Incorporating Tactile Learning into Periodic Trend Analysis Using

Article Cite This: J. Chem. Educ. XXXX, XXX, XXX−XXX

pubs.acs.org/jchemeduc

Incorporating Tactile Learning into Periodic Trend Analysis Using Three-Dimensional Printing Robert J. LeSuer* Department of Chemistry and Biochemistry, The College at Brockport, SUNY, Brockport, New York 14420, United States

J. Chem. Educ. Downloaded from pubs.acs.org by UNIV OF SUNDERLAND on 10/29/18. For personal use only.

S Supporting Information *

ABSTRACT: Consumer-grade manufacturing tools such as 3D printers are becoming increasingly prevalent in STEM education environments, especially as tools to develop inexpensive, tactile visualization models. Presented here is a workflow for creating 3D-printed periodic tables displaying a variety of trends from traditionally taught relationships such as atomic radius and ionization energies to less-frequently visualized distributions such as abundance in the human body and the number of stable isotopes. The process is facilitated by the use of Mathematica, which is used for both access to elemental data and generation of the file to be sent to the 3D printer. Since Mathematica is available for free for educational use on the Raspberry Pi, it is possible to use the procedures presented even under resource-limited conditions. An example group work activity is presented in order to demonstrate how the 3D-printed tables can be used in a classroom setting. KEYWORDS: Hands-On Learning/Manipulatives, Interdisciplinary/Multidisciplinary, High School/Introductory Chemistry, Periodicity/Periodic Table

■

INTRODUCTION The concept of periodic trends, introduced in general chemistry and typically revisited in later courses, is an important one for students to grasp, as it demonstrates how atomic number and structure influence the properties of elements. Students must recognize not only that periodic trends exist,1 but also how factors such as effective nuclear charge and the properties of atomic orbitals influence physical properties of atoms such as radii and ionization energies. The importance of periodic trends is reflected in the recent update to the ACS Exam Institute’s anchoring concepts content map, where it was placed under anchoring concept I.C.2 Often, students struggle with counterintuitive relationships, such as the decrease in atomic radius with increase in atomic number across a period of the periodic table.3 Additionally, there is evidence to suggest that students cannot readily recognize periodic trends from elemental data.4 To facilitate conceptual learning, general chemistry textbooks often utilize a threedimensional bar chart. These images attempt to display a three-dimensional or topographic periodic table, where the height is related to the property of interest, even though students often lack the necessary graphical literacy to make use of these figures. Graphical literacy is a critical competency in writing within the sciences, with several case studies identifying 3D computer model design as an important outcome in engineering-based programs.5 However, it is not clear if the pedagogical emphasis on design rules results in a student’s ability to understand and assess the information presented in sophisticated graphics.6 Alternatively, plots of physical proper© XXXX American Chemical Society and Division of Chemical Education, Inc.

ties as a function of atomic number can be used to explore periodic trends. Limiting the focus of the plot to a subset of elements can emphasize trends (and deviations there from); however, attempting to display trends across the entire periodic table in a single Cartesian plot is challenging. There exists a wide variety of resources related to teaching about periodic table trends and concepts.7 Advances in computer visualization techniques have allowed for the development of software packages that display periodic properties in three dimensions.8 Attempts to explore periodic trends with physical three-dimensional tables have recently included the use of interlocking toy building blocks (e.g., Lego).9 These models, and others,10 are shown to be beneficial in assisting nonvisual learners and have been incorporated into hands-on activities and general chemistry demonstrations. The process of building a block-based periodic table is timeconsuming; the “resolution” of the blocks may be insufficient to depict deviations from trends, and the use of multicolored blocks may provide a sensory disturbance to the overall learning goals. Other nontraditional methods of visualizing periodic trends include diffusion cartograms, which use the size of the element symbol block to express the relative magnitudes of the property of interest.11 Novel methods of periodic table representations were deemed sufficiently important to warrant Received: July 23, 2018 Revised: October 12, 2018

A

DOI: 10.1021/acs.jchemed.8b00592 J. Chem. Educ. XXXX, XXX, XXX−XXX

Journal of Chemical Education

Article

Figure 1. Example Mathematica code to generate the atomic radius 3D periodic table. See text for brief descriptions of these commands. Further details are provided in the Supporting Information.

its designation as a theme for National Chemistry week12 and are the subject of several scholarly debates.13 Additive manufacturing techniques such as 3D printing can be used to create physical models of periodic tables that represent trends in a topographic manner. 3D printing has been used in many chemistry-education settings that benefit from visual and tactile modes of information transfer. Atomic orbitals can be printed for a fraction of the cost of commercial analogues, even if 3D printing services are employed.14 Similar to what has been done with 3D printing of crystallographic unit cells,15,16 one can envision printing the same models/ periodic table on multiple scales for personal, group, and lecture-based instruction. Another interesting use of 3D printing in chemistry instruction is the presentation of molecular potential energy surfaces.17 A particularly innovative approach to teaching VSEPR theory involves students drawing structure templates with handheld 3D printing pens,18 although the authors do recognize that current technological barriers made the project challenging to implement. In addition to the specific examples presented above, several papers describe the process for creating chemistry-related 3Dprinted models.19 One challenge in using additive manufacturing for chemistry-related models is the need to include support material to produce a successful design. In such cases, it is often easier to submit a design to a commercial printing company, which increases the time and expense of a design. Because a topographic periodic table is a surface projected into a third dimension containing no overhanging elements (in machining parlance, it is 2.5D), fabrication of a topographic periodic table is straightforward on consumer-grade printers and does not require considerations of support material as is typical of other chemistry-related 3D printing projects such as chemical structures or atomic orbitals. A more significant challenge is a software package and workflow that are capable of creating three-dimensional shapes and have access to the elemental data. Mathematica, from Wolfram Research (Wolfram.com), readily addresses both of these challenges since it is possible to design three-dimensional objects programmatically, and the software comes with access to a database of elemental information. While many academic institutions are capable of providing students and staff with

access to Mathematica, the software licensing may be cost prohibitive in some circumstances. Fortunately, Wolfram Research partnered with the Raspberry Pi Foundation (Raspberrypi.org) in order to provide the software, free of charge for personal and educational uses, on the Raspberry Pi, a single-board computer that enables technology enthusiasts to develop inexpensive instrumentation and educational solutions.20 The $35 Raspberry Pi computer is capable of running the Linux operating system and is equipped with USB and HDMI ports to connect typical computer interface components (e.g., monitor, keyboard, mouse), has onboard WiFI and Bluetooth connectivity, and comes with a general-purpose input/output (GPIO) interface that is used to connect the computer to sensors and actuators. The Raspberry Pi can even be incorporated into customized research instrumentation when costs of commercial alternatives become prohibitive.21 What follows is a summary of the workflow for designing and printing a 3D-printed periodic table and a case study demonstrating the use of the objects in a classroom setting. The Supporting Information provides the Mathematica code and detailed instructions for reproducing the models presented here.

■

OVERVIEW OF PRINTING METHOD Fabrication of a topographic periodic table requires the following steps: • starting Mathematica and loading the periodic trends (PTrends) package; • selecting a periodic trend, which can come from those available from within Mathematica or a customized trend imported from a spreadsheet; • creating a three-dimensional cityscape object of the desired size; • optionally adding title text to the object; • exporting the object as a stereolithography (STL) file; and finally • submitting the STL file to a 3D printer. An example of this process is shown in Figure 1, and detailed instructions on using the package can be found in the Supporting Information. Once the periodic trends package is loaded with “≪ PTrends.wl”, creating the object with the B



Article

Figure 2. Three-dimensional printed periodic tables depicting trends in atomic radius printed on (left) Stratasys Connex3 polyjet printer, (middle) Prusa MK2S FDM printer using PLA filament, and (right) Makerfarm i3v FDM printer using PETG filament and hand painted.

Table 1. Comparative Print Times for Selected Sizes of Periodic Tables Depicting Atomic Radii Table Parameters Title

Text

Block Size, mm

Dimensions,a mm3

Print Time,b min

Object Volume,b mL

Comment

Yes No No No

Yes Yes No No

8 6 3 1.6

54 × 150 × 21 42 × 114 × 13 24 × 60 × 11 10.6 × 29.8 × 10

180 90 42 12

47.5 17.8 4.4 1.1

Shown in Figure 2 Smallest block size with rendered text Painted objects in Figure 3 Smallest printed table attempted

a Measurements are given for the finished length, width, and height. bVolumes and times reported by Slic3r version 1.39 for the Prusa MK2S FDM printer.

desired dimensions requires two commands. First, “GetInfo[]” is used to obtain the elemental data and format the values for printing. The second command, “makeSTL[]”, generates a three-dimensional object which is then converted to a stereolithography (STL) file using “Export”. The STL file generated in this fashion can be transferred to the computer controlling a 3D printer for printing or uploaded to a 3D printing service. The final command “table // pretty” optionally displays the final object that will be printed. More sophisticated trends require additional processing, and a number of examples are provided in the Supporting Information. Several representative examples will be shown to demonstrate the flexibility and adaptability of this project. Techniques described here were tested using two fused deposition modeling (FDM) kit-based 3D printers (8″ i3v from Makerfarm and MK2S from Prusa) and a commercial polyjet printer (Objet500 Connex3 from Stratasys). The thermoplastics used for FDM were PETG, a derivative of polyethylene terephthalate, and polylactic acid PLA (both from GizmoDorks). Digital objects were created using either Mathematica version 11.2 on a model 3 Raspberry Pi or version 11.3 on a Windows 10 platform and subsequently exported as stereolithography (STL) files. Objects were then printed with a layer height of 0.2 mm with heated bed and hotend temperatures set to the values recommended by the printer vendors for the plastics used. Postprocessing included

sanding and painting, although these procedures were not required.

■

REPRESENTATIVE EXAMPLES Wolfram maintains a number of curated data sets, one of which is ElementData. The sources used by the software package can be found on the company’s Web site.22 Of the 86 properties in this database, 56 are numerical and could be used for periodic trend explorations. One of the first periodic trends introduced to students in a general chemistry setting is atomic radius, which displays a counterintuitive decrease in size with increasing atomic number within a period. Figure 2 displays 3D-printed models of periodic tables with element block heights proportional to atomic radii. The Mathematica code as written (see Supporting Information) defaults to printing only the s-, p-, and d-blocks, since the properties depicted in the prints are not known for many of the f-block elements. However, it is possible to include the f-block elements as desired. A scaling factor is then applied to the atomic radii to create an object with the desired height. Using a z-height of 18 mm and a layer height of 0.2 mm resulted in an object with sufficient resolution to differentiate visually the atomic radii of tantalum and tungsten (200 and 193 pm, respectively) but not tantalum and niobium (198 pm). The length and width of the final object can be adjusted as well and are limited by the printer characteristics (e.g., hot-end diameter and bed C



Article

Figure 3. Representative trends that can be printed. Top three models were printed using a polyjet printer, and bottom three were printed using a FDM printer and hand painted. Top models represent electronegativity, electron affinity, and ionization energy. Bottom models depict density, number of stable isotopes, and ionization energy.

Figure 4. The d-block portion of a 3D-printed periodic table displaying the trend in element density with braille lettering.

dimensions) and the desired print time. Since the printing time is largely dependent on printer parameters, it is difficult to predict the time a particular model will take to build. Listed in Table 1 are print times for several representative periodic tables on the Prusa MK2S. Figure 3 highlights the variety of periodic table designs that can be created using this method. Printing trends such as ionization energies require preprocessing of the height data, since the curated data set stores a list of all ionization energies known for each element. Because the data set and object creation are performed within the same software package, manipulation of the data is straightforward, and an example is provided in the Supporting Information. With the ability to manipulate the data, it is possible to create more unusual periodic tables such as the number of stable isotopes. From this depiction, students can readily recognize that elements with an even number of protons have a larger number of stable isotopes and identify some outliers such as technicium, which is the only element with atomic number below 83 having no stable isotopes, and tin, which displays the greatest number of

stable isotopes. Last, topographic models are not limited to the properties stored in the curated data set. For example, visualizing Pearson’s absolute hardness23 can be realized by creating a new data set from the ionization energy and electron affinity.

■

USE AND PRACTICAL CONSIDERATIONS On the kit-based printers used in this work, hand-sized objects with dimensions of 80 × 25 × 20 mm3 weigh between 5 and 10 g. Objects of this size are too small for legible text, and symbol names are omitted. While a block size of 6 mm provides the smallest footprint (108 mm, excluding the base) with legible text, larger objects with lengths of approximately 150 mm, corresponding to a block size of 8 mm, are of a suitable size for group work. Even using a relatively expensive thermoplastic, PETG in this case, the material cost for printing these objects using FDM-based printers is less than $1 (in 2018 dollars). Commercial printing companies can be used to provide objects with higher resolution or novel materials at added costs ranging from approximately $20 for fused deposition modeling D



Article

group was relying on resources beyond the 3D-printed periodic table to answer questions. A critical-thinking question asked students to predict the order of several elements not presented on the 3D-printed table: “The 3D printed table does not contain the 7th period elements nihonium (Nh), radium (Ra), and bohrium (Bh). Given that nihonium is in the p-block, radium is in the s-block and bohrium is in the d-block, predict the relative sizes (smallest to largest) of these three elements.” One group answered the question correctly with a list of the three elements. One group provided a complete sentence that correctly identified the relative sizes, but in the opposite order of what was asked: “Ra would be the largest, Bh would be the middle size, and nihonium would be the smallest.” (Italics added.) The remaining groups provided lists in an incorrect order. Interestingly, one group annotated their worksheet with the colors of the 3D-printed periodic table that corresponded to the individual blocks, suggesting that multicolored objects may facilitate answering questions of this nature. General comments from the students indicated that the novelty of the 3D-printed tables facilitated learning of the material; however, the objects used in this exercise (90 mm in length) were found to be small for working in a group.

to $50−100 for laser sintered plastics. The multicolored polyjet-printed objects shown in the previous figures cost approximately $36 each. Once a user becomes familiar with the Mathematica software package and the 3D printing tool chain, it is possible to create a periodic trend learning tool in response to the learning environment. For example, in discussing the electron configurations of transition metals, exceptions to the Aufbau principle are often cited as due to the “stability of a d5 configuration”, an argument which has come under some scrutiny.24,25 By printing a topographic periodic table of the number of electrons in the outermost subshell, students can easily visualize which elements do not follow the Aufbau principle and begin to assess the validity of the arguments posed. Use of topographical periodic tables therefore allows the instructor to shift the students’ cognitive behavior from remembering a fact to analyzing claims made about data, and may contribute to a student’s ability to assimilate trends in elemental properties.26 Last, customization options include the ability to change the font, which opens the possibility to generate 3D periodic tables with braille lettering. Standards for embossed braille on paper are likely relevant to 3D-printed braille objects as well.27 In order to meet these standards, a block size of 11 mm is necessary, which results in a full periodic table approximately 200 mm wide. A demonstration of how to generate brailleembossed periodic tables is provided in the tutorial document. A representative example is shown in Figure 4. The flexibility provided by the process described here opens up a large number of possibilities with regards to teaching diverse populations.

■

CONCLUSION Consumer-based additive manufacturing can provide easily accessible, inexpensive tools to enhance instructional delivery of traditional general chemistry concepts. Coupling 3D printing with inexpensive hardware such as the Raspberry Pi and educational licensing of programming and knowledge platforms such as Wolfram’s Mathematica further decrease the barrier to implementation. With the scripts and examples included in the Supporting Information, novice users of Mathematica and those new to 3D printing can easily generate periodic tables containing their desired information and within a few hours have a functional model.

■

GUIDED INQUIRY Included in the Supporting Information is a guided inquiry activity designed to assist students in using the atomic radius and ionization energy periodic tables. While guided inquiry lessons exist for high-school level instruction,28 this activity was designed to introduce periodic trends to a class consisting primarily of nonmajors in health professions. There were 17 students self-selected into groups of 3−4 and provided the activity and two 3D (polyjet)-printed periodic tables. In the 50 min allotted for the activity, students were able to complete all of the questions related to atomic radius but had insufficient time to go through more than the first few questions of the ionization energy section. The activity was not designed to assess the efficacy of using the 3D-printed periodic tables; however, several observations provide insight into student engagement with the objects and course material covered in the activity. The provided periodic tables only contained elements up to atomic number 86, yet two of the 5 groups answered the question “How many periods and groups are there in the 3D-printed periodic tables?” with 7 periods rather than 6, suggesting that students were not restricting their answers to the 3D-printed periodic table and may have been using the periodic table poster in the lecture room or their textbooks as well. All groups were able to correctly describe the general relationship between atomic radius and period or group. When asked to focus on a particular block, 4/5 groups correctly identified the largest atom in the s-block; 3/5 identified the largest atom in the d-block, and 2/5 identified the largest atom in the p-block. For the p-block question, one group swapped the correct answers for p- and d-block and one group answered “Fl” suggesting, among other things, that this

■

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available on the ACS Publications website at DOI: 10.1021/acs.jchemed.8b00592. Tutorial document providing detailed instructions on periodic table design process (PDF) Wolfram Mathematica package for generating periodic tables for 3D printing, including a Wolfram Mathematica notebook providing instructions and tutorial for designing periodic tables, and an Excel spreadsheet template and example completed template for important custom trends into the Mathematica notebook (ZIP) Example in-class activity using the atomic radius and ionization energy trends, with answer key available from the author (PDF) STL files for several trends (ZIP)

■

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Robert J. LeSuer: 0000-0001-7193-0780 Notes

The author declares no competing financial interest. E



■

Article

(21) Maia Chagas, A.; Prieto-Godino, L. L.; Arrenberg, A. B.; Baden, T. The €100 Lab: A 3D-Printable Open-Source Platform for Fluorescence Microscopy, Optogenetics, and Accurate Temperature Control during Behaviour of Zebrafish, Drosophila, and Caenorhabditis Elegans. PLoS Biol. 2017, 15 (7), e2002702. (22) ElementData Source InformationWolfram Language Documentation. http://reference.wolfram.com/language/note/ ElementDataSourceInformation.html (accessed Oct 2018). (23) Pearson, R. G. Absolute Electronegativity and Hardness: Application to Inorganic Chemistry. Inorg. Chem. 1988, 27 (4), 734− 740. (24) Vanquickenborne, L. G.; Pierloot, K.; Devoghel, D. Transition Metals and the Aufbau Principle. J. Chem. Educ. 1994, 71 (6), 469. (25) Meek, T. L.; Allen, L. C. Configuration Irregularities: Deviations from the Madelung Rule and Inversion of Orbital Energy Levels. Chem. Phys. Lett. 2002, 362 (5), 362−364. (26) Hartman, J. R.; Nelson, E. A. Do We Need to Memorize That?” Or Cognitive Science for Chemists. Found. Chem. 2015, 17 (3), 263− 274. (27) Size and Spacing of Braille Characters. http://www. brailleauthority.org/sizespacingofbraille/ (accessed Oct 2018). (28) Trout, L. POGIL Activities for High School Chemistry; Flinn Scientific: Batavia, IL, 2012.

ACKNOWLEDGMENTS This work has been supported in part through start-up funds provided by the College at Brockport, SUNY. The author thanks Elizabeth Koprucki of the Polsky Center for helpful discussions and assistance with printing on the Objet500 Connex3 printer.

■

REFERENCES

(1) Franco-Mariscal, A. J.; Oliva-Martínez, J. M.; Blanco-López, Á .; España-Ramos, E. A Game-Based Approach To Learning the Idea of Chemical Elements and Their Periodic Classification. J. Chem. Educ. 2016, 93 (7), 1173−1190. (2) Holme, T.; Luxford, C.; Murphy, K. Updating the General Chemistry Anchoring Concepts Content Map. J. Chem. Educ. 2015, 92 (6), 1115−1116. (3) Osman, K.; Sukor, N. S.; Osman, K.; Sukor, N. S. Conceptual Understanding in Secondary School Chemistry: A Discussion of the Difficulties Experienced by Students. Am. J. Appl. Sci. 2013, 10 (5), 433−441. (4) Larson, K. G.; Long, G. R.; Briggs, M. W. Periodic Properties and Inquiry: Student Mental Models Observed during a Periodic Table Puzzle Activity. J. Chem. Educ. 2012, 89 (12), 1491−1498. (5) Danos, X.; Barr, R.; Górska, R.; Norman, E. Curriculum Planning for the Development of Graphicacy Capability: Three Case Studies from Europe and the USA. Eur. J. Eng. Educ. 2014, 39 (6), 666−684. (6) Carpenter, J. H. A “Layered Literacies” Framework for Scientific Writing Pedagogy. Curr. Teach. Learn. 2011, 4 (1), 17−33. (7) Jacobsen, E. K. National Chemistry Week 2009: ChemistryIt’s Elemental! JCE Resources for Chemistry and the Periodic Table. J. Chem. Educ. 2009, 86 (10), 1154. (8) Saleem, S. GraphOverflow: 3D Periodic Table of Elements. http://graphoverflow.com/graphs/3d-periodic-table.html (accessed Oct 2018). (9) Melaku, S.; Schreck, J. O.; Griffin, K.; Dabke, R. B. Interlocking Toy Building Blocks as Hands-On Learning Modules for Blind and Visually Impaired Chemistry Students. J. Chem. Educ. 2016, 93 (6), 1049−1055. (10) Fantin, D.; Sutton, M.; Daumann, L. J.; Fischer, K. F. Evaluation of Existing and New Periodic Tables of the Elements for the Chemistry Education of Blind Students. J. Chem. Educ. 2016, 93 (6), 1039−1048. (11) Winter, M. J. Diffusion Cartograms for the Display of Periodic Table Data. J. Chem. Educ. 2011, 88 (11), 1507−1510. (12) Saecker, M. E. Periodic Table Presentations and Inspirations. J. Chem. Educ. 2009, 86 (10), 1151. (13) Scerri, E. The Periodic Table. In Philosophy of Chemistry; Hendry, R., Needham, P., Woody, A., Eds.; Elsevier North Holland: Oxford, Amsterdam, 2012; Vol. 6. (14) Griffith, K. M.; Cataldo, R. de; Fogarty, K. H. Do-It-Yourself: 3D Models of Hydrogenic Orbitals through 3D Printing. J. Chem. Educ. 2016, 93 (9), 1586−1590. (15) Rodenbough, P. P.; Vanti, W. B.; Chan, S.-W. 3D-Printing Crystallographic Unit Cells for Learning Materials Science and Engineering. J. Chem. Educ. 2015, 92 (11), 1960−1962. (16) Scalfani, V. F.; Vaid, T. P. 3D Printed Molecules and Extended Solid Models for Teaching Symmetry and Point Groups. J. Chem. Educ. 2014, 91 (8), 1174−1180. (17) Lolur, P.; Dawes, R. 3D Printing of Molecular Potential Energy Surface Models. J. Chem. Educ. 2014, 91 (8), 1181−1184. (18) Dean, N. L.; Ewan, C.; McIndoe, J. S. Applying Hand-Held 3D Printing Technology to the Teaching of VSEPR Theory. J. Chem. Educ. 2016, 93 (9), 1660−1662. (19) Chen, T.-H.; Lee, S.; Flood, A. H.; Miljanić, O. Š . How to Print a Crystal Structure Model in 3D. CrystEngComm 2014, 16 (25), 5488−5493. (20) Urban, P. L. Universal Electronics for Miniature and Automated Chemical Assays. Analyst 2015, 140 (4), 963−975. F


Incorporating Tactile Learning into Periodic Trend Analysis Using

Recommend Documents