An official website of the United States government
Abstract Students in a second semester general chemistry course used quantum chemical calculations to investigate and reinforce general chemistry concepts. Students explored the isomers of hypochlorous acid, made predictions of miscibility via dipole moments calculated from ab-initio means, experimentally validated/disqualified their miscibility predictions, and used molecular models to visualize intermolecular attraction forces between various compounds. Student responses in pre-/post-exercise assessments show evidence of student learning. Responses in pre-/post-exercise surveys showed an increase in student understanding of basic concepts and of the importance of quantum mechanics in common general chemistry topics.
more »
« less
Exploring Student Misconceptions in Bonding and Resonance: A Computational Chemistry Exercise for General Chemistry Laboratory
An in-silico exercise was developed for a general chemistry laboratory course at St. Bonaventure University in which students examined potential energy surfaces, molecular orbital diagrams, and how bond orders and Lewis structures are connected. Pre- and post-assessment data suggests that, though students learned from the exercise, they are not connecting the concepts of bond order, Lewis structures, and resonance. There was a statistically significant improvement in the assessment scores before and after the laboratory experiment, and there was no statistical difference between the post-assessment and the follow-up assessment, which occurred after students completed the lab report 1 week after the initial experiment. The data suggest an improved understanding of computational chemistry concepts as well as improvement in the individual concepts of resonance, Lewis structures, and bond orders. However, an assessment question connecting these concepts did not show an improvement. An additional questionnaire was conducted to explore this discrepancy. This study indicates that more investigation is necessary with regard to students’ ability to make logical connections among bond orders, Lewis structures, and resonance.
more »
« less
- Award ID(s):
- 2142874
- PAR ID:
- 10548155
- Publisher / Repository:
- Journal of Chemical Education
- Date Published:
- Journal Name:
- Journal of Chemical Education
- Volume:
- 101
- Issue:
- 10
- ISSN:
- 0021-9584
- Page Range / eLocation ID:
- 4381 to 4389
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Emerging technology combining spectroscopy with microscopy is advancing the analysis of trace evidence with the potential to revolutionize forensic microscopy and excite a new generation of forensic microscopists. In this laboratory experiment, developed for undergraduate forensic chemistry and instrumental analysis courses, students use Fourier transform infrared (micro)spectroscopy (µ-FTIR) to analyze mock forensic samples commonly encountered at crime scenes, including latent fingerprints (laced with ibuprofen to mimic an illicit drug), vehicle paint chips, and acrylic fibers. Unlike light microscopy, µ-FTIR provides information on the spatial distribution and chemical nature of the sample. Learning objectives were to reinforce key concepts covered in the classroom, including collection and preparation of trace evidence, forensic microscopy, and vibrational spectroscopy, as well as to provide students hands-on experience using a state-of-the-art instrument. Students prepared the fingerprint and fiber samples for analysis, whereas the paint chip was previously cross-sectioned to save time. The students collected and processed their own data, including generating chemical distribution maps. Student responses to the exercise were positive and reports written by the students demonstrated an increased awareness of the capabilities of FTIR microscopy and chemical imaging. Overall, the exercise helped remove the “black box” mentality, where students analyze samples without understanding the fundamentals of the technique, which is so important to recognize poor data quality and troubleshoot instruments. This report describes the laboratory exercise and student experience, and includes data and chemical images collected by students, and aspects of the experiment that could be modified to improve learning outcomes.more » « less
-
t has been shown that active learning strategies are effective in teaching complex STEM concepts. In this study, we developed and implemented a laboratory experiment for teaching the concepts of Boolean logic gates, molecular beacon probes, molecular computing, DNA logic gates, microRNA, and molecular diagnosis of hepatocellular carcinoma, which are related to DNA molecular computing, an interdisciplinary cutting-edge research technology in biochemistry, synthetic biology, computer science, and medicine. The laboratory experience takes about 110–140 min and consists of a multiple-choice pretest (15 min), introductory lecture (20 min), wet laboratory experiment (60–90 min), and a post-test (15 min). Students are tasked to experimentally construct three molecular logic circuits made of DNA oligonucleotides and use them for the fluorescence-based detection of microRNA markers related to diagnostics of hepatocellular carcinoma. The class was taught to undergraduate students from freshman to senior academic levels majoring in chemistry, biochemistry, biotechnology, and biomedical sciences. Students were engaged during the session and motivated to learn more about the research technology. A comparison of students’ scores on the pretest and post-test demonstrated improvement in knowledge of the concepts taught. Visual observation of the fluorescence readout led to a straightforward interpretation of the results. The laboratory experiment is portable; it uses inexpensive nontoxic reagents and thus can be employed outside a laboratory room for outreach and science popularization purposes.more » « less
-
Educational research supports incorporating active engagement into K-12 education using authentic STEM experiences. While there are discipline-specific resources to provide students with such experiences, there are limited transdisciplinary opportunities that integrate engineering education and technological skill-building to contextualize core scientific concepts. Here, we present an adaptable module that integrates hands-on technology education and place-based learning to improve student understanding of key chemistry concepts as they relate to local environmental science. The module also supports disciplinary core ideas, practices, and cross-cutting concepts in accordance with the Next Generation Science Standards. We field-tested our module in three different high school courses: Chemistry, Oceanography and Advanced Placement Environmental Science at schools in Washington, USA. Students built spectrophotometric pH sensors using readily available electronic components and calibrated them with known pH reference standards. Students then used their sensors to measure the pH of local environmental water samples. Assessments showed significant improvement in content knowledge in all three courses relating to environmental relevance of pH, and to the design, use and environmental application of sensors. Students also reported increased self-confidence in the material, even when their content knowledge remained the same. These findings suggest that classroom sensor building and collection of environmental data increases student understanding and self-confidence by connecting chemistry concepts to local environmental settings.more » « less
-
Holme, Thomas A (Ed.)The phenomenon of fluorescence is very important from multiple standpoints in the chemical and biological sciences. This paper introduces an experiment in a first-semester chemistry laboratory course that uses a current biomedical research method, the detection of double-stranded DNA using the intercalator propidium iodide. Fluorescence is detected both using blacklight illumination and also with white light and a spectrometer, using the two excitation bands for propidium. This experiment also involves students obtaining DNA from strawberries and then determining the amount of DNA they have isolated using fluorescence methods. The experiment provides students with an initial experience in fluorescence-based analytical chemistry and the concepts of fluorescence as a quantum phenomenon.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1021/acs.jchemed.4c00694
