading first, so this was just based on what students remembered from previous courses.

Students were very receptive to working in groups.  There was a rather large range in how well students could recall the concepts.  Most groups came up with a number of generally correct ideas during the brainstorming session.  Most groups drew the orbital shapes and orientations correctly, but several didn't include radial nodes.  Most groups were able to identify quantum numbers associated with particular orbitals, and 9 of 11 groups correctly answered the questions about n and l.

More groups had trouble with questions about nodes, so this is definitely an area I will emphasize in the second lecture.  Only one group knew that 2s and 2p are equal in energy in H, but 8 of 11 groups knew that 2s is lower in energy than 2p in He.

I used this on day 2 of my junior/senior level class today. One group knew that the 2s and 2p of hydrogen had the same energy. All the groups knew that the energy of the 2s for He is less than the energy of the 2p. Some groups were able to identify quantum numbers for a given orbital. I suggested they bring in their GChem textbooks to help them with this exercise. Most students did not and were trying to recall concepts from memory. I had six groups for this exercise.

Sibrina

I completed this activity this week. None of the groups knew that the 2s and 2p of hydrogen had the same energy. Love this activty. Intro chem review is key to get off to a good start.

We just finished this activity in class today (soph/jr level inorg I).  I see a lot of comments here about how no students know the 2s and the 2p of hydrogen have the same energy.    True for my students as well.  Led to really good discussion about how these orbital energies slide around.  Perfect lead in to the more complicated 3d-4s crossing (Rich) that we will talk about on Thursday.

I used this activity in the first day of my junior/senior course today.  I re-arranged the order along the lines that Katie Oertel described, and I left off the H vs He comparison in the interest of time.  I think it was a good review - most groups got the grid problems correct, though most also neglected radial nodes on their orbital drawings.  And as usual, students don't have a good grip on the d orbital shapes just yet.  (But that will change!) 

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