Physical chemistry education: its multiple facets and aspects

“Physical chemistry may be regarded as an excellent school of exact reasoning for all students of the natural sciences”

Svante Arrhenius (1859–1927)

(Theory of solutions, 1912, p. xx)

Physical chemistry (PC) is considered an essential course in the education and training not only of chemists, but also of many other specialists. In addition, the concepts, models, theories, methods and tools of PC permeate all chemistry courses at both secondary and tertiary levels. This special issue of Chemistry Education Research and Practice is dedicated to PC education and its multiple facets and aspects – historical, philosophical, psychological, conceptual, contextual, experimental, theoretical, mathematical, computational, phenomenological and molecular – as well as to its various areas, such as classical thermodynamics, electrochemistry, chemical kinetics, quantum chemistry, statistical thermodynamics, spectroscopy, etc. Many of these aspects are reflected in this themed issue.

The purpose of this editorial is twofold: (i) to provide a preview of the contributions and to outline their organisation in the themed issue; (ii) where appropriate to highlight common elements between contributions. The editorial concludes with insights into the areas for future research in PC education.

The history of physical chemistry and the role of controversies in education

The history of science plays an important part in science education, so we start this preview with the origin and history of PC. de Berg (this issue) comments that “the birth of physical chemistry was not without pain… (because) chemistry had its roots in alchemical tradition…”. In addition, de Berg cites Armstrong (1896), for whom the new chemistry, by its increased reliance on physical measurement and mathematical formulae derived from the numerical results of experiment, had led to a loss of true chemical feeling. For de Berg, “this highlights the difficulty that some chemists faced in accepting the new chemistry, physical chemistry”.

If scientists were absolutely ‘objective’, the path from data to models and theory would be free from controversy. The history of science shows that interpretation of experimental data is extremely complex. This inevitably leads to controversies, hence, making science replete with controversies. In PC, a controversy about the very existence of atoms and molecules was led by Wilhelm Ostwald, who insisted that, being not directly observable, they were hypothetical entities, and so there was no place for them in “the basic truths of science” (Sutton, 2003). Most science textbooks and curricula, however, almost completely ignore controversies. Philosophers of science refer to this deficiency as a ‘paradoxical dissociation’ (Machamer et al., 2000). In a series of studies, Niaz has demonstrated how controversies in science provide a rich background to education, helping the development of a better understanding of science by students (see Niaz, 2012).

Three papers in this issue deal with old or current controversies in PC and how these can be used for the advancement of PC education. de Berg considers the significance of the origin of PC as this is reflected in the ionists vs. hydrationists controversy in connection with the case of electrolyte solution chemistry, and in particular with the data on osmotic pressure, which led to an equation of state for aqueous solutions. Weinhold and Klein address the understanding of the true nature of hydrogen bonding, based both on quantum chemical calculations and on experimental data, with the aim of contributing to resolving the long-standing controversy between electrostatic ‘dipole–dipole’ vs. ‘partial covalency’ descriptions of hydrogen bonding. Finally, the lessons from the history of quantum physics in relation to the ongoing controversy over its interpretations and foundations are considered by Greca and Freire Jr. as a way of improving the teaching of quantum physics and quantum chemistry.

The history of electrolyte solution chemistry and its pedagogic exploitation: the ionists vs. hydrationists controversy

Kevin Charles de Berg starts from the controversy between the European school of Svante Arrhenius, Wilhelm Ostwald, and Jacobus van't Hoff (the dissociationists/ionists) who believed that salts partially dissociated when dissolved in water, and the British school of Henry Armstrong, Spencer Pickering, and George Fitzgerald (the associationists/hydrationists) who advocated the association/hydration hypothesis (today we accept that both dissociation and association occur in the solvation process). In the case of the osmotic pressure of an aqueous electrolyte solution, the ionists interpreted it in terms of the partial dissociation of the dissolved substance and were led to the van't Hoff equation in 1886. The hydrationists regarded empirical factors such as the van't Hoff factor i in the van't Hoff equation as lacking the precision demanded by chemists and mathematicians.

From the education perspective, de Berg examines the controversial character of PC and its implications for the study of the nature of science (NOS), as well as the significance of mathematics for PC in relation to the equation of state for the osmotic pressure of an aqueous electrolyte solution. The dual interpretation of the data can be used as a rich resource for demonstrating the role of scientific argument in the establishment of scientific knowledge. The author provides a list of “distinct and suitable arguments and counter-arguments” that can support “a vigorous class debate or incisive class assignment”.

Current views about hydrogen bonding – what should be taught?

Franck Weinhold and Roger A. Klein maintain that “the current tendency to strongly separate discussion of ‘true’ chemical bonding from H-bonding and related electrostatic-type ‘forces’ is deeply entrenched…”. Further, the description of chemistry as the molecular science “implicitly narrows chemistry's presumed intellectual domain to polyatomic species linked by covalent bonds”. As a matter of fact, there is a widely held view that “chemical covalency forces extend only to the boundaries of the molecule, whereas the remaining forces of intermolecular attraction (such as those responsible, e.g., for condensed phase formation, biological self-assembly, and related supramolecular phenomena) are perforce identified as ‘noncovalent’ interactions. The former are … of essential quantal nature, whereas the latter are assumed to be describable by … classical electrostatics”. Hydrogen bonding is assumed to be “the most important ‘type’ of such supramolecular interaction”.

IUPAC has recently reformulated the definition of H-bonding, by “endorsing a sensible evidence-based operational procedure for determining what is (or is not) a hydrogen bond, based on a composite array of correlated experimental properties. …The methodology suggests how one can apply standard regression techniques to quantify the relative weightings assignable to competing theories of H-bonding, with considerable conceptual and pedagogical implications”. In their paper, Weinhold and Klein, examine resonance covalence from the natural bond orbital (NBO) perspective, as well as direct and regression-based evidence, which in part “challenge electrostatic orthodoxy” and provide examples that “offer direct evidence against the textbook dipole–dipole rationale”.

According to the authors, “contrary to common textbook presumptions, all such evidence points to the superiority of covalency-based descriptors of hydrogen bonds, corresponding to intrinsic conceptual formulation as resonance-type fractional chemical bonds.” Finally, the question of “What should be taught?” about H-bonding is addressed, of which the answer involves “both narrow replacement definitions of H-bonding as well as broader changes of perspective in the teaching of Lewis structural and resonance concepts”. Five pedagogical recommendations are made starting with the recommendation that hydrogen bonding should be defined in terms of underlying charge transfer, donor–acceptor, and 3-center/4-electron resonance concepts.

Using the history of science and science education for teaching introductory quantum physics and quantum chemistry

For Ileana M. Greca and Olival Freire Jr., the interpretation of the mathematical formalism and the conceptual foundations of quantum mechanics constitute key philosophical issues. A deeper knowledge has resulted from theoretical and experimental developments that enable the testing of quantum theory in extreme situations and from a new attitude towards its foundations and interpretations. As a consequence, the authors suggest that it is necessary to modify the introductory treatment of the basic quantum mechanics concepts, in order to help students to understand them better.

According to the authors, in principle “quantum theory must be described by its own quantum mathematical formalism and … we cannot grasp it through pictures or mental images…”. However, a ‘thoughtful’ introduction of the complementarity principle will help students overcome the obstacle of illustrating the quantum world with images, such as waves and particles. Further, the authors consider a spectrum of options for the teaching of quantum physics and quantum chemistry that in their opinion are grounded in the history and philosophy of science and teaching experience. Teaching should stress quantum features such as the superposition principle and the measurement problem, as well as such effects as quantum entanglement, quantum beatings, and decoherence, in addition to the description of the current research in these topics which may be grasped at a qualitative level.

The problems associated with the conventional images of the Bohr model of an atom should be avoided by the use of very simple, dual-level systems, which show clear quantum behaviour and from which it is possible to discuss the most important quantum properties. The probabilistic aspect of quantum mechanics should be emphasised in order to prevent students from attributing physical reality (that is, deterministic models) to the mathematical constructs of core chemistry concepts, such as orbitals (see also Tsaparlis, 2013). Moreover, the fruitful results of quantum mechanics in the solution of chemistry problems, in contrast to the Bohr model, should be stressed. Historical cases following old quantum physics should be avoided. The teaching of quantum mechanics may emphasise formalism, without worrying about the ultimate ontological status of mathematical terms. The controversy over its foundations and interpretations can serve as the basis for the teaching of the historical and philosophical aspects of science. The teaching of, at least, introductory quantum mechanics for any science undergraduate student and in particular for chemistry students, should be mainly conceptual. Appropriate images could assist with conceptual understanding. Finally, it is recommended that quantum mechanics applications to real problems are included too.

Quantum chemistry

Chemical structure and bonding are key features and concepts in chemical and biochemical systems and, in addition, are used in deriving structure–property relationships, and hence in predicting physical and chemical properties of compounds. The Lewis' electron-pair mechanism provided an ad hoc model of chemical bonding, and differentiated between polar and nonpolar molecules. Quantum chemistry brought new insights to chemical bonding by describing atomic and molecular systems by means of mathematical functions and expressions that derive from Schrödinger's wave mechanics. From the quantum-chemical perspective, chemical bonding is associated on the one hand with the molecular orbital model, and on the other hand with the valence bond model. Today the development of high-level theory coupled with high-power computation facilities make feasible the execution of quantum chemical calculations of complex chemical systems (including supramolecular systems), establishing quantum chemistry as an indispensable tool in most modern chemical research. On the other hand, it is widely recognised by education researchers that the concepts of atomic and molecular orbitals, as well as other quantum concepts, are treated by the learners as having a physical reality, a physical existence (for a review see Tsaparlis, 2013). According to this view, an atomic orbital is a ‘well-defined region in space’ or an isolated carbon atom has ‘four hybrid sp³ orbitals distributed in a tetrahedron-like arrangement around its nucleus’.

In addition to the two papers by Weinhold and Klein and by Greca and Freire Jr. that were previewed above, two further papers deal with educational aspects of quantum chemistry. Dangur, Avargil, Peskin and Dori developed a module for teaching elementary quantum chemistry, emphasizing interdisciplinary real-life applications and investigated the effect of the module on the visual and textual understanding of quantum mechanical concepts. And Barradas-Solas and Sánchez Gómez examine the omnipresence in textbooks and research literature of graphical and pictorial representations of the so called ‘chemical orbitals’ as they are used to represent both chemical structures and processes (e.g. reaction mechanisms).

A visual-conceptual approach to teaching quantum chemistry

Vered Dangur, Shirly Avargil, Uri Peskin and Yehudit Judy Dori aim to tackle the problem of the qualitative understanding of the underlying principles of quantum chemistry by honours high school students and undergraduate students. To this purpose they have introduced a learning module titled Chemistry – from “the hole” to “the whole”: from the nanoscale to microelectronics, which adopts a visual-conceptual approach, integrating visual representations with textual explanations.

For the evaluation of students’ chemical understanding, the authors used the four-level model of chemistry that includes the macro, submicro, symbolic, and process levels. Their specific research objectives were: (1) to investigate the effect on the students of the visual-conceptual approach in the new module; and (2) to compare the learning outcomes of three research subgroups in terms of visual and textual understanding of chemistry in general and of quantum mechanics in particular. The qualitative analysis reflected four evolutionary stages of understanding quantum mechanics: naïve models, such as the planetary or solar system deterministic model; hybrid models that mix definite orbits of the electron with the probabilistic quantum mechanical model; a hybrid model using a mathematical formula; and the visual-conceptual quantum mechanical model. In agreement with the recommendation of Greca and Freire Jr., the historical reconstruction of the atomic model may be a source of confusion to some students. The quantitative analysis has shown that the students in this study improved their textual and visual chemical understanding skills. The authors conclude the paper by proposing the addition of a fifth level of understanding – the quantum level – to the four levels mentioned above. This level includes the ability to depict the electronic structure of atoms, molecules and solid state in terms of quantum mechanics theory. This quantum level of understanding brings to mind the quantum logic proposed by Birkoff and von Newmann (1936), which deals with the logical and mathematical structure of the theory of quantum mechanics, a theory that does not “conform to classical logic”.

Graphical representations of ‘chemical orbitals’

Francisco Barradas-Solas and Pedro J. Sánchez Gómez examine the role played by orbitals in the formalism of quantum chemistry, and in particular the use of orbitals in visual representations employed in structural chemistry arguments. The authors use examples from both textbooks and the research literature to identify an “idiosyncratic usage of orbitals”, a treatment of them “as physical objects, far from their mathematical origins”. Of special relevance in this respect is the so called ‘folk molecular theory’ (Ramsey, 1997; Sánchez Gómez and Martín, 2003), “the jumbled complex of ideas that informs the thought of chemists about the quantum realm”, an “unconventional mixture of classical and quantum concepts” that “has proved solidly useful in guiding chemical practices for decades”.

Graphical and pictorial representations of orbitals are common in any chemistry textbook (general, organic or inorganic and even at second level education), and are used to represent both the structures and processes. Reaction mechanisms and bonding schemes are perhaps the most relevant examples of these processes. The authors present a series of examples of the qualitative way chemists usually employ orbitals in their structural reasoning, often without any reference to their quantum treatment; for instance connecting the language of frontier orbitals (HOMO and LUMO) with the electron flows of classical chemistry, and thus providing the base of the curved arrow usage. In addition, the rapid evolution in recent years of computer animations of bonding and of mechanisms leads many users to feel that “they are visualizing orbitals and their interactions as they happen”.

The various examples of orbital representations used in books and the research literature are derived on the basis of varying levels of quantum chemistry theory. Some derive from qualitative or naïve models and approximations, while others derive from high-level, modern quantum chemical computations that approximate and adequately reproduce experimental data. The authors are aware that their examples come from a variety of methods and that among them there is a wide range of levels of sophistication, but they refer not to their mathematical and/or quantum-mechanical adequacy, but to their usage as chemical orbitals. In addition, the authors explicitly state their opinion that “these chemical orbitals and their accompanying quantum concepts do not pose special difficulties; on the contrary, their visual character may be an asset, so they must be present in chemical education. Moreover, the usage of a quantum-like jargon is not, in fact, a flaw, but a lexical mannerism, an idiosyncratic feature of the language of chemistry”. This is or should be – at least in part – in line with Greca and Freire Jr.'s recommendation (see above) that the teaching of introductory quantum mechanics for chemistry students should be mainly conceptual, and that images could assist with the conceptual understanding.

Thermodynamics

Classical thermodynamics is a phenomenological subject, which has been developed and can be taught without taking into account the structure of matter. It is well known that the structural concepts of matter cause great conceptual difficulties among students at all levels of education (Tsaparlis and Sevian, 2013), so one might jump to the conclusion that, compared with quantum chemistry, thermodynamics is an easy subject. This is far from true. Classical thermodynamics is very abstract and demanding in terms of both the concepts and the tools (the latter including mathematics, especially calculus).

Five papers in this issue deal with the teaching and learning of thermodynamics. Bain, Moon, Mack, and Towns review systematically the literature from different discipline-based education research resources: chemistry, physics, engineering, and undergraduate mathematics education. Nilsson and Niedderer study undergraduate students' conceptions of enthalpy, its change and related thermochemistry concepts. Making a shift from classical thermodynamics, Hernández, Criswell, Kirk, Sauder, and Rushton consider a number of issues related to the particulate-level models of adiabatic and isothermal processes in upper-level (advanced undergraduate and beginning graduate) chemistry courses. Tumay distinguishes between mental models and misconceptions and derives prospective teachers’ mental models of vapour pressure. Finally, assessment is the focus of the study by Wren and Barbera, who report on quantitative evidence for the uses and interpretations of data from their thermochemistry concept inventory.

A review of research on the teaching and learning of thermodynamics

Kinsey Bain, Alena Moon, Michael R. Mack, and Marcy H. Towns review research on the teaching and learning of thermodynamics at the university level with the purpose of making recommendations based on previous research and discussing the implications for the teaching of thermodynamics. The review is addressed to faculties who teach thermodynamics at the tertiary level and those who carry out discipline-based education research. 56 studies from many science and chemistry education research journals were reviewed. They referred to tertiary courses that included a thermodynamics component; on the one hand to physical science courses, and on the other hand (and mainly) to PC courses. Many of the studies examined student understanding of thermodynamic concepts, instructional approaches to teaching thermodynamics, or the development and validation of measurement instruments pertaining to students' conceptions of thermodynamics.

The review starts by focusing on research into factors influencing student success in PC. Then, the relationship between mathematics and thermodynamic knowledge is considered. Understanding of partial derivatives, Maxwell's relations, and differentiation in the context of thermodynamics have been examined. According to the authors, to understand thermodynamic concepts, “students must be able to translate between mathematical representations and the physical meaning they represent”. However, students “may have difficulties interpreting physical meaning from the mathematical expressions or creating mathematical expressions based upon a description of a physical process”. Also students may demonstrate mathematical proficiency even though they lack a conceptual understanding of mathematical concepts.

Despite the fact that classical thermodynamics deals with macroscopic phenomena about matter and energy, understanding and operating with the particulate nature of matter as a tool for explaining and predicting thermal and chemical phenomena is another useful area of research. Students' relevant misconceptions have also been studied. Therefore the review also focuses on the study of students' conceptions about specific topics of thermodynamics, namely, the first, second, and third laws, and spontaneity and equilibrium. Finally, directions for future research and implications for practitioners are discussed.

Enthalpy, enthalpy change and related concepts

With their study, Tor Nilsson and Hans Niedderer aim to construct students' conceptions of enthalpy, its change and related concepts through qualitative/conceptual tasks. The authors start from the tenet that “the teaching of thermodynamic concepts is based on algorithms, and teachers view qualitative understanding as a consequence of performing calculations”. As we saw above, students' mathematical proficiency does not guarantee conceptual understanding of the mathematical concepts. So introducing qualitative descriptions before calculations might contribute to overcoming the problem.

Questionnaires, examination questions, hand-outs and interviews were employed in this study. Niedderer's procedure of ‘iterative analysis’ was used for data analysis. Nine qualitative categories of conceptions were constructed, and, further, conceptions were grouped into ‘underlying’ and ‘logical’, the former denoting the general notions students use in forming their conceptions, and the latter involving the employment of specific alternative logic in the formation of the conceptions. Although such a grouping implies that the conceptions are each placed on one side of a continuum, in reality they should be regarded as more/less underlying/logical. In addition, the relationships between the conceptions are examined.

Particulate-level models of adiabatic and isothermal processes

Gabriel E. Hernández, Brett A. Criswell, Nancy J. Kirk, Deborah G. Sauder, and Gregory T. Rushton consider the following issues relating to the particulate-level models of adiabatic and isothermal processes in the upper-level (advanced undergraduate and beginning graduate) chemistry courses: (1) the students' preconceptions about gas behaviour during (pseudo) adiabatic compression and expansion of a gas; (2) the students' model(s) and rationale about observables (e.g. temperature and pressure) during the same processes; and (3) how students reconcile or revise their models based on their previous predictions when faced with experimental results that differ from what was predicted? Of particular interest among the findings are: (i) models appear to fail when the right conditions are not satisfied; (ii) the models the students invoked tended to be incomplete and/or incoherent, pointing at fragmented knowledge; (iii) students needed the instructor's intervention in order to use the particulate model; (iv) students did not appear to be comfortable with applying fundamental physics concepts of elastic collisions, speed, force, or kinetic energy to properly explain gas behaviour. Finally, the authors identify the crucial features that enable students to move between the macro, submicro, and symbolic perspectives in the context of adiabatic and isothermal processes.

Prospective teachers' mental models of vapour pressure

For Halil Tumay, focusing on the underlying sources of misconceptions and the underlying patterns in the students' reasoning is more important and useful than just listing misconceptions as a list of common mistakes or as isolated pieces of information. The distinction between ‘mental models’ and ‘expressed models’ is critical in this study, as well as the distinction between mental models and misconceptions.

After identifying prospective teachers' misconceptions about vapour pressure, the author applied the constant comparison technique and analytical inductive analysis to reveal the participants' mental models of vapour pressure. It was found that only few of the participants had constructed a scientific model and used this model successfully in explaining the vapour pressure of liquids under different conditions. Three faulty mental models emerged: (1) the vapour pressure of a liquid depends on the total number of vapour particles; (2) once the liquid–vapour equilibrium is established, the number of vapour particles is fixed and does not change; (3) vapour pressure is exerted only onto the surface of the liquid. The author points out that emphasis should be paid to teaching about the liquid–vapour equilibrium system and vapour pressure as an emergent property of that system. Experimental comparisons of the vapour pressure of different systems should be made, supported by animated or static submicroscopic illustrations to represent the dynamic nature of the liquid–vapour equilibrium system.

Assessment: the thermochemistry concept inventory

David Wren and Jack Barbera present quantitative evidence for the uses and interpretations of data from the Thermochemistry Concept Inventory (TCI), a 10-item multiple-choice questionnaire which intends to identify students' alternative conceptions regarding thermochemistry concepts. The instrument uses thermochemical alternative conceptions of college-level general chemistry students already identified through literature as the basis of distracter options, and the instrument can be used in formative and summative assessments. According to the authors, qualitative data was used to help understand and explain quantitative results, and allowed a complete appraisal of the validity of interpretations and uses of TCI testing data.

Three phases of quantitative data were collected, and the data sets were analysed separately using the dichotomous Rasch model. It was found that the TCI is unidimensional and locally independent, and that all items had acceptable infit statistics, indicating good item functioning for students within the ability range of the item. Comparison between honours and non-honours sections of the same general chemistry course revealed that the honours students did perform better as expected. Finally, the authors provide evidence that supports the validity and the reliability of the TCI data, as well as the generalisability of the instrument.

Physical chemistry textbooks

While the use of textbooks in teaching and learning in tertiary education varies across countries, universities and instructors, textbooks play a role in informing and shaping instructors' views and philosophies about the teaching content and its sequencing. On the other hand, students rely, to varying degrees, on the use of one or more textbooks for their individual study, and so it can be argued that textbooks, their scientific content, educational approach and illustrations are important for learning.

Focusing on the organisation of PC textbooks, the three principal areas of PC and their sequencing should be considered: (i) thermodynamics, which deals with the energetics of chemical reactions; (ii) quantum chemistry, which deals with the structures of isolated molecules, and (iii) chemical kinetics, which concerns the rates of chemical reactions (McQuarrie and Simon, 1997). Some authors (e.g.Atkins and de Paula, 2010) use different labels for these areas: equilibrium, structure, and change, respectively. Others (e.g.Levine, 2009) add a fourth area, that of statistical mechanics/statistical thermodynamics. In his paper, Tsaparlis examines the organisation/sequencing of the major areas of PC in PC textbooks. As an ultimate research question, the author asks if there is an ‘optimum teaching-learning sequence’ for undergraduate instruction for the various major areas of PC. According to the author, this is a controversial issue, which cannot be answered solely by the analysis of textbooks, but a wide range of information should be considered.

The logical and psychological structure of physical chemistry and physical chemistry textbooks

Georgios Tsaparlis takes Jensen's scheme for the logical structure of chemistry as reference to study the logical structure of PC, so that one can place the various PC subjects and topics in the cells of the 3 × 3 Jensen grid; for instance, phenomenological/classical thermodynamics is placed at the molar level of the energy dimension, and quantum chemistry at the electrical level of the structure dimension. In addition, the psychology of learning is used in order to analyse the psychological structure of PC. In this way, outer limits are fixed, leading to two extreme forms of ‘logic’ and hence to two alternative approaches to teaching PC, the ‘analytical, which starts with phenomenological subjects, as a rule with thermodynamics, and the ‘synthetic approach’, which begins with the structure and behaviour of matter, that is, with quantum chemistry. Very relevant here is the discussion by Peter Atkins of the evolution and the structure of PC courses, which includes consideration of the order of the PC course and the advantages of the "thermodynamics first" or the "quantum first" approach (Atkins, 2008).

The organisation/sequencing of the major areas of PC in twenty PC textbooks is then considered, with six categories of organisation identified. An account of textbooks authors' philosophies and arguments, based on the prefaces of the various books, provides justifications with respect to the structure and sequencing of the various areas of PC. Authors who favor the traditional analytical approach consider the topics of quantum chemistry, spectroscopy and statistical thermodynamics more difficult. Other authors consider that an early confrontation with quantum mechanics is advantageous to the student. However, many authors are open to alternative approaches. Finally, some authors propose the simultaneous development of classical and statistical thermodynamics, while others prefer a simple introduction to the ideas of statistical thermodynamics at the beginning.

Looking ahead: emerging themes for future research in physical chemistry education

The call for papers for this themed CERP issue included an extended list of indicative topics for contribution. They were as follows:

• The abstract nature of physical chemistry

• Conceptual understanding in the various sub disciplines of physical chemistry

• Concept learning versus mathematical approach to physical chemistry

• Assessment of physical chemistry – testing for conceptual understanding or mathematical manipulation

• Mathematical coverage and mathematical rigour: how much and how far?

• Problem solving related to physical chemistry

• The physical chemistry laboratory

• The physical chemistry curriculum

• The role of textbooks in the teaching of physical chemistry

• The interface of physical chemistry with the other branches of chemistry

• Physical chemistry in context

• Computational chemistry

• Use of symbolic mathematics engines for data analysis, model building, and problem solving

• Computer simulations and online learning in physical chemistry

• Physical chemistry concepts and topics as part of general chemistry courses at second and third level

• Reviews and perspectives (including historical perspectives).

The topics that are covered in this issue are shown in italics, while the remaining topics are not represented. Although there had been manuscripts submitted for this themed issue for some of these topics, other topics lacked submissions. In addition, two other manuscripts were still to be revised at the time of completing this editorial, so they could not be included in the themed issue. Therefore, it is considered useful to outline the key areas for future education research in the special domain of PC. For a relevant review of research in PC education, see Tsaparlis (2008).

The extent of mathematical coverage is an issue that was considered in some papers, especially in relation to the teaching and learning of quantum chemistry and of thermodynamics. In any case, this field of research has great potential for further fruitful exploitation. In particular, mathematical coverage in other areas of PC and the connection of the mathematical guise with physical interpretations deserve further investigation.

Problem solving is an essential part of PC instruction. Often, the problems involve the application of mathematical relations and tools in order to answer a set of usually quantitative questions. Excessive practice on the part of the students on such problems may turn them into routine exercises. Conceptual questions are also set. The situation with ‘real’ non-algorithmic PC problems is quite different and these problems prove very demanding for the students. Tsaparlis (2005) has carried out a correlation study of the role of a number of cognitive variables on solving the latter type of problems. On a different mode, Gardner and Bodner (2008) examined qualitatively the ‘problem-solving mindset’ of chemistry and physics students in the context of an introductory quantum mechanics course. A study into the transfer of mathematical knowledge to chemistry has suggested that the difficulties that students have of transfer between mathematical context and chemical context may be due to a lack of mathematical understanding (Hoban et al., 2013).

The PC laboratory is an integral component of the PC course. The main purposes of laboratory work are to teach hand skills and to illustrate theory or, from a different perspective, to teach not just the content of science, but also about the methods of science (Leach, 1998). In addition, practical work can stimulate students' interest and enjoyment, enhance the learning of scientific knowledge, and develop ‘scientific attitudes’, such as open-mindedness and objectivity (Hodson, 1990). However, little educational research has been carried out so far on the PC laboratory. Tsaparlis and Gorezi (2007), for instance, have investigated the addition of project-type tasks, mainly taken from articles in the Journal of Chemical Education, to a conventional expository PC laboratory, and found many positive aspects, such as the connection of chemistry with everyday life and modern applications, and the development in students of the feeling of ownership of the work. Problem-based learning approaches have been shown to be effective within laboratory teaching (Kelly and Finlayson, 2007) but again the extent of mathematical understanding may influence the student's preference for more expository activities in PC (Kelly and Finlayson, 2009).

Context-based learning uses a real-life case as the starting point in teaching, and is known to provide a rich environment for education, increasing students' level of interest and motivation. Relevant to context-based learning is problem-based learning, in which the context is established through a real-life problem (Overton et al., 2009). In the case of PC, the placing of its content in context involves not only its relevance to modern uses in everyday life, but also its applications to the other subjects of chemistry. Zielinski and Schwenz (2001) have pointed out the importance of including context-rich teaching materials in PC education. Belt et al. (2005) for instance, have developed a context-based approach to teaching aspects of thermodynamics, kinetics, and electrochemistry to early undergraduate courses.

The advantages of using computers in PC education have been recognised. For instance, Johnson and Engel (2012) have integrated a modeling exercise into the undergraduate PC course, and have reported that students found the added computation material useful and not overly difficult. The use of computers has also been highlighted in a number of papers in this issue. In connection with updating the teaching of hydrogen bonding, Weinhold and Klein (this issue) recommended that students should be exposed “ASAP to modern theoretical discovery tools … for calculating and visualizing accurate wavefunctions”. Computer simulations and online learning in PC is then another area where educational research is necessary. The availability of computer-based instructional material and resources that use models, simulations, and animations provides rich tools for educational investigations. For instance, the Digital library for physical chemistry of the Journal of Chemical Education (Zielinski, 2005) includes instructional resources that span the PC curriculum. For instance, “Quantum states of atoms and molecules” is an introduction to quantum mechanics applied to spectroscopy, the electronic structure of atoms and molecules, and molecular properties.

Regarding the various areas of PC it is apparent that the contents of this themed issue are dominated by quantum chemistry and chemical thermodynamics. Electrochemistry, chemical kinetics, statistical thermodynamics, and spectroscopy are not represented. It should be pointed out that, while there are reported studies on electrochemistry in published PC education research, there are limited studies on kinetics and few, if any, on statistical thermodynamics and spectroscopy. Statistical thermodynamics serves as a bridge between quantum chemistry and thermodynamics, and as such it should be of particular interest from the educational point of view. On the other hand, spectroscopy has a direct relationship with quantum chemistry (but also with statistical mechanics), and if this is coupled with the fact that it has observable examples (the spectra) and many applications, it is evident that it must be challenging to explore its educational aspects.

Finally, PC textbooks certainly offer further opportunities for various types of content analysis regarding not only their textual features (conceptual and mathematical approach) and their visual representations, but also their questions, problems, home assignments and projects. Of special interest is the analysis of electronic materials (CDs and links to web-based materials and resources), including the development and use of digital textbooks.

Postscript: controversies and disjunctiveness in physical chemistry education

At the beginning of this editorial, Svante Arrhenius' statement was invoked that “physical chemistry may be regarded as an excellent school of exact reasoning”. Of course, one could interpret “may be regarded” as “may or may not be regarded”. On the other hand, the ‘exactness’ of the subject should be distinguished from the exactness of the scientists' thinking. The latter should be connected to the fact that science is replete with controversies and disjunctiveness, and we can extend this to science education research, a main purpose of which is to attempt to resolve controversies and disjunctiveness about teaching and learning science. The study of this themed issue of CERP shows that controversies and controversial or bipolar issues are abundant and can be very fruitful for PC education: ionists or hydrationists? dipole–dipole or partial covalency descriptions of hydrogen bonding? particles or waves? physicists' or chemists' orbitals? Bohr's deterministic model or the quantum mechanical model of chemical bonding? visual representations or textual explanations of quantum chemical concepts? mathematical representations or physical meaning? rigorous or surface mathematical coverage of PC? misconceptions or mental models? phenomenological/macroscopic or particulate-level models of thermodynamic systems? phenomenological thermodynamics or quantum chemistry first? And so forth, and so on.

The Disjunctive Conjunction “Or”

(excerpt) †

… the brazen god of war let loose a shriek, roaring,

thundering loud as nine or ten thousand combat soldiers

shriek with Ares' fury when massive armies clash.

–ILIAD

[…]

Oh that “or”:

an expression both of mockery and of courtly precision,

an equivocal smile out of an incommunicable and nonparticipating wisdom

[…]

knowing full well that precision is unachievable,

that precision does not exist (which is why the pompous air

of certainty is so unforgivable […]).

“Or,” disjunctive conjunction, modest outcome of the mystery of uncertainty,

profound response to the multiplicity of essences and phenomena,

through you we accommodate […]

the many nuances and aspects of the black down to invisible white.

Yannis Ritsos‡

(June 18, 1969)

Acknowledgements

The editors of this themed issue thank all the authors for their contributions, which have shaped a very rich in content and valuable set of papers. They are also grateful to the reviewers of the submitted manuscripts for their expert and detailed feedback that contributed greatly to the improvement of all papers. Last but not least, we thank the editor of CERP, Dr Keith S. Taber, for his constant and very active involvement in the whole review process, both as coordinator of the process and as provider of personal comments and advice to the authors.

References

1. Armstrong H. E., (1896), Letters to the Editor, Nature, 55(1413), 78.
2. Arrhenius S., (1912), Theories of solutions, New Haven: Yale University Press.
3. Atkins P., (2008), The evolution of physical chemistry courses, in Ellison M. D. and Schoolcraft T. A. (ed.), Advances in teaching physical chemistry, Washington, DC: American Chemical Society/Oxford University Press, pp. 44–55.
4. Atkins P. and de Paula J., (2010), Physical chemistry, 9th edn, Oxford: Oxford University Press.
5. Belt S. T., Leisvik M. J., Hyde A. J. and Overton T. L., (2005), Using a context-based approach to undergraduate chemistry teaching – a case study for introductory physical chemistry, Chem. Educ. Res. Pract., 6, 166–179.
6. Birkoff G. and von Newmann J., (1936), The logic of quantum mechanics, Ann. Math., 37, 835–843.
7. Gardner D. E. and Bodner G. M., (2008), Existence of a problem-solving mindset among students taking quantum mechanics and its implications, in Ellison M. D. and Schoolcraft T. A. (ed.), Advances in teaching physical chemistry, Washington, DC: American Chemical Society/Oxford University Press, pp. 155–173.
8. Hoban R. A., Finlayson O. E. and Nolan B. C., (2013), Transfer in chemistry: a study of students' abilities in transferring mathematical knowledge to chemistry, Int. J. Math. Educ. Sci. Technol., 44, 14–35.
9. Hodson D., (1990), A critical look at practical work in school science, Sch. Sci. Rev., 70(256), 33–40.
10. Johnson L. E. and Engel T., (2012), Integrating computational chemistry into the physical chemistry curriculum, J. Chem. Educ., 88, 569–573.
11. Kelly O. C. and Finlayson O. E., (2007), Providing solutions through problem-based learning for the undergraduate 1st year chemistry laboratory, Chem. Educ. Res. Pract., 8, 347–361.
12. Kelly O. C. and Finlayson O. E., (2009), A hurdle too high? Students' experience of a PBL laboratory module, Chem. Educ. Res. Pract., 10, 42–52.
13. Leach L., (1998), Teaching about the world of science in the laboratory: the influence of students’ ideas, in Welllington J. (ed.), Practical work in school science: which way now? Routledge, pp. 52–68.
14. Levine I. N. (2009), Physical chemistry, 6th edn, New York: McGraw.
15. Machamer P., Pera M. and Baltas A. (ed.), (2000), Scientific controversies: philosophical and historical perspectives, New York: Oxford University Press.
16. McQuarrie D. A. and Simon J. D., (1997), Physical chemistry – a molecular approach, Saulito California: University Science Books.
17. Niaz M. (2012). From ‘science in the making’ to understanding the nature of science: an overview for science educators, New York: Routledge.
18. Overton T. L., Byers B. and Seery M. K., (2009), Context- and problem-based learning in higher education, in Eilks I. and Byers B. (ed.), Innovative methods of teaching and learning in higher education, Cambridge: RSC Publishing, pp. 43–59.
19. Ramsey J. L., (1997), Molecular shape, reduction, explanation and approximate concepts, Synthese, 111, 233–251.
20. Sánchez Gómez P. J. and Martín F., (2003), Quantum versus ‘classical’ chemistry in university chemistry education: a case study of the role of history in thinking the curriculum, Chem. Educ. Res. Pract., 4, 131–148.
21. Sutton M., (2003), The father of physical chemistry, Chemistry World, Issue 5, May 2003, http://www.rsc.org/chemistryworld/Issues/2003/May/physicalchem.asp, accessed 28 May 2014.
22. Tsaparlis G., (2005), Non-algorithmic quantitative problem solving in university physical chemistry: a correlation study of the role of selective cognitive variables, Res. Sci. Technol. Educ., 23, 125–148.
23. Tsaparlis G., (2008), Teaching and learning physical chemistry – review of educational research, in Ellison M. D. and Schoolcraft T. A. (ed.), Advances in teaching physical chemistry, Washington, DC: American Chemical Society/Oxford University Press, pp. 75–112.
24. Tsaparlis G., (2013), Learning and teaching the basic quantum chemical concepts, in Tsaparlis G. and Sevian H. (ed.), Concepts of matter in science education, Dordrecht: Springer, pp. 437–460.
25. Tsaparlis G. and Gorezi M., (2007), Addition of a project-based component to a conventional expository physical chemistry laboratory, J. Chem. Educ., 84, 668–670.
26. Tsaparlis G. and Sevian H., (2013), Introduction: concepts of matter – complex to teach and difficult to learn, in Tsaparlis G. and Sevian H. (ed.), Concepts of matter in science education, Dordrecht: Springer, pp. 1–8.
27. Zielinski T. J., (2005), Introducing JCE LivTexts: physical chemistry, J. Chem. Educ., 82, 1880.
28. Zielinski T. J. and Schwenz R. W., (2001), Teaching chemistry in the new century: physical chemistry, J. Chem. Educ., 78, 1173–1174.

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Footnotes

† Yannis Ritsos. Yannis Ritsos, Repetitions, Testimonies, Parentheses. Translated by Edmund L. Keeley. © 1991 Princeton University Press. Reproduced by permission of Princeton University Press.

‡ Greek poet (1909–1990).

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