The second unit in my sequence for AP Chemistry covers the new AP Chemistry Course and Exam Description Learning Objectives associated with atomic structure. I will identify and describe activities I use to teach students some of the Learning Objectives that I tie into this unit consisting of nine class days.
My atomic structure unit only includes atomic structure and electron configurations (1.5 days), photoelectron spectroscopy (1.6), mass spectroscopy (1.2), and the electromagnetic spectrum (3.11 and 3.12). (Periodicity is in my unit 3.) We start with a brief year 1 review of atomic structure including the subatomic particles’ charge, location, and masses with ions and isotopes. We review the theory of atomic structure leading up to the quantum mechanical model. This was all covered in year one so I do it in one period, but in years when I taught AP chemistry as a first year course, all of this material was learned using the flipped classroom videos prior to the start of this unit with 1-2 periods of practice problems. I still cover magnetism because I have the students observe materials (Zn, Fe, MnO2, KMnO4, CuSO4, etc) to determine their magnetic properties and propose a rule of thumb after writing electron configurations and drawing orbital notations. I find it is great practice of these skills and shows a good application of electron configurations, although magnetism is no longer tested on the AP Chemistry Exam (see figure 1). See the supporting information for a handout.
Figure 1: Students observe magnetic properties of metals
We move on to a card sort (created by Jamie Flint) in which students are given various electron configurations and PES diagrams and asked to match them together (see figure 2). This is a great way to have students think critically about what the graph is trying to depict without having taught PES yet. It really saves a lot of lecture time and helps them construct their own ideas about the graphs to give the students ownership of the material and help with their long term memory of the objective. We practice PES more after reviewing ionization energy and binding energy (year 1 concepts for me). We contrast the PES graphs with mass spectroscopy graphs to do another card sort (also created by Jamie Flint). I like to challenge the students’ thinking by showing mass spectroscopy graphs of diatomic elements as discuss what graphs of compounds can be used for in my flipped videos.
Figure 2: Electron configuration and PES cardsort
The second portion of my unit includes light equations to calculate the wavelength, frequency and energy of light. We practice numerous questions in which we solve for single photons using wavelengths in meters and nanometers. We identify what type of radiation we are calculating using an electromagnetic radiation poster. To gain more practice and an understanding of why this is important for the atomic structure unit, we view the bright line spectra of hydrogen, helium, and neon and compare to published values. Then we calculate the wavelength, frequency and energy of the lines we observed. We do not have fancy equipment so we make qualitative measurements and relate those colors to published values (see the attached lab). We calculate the level from which certain electrons fall just for understanding, though it is not on the AP Exam. Although it is a lot of calculating, my students love viewing the spectra and value the practice more than a normal worksheet. See the supporting information for a handout.
Some people have asked how I structure homework. My school district requires us to give homework and count it as ten percent of the students’ quarter average. I provide a flipped video that I have made each night (except nights before exams) using the free Edpuzzle website. I post all videos at the start of the unit so students have time to watch them at their own pace. I also ask students to complete one written homework assignment per unit. The written assignments contain 2-3 very old AP exam questions along with a reading and my own questions (all of these homework assignments can be found on my website www.chemisme.com). I know the students can easily find the answers and copy them for the old AP Exam questions but we discuss the value of trying the examples on their own and using the answers found online as a way of checking their work and learning from their errors. The homework is for practice, and without practice, they will not succeed. The completion of homework has little bearing on their overall grade, and the questions I wrote on the homework will be weighted more.
What activities do you include for these learning objectives? How do you handle homework assignments in your classes? Please join the conversation on ChemEd X!