Georgios Tsaparlis

Atomic orbitals, molecular orbitals and related concepts: Conceptual difficulties among chemistry students

Students start the undergraduate quantum chemistry course with incomplete knowledge and many conceptual difficulties about quantum-chemical concepts. This work investigated the impact an undergraduate quantum chemistry course has on students’ knowledge and understanding of atomic orbitals, molecular orbitals and related concepts. A “post-factum” analysis of examination data from this course reveals that students; do not have a clear understanding of the concepts of atomic and molecular orbitals as well as of Slater determinants; have difficulty in understanding the conceptual similarity between real and complex mathematical forms of atomic orbitals; confuse the various atomic orbital representations; and, do not realise the approximate nature of atomic orbitals for many-electron atoms. Difficulties with other related concepts are revealed also. Some promising strategies for instruction and suggestions for secondary and general chemistry curricula are discussed.

A model of problem solving: Its operation, validity, and usefulness in the case of organic‐synthesis problems

The Johnstone–El-Banna model of problem solving is based on working-memory theory as well as on Pascual-Leones M-space theory. The operation and validity of the model depends on a number of necessary conditions, such as a simple logical structure, availability and accessibility of the partial steps, absence of “noise,” and lack of familiarity with the problem type. If these, and some other conditions, are not fulfilled, the model may not operate; that is, solvers may be successful, even if the information-processing demand (Z-demand) is greater than their information-processing capacity and, vice versa. Sixteen organic chemical-synthesis problems, with a simple logical structure and varying Z-demand from 2 to 8, were used in this work. We studied two samples of students (age 17–18), one without (N = 128) and the other with (N = 191) some previous training (at least in part) in organic-synthesis problems. Although the predicted pattern was observed in both samples, it was found that the model was more useful in the case of the students without previous training. Finally, the model predicts better with the field-independent and the field-intermediate students, but less so with the field-dependent ones.

Non‐algorithmic quantitative problem solving in university physical chemistry: a correlation study of the role of selective cognitive factors

This work provides a correlation study of the role of the following cognitive variables on problem solving in elementary physical chemistry: scientific reasoning (level of intellectual development/developmental level), working‐memory capacity, functional mental (M) capacity, and disembedding ability (i.e., degree of perceptual field dependence–independence). Nine individual studies, with seven problems and with various samples of first‐year undergraduate chemistry students at the University of Ioannina, were used. The problems were open‐book, while the students were as a rule not supplied with the necessary data (facts, figures, values of constants, etc.). The results were analysed by calculating Spearman’s ρ and Pearson r correlation coefficients. In addition, the seven individual studies were combined using a quasi meta‐analysis (n = 250). The main findings are: (1) scientific reasoning showed lack of correlation; (2) working‐memory capacity also showed weak correlation, but stronger than scientific reasoning; and (3) functional M‐capacity and disembedding ability played a very important role. The field may thus be of paramount importance in the novel (for the students) non‐algorithmic problems used in this study. Implications of the findings are discussed.

QUANTUM-CHEMICAL CONCEPTS: ARE THEY SUITABLE FOR SECONDARY STUDENTS?

Quantum-chemical theories of atomic and molecular structure are now part of the upper secondary curriculum in many countries, despite the fact that many educators are against their use in basic chemistry courses. In this paper, we first summarise the main findings of previous work on chemistry students’ knowledge and understanding of atomic orbitals, molecular orbitals and related concepts. We then report results of a study with twelfth-grade Greek students. A test was used that required critical thinking, and aimed to find whether students had acquired a deep understanding of the relevant concepts. The findings indicate that such understanding was missing from most students. Students did not have a clear understanding of orbitals, and especially their probabilistic rather than deterministic nature; for many, the orbitals represent a definite, well-bounded space; they did not realise the approximate nature of atomic orbitals for many-electron atoms; the inadequacy of the carbon-atom, ground-state, electron configuration to account for its valency of four was not evident. Implications for instruction and the curricula are discussed. [Chem. Educ. Res. Pract. Eur.: 2002, 3, 129-144]

Dimensional analysis and predictive models in problem solving

Dimensional analysis is used for the determination of the information‐processing demand (M‐demand) of a problem. A simple predictive model for multi‐step problems is proposed, and its predictions are checked against actual data. It is found that this model is successful in some cases, and unsuccessful in others even in cases of an M‐demand of 2. The effect of various psychological measures of the solvers is examined. A major predictive model for problem solving in science education is the working‐memory overload hypothesis of Johnstone and El‐Banna. This model is based on the working‐memory theory, as well as on Pascual‐Leones M‐space theory, and predicts that a subject will not be successful in solving a problem, unless the problem has an M‐demand which is less or equal to the subjects M‐capacity. Mechanisms that may block the solution or that may lead to violation of the model are examined, and some necessary conditions for its successful application are discussed in the light of research data.

Conceptual understanding versus algorithmic problem solving: Further evidence from a national chemistry examination

Following our previous paper (Chem. Educator, 2004, 9, 398-405), we analyze further the results of a national examination from the perspective of conceptual learning versus algorithmic problem solving. Detailed achievement data were studied for a sample of 499 eleventh-grade students (age about 17), who were following various branches or streams leading to all kinds of higher-education studies in Greece (the ”Positive‘, the ”Theoretical‘, and the ”Technological‘ Branches). Using qualitative criteria, we distinguished the questions into: (i) simple knowledge-recall, (ii) conceptual, and (iii) well-practiced (algorithmic), stoichiometric, exercises. The latter could further be divided into simple and more demanding ones. As in the previous study, this categorization was also supported by statistical principal component analysis, but this time a marginal structure was extracted, because (possibly) of the limited number and the low difficulty of the postulated conceptual questions. The interest of the study lies mainly in the comparison among the different branches, with the students of the Positive Branch demonstrating the highest mean scores. In addition, students‘ thinking was categorized according to Nakhleh‘s scheme. The Positive Branch had the highest number of students with algorithmic and with conceptual ability, but all branches had about equal share of students high only in conceptual ability. [Chem. Educ. Res. Pract., 2005, 6 (2), 104-118]

ANALOGIES IN CHEMISTRY TEACHING AS A MEANS OF ATTAINMENT OF COGNITIVE AND AFFECTIVE OBJECTIVES: A LONGITUDINAL STUDY IN A NATURALISTIC SETTING, USING ANALOGIES WITH A STRONG SOCIAL CONTENT

A longitudinal study of the use of chemical analogies and their effect on cognitive and affective factors of tenth- and eleventh-grade Greek students in a naturalistic setting is reported. Attention was paid to the structural correspondence between the analogue and the target. Regarding the analogue domain, emphasis was placed on using analogies with a strong and familiar social context. An experimental-control group design was adopted. Although it is difficult to separate the direct effect of the analogies from the social relevance and the enjoyment factors, our findings from questions set immediately after the introduction of each analogy, as well as from final examinations, provide evidence for the possible usefulness of the long-term use of analogies in the teaching of chemistry. Gender was found to make no difference. Analogies can be more effective for lower cognitive development students. A positive affective effect to most students was also found. Both developmental level and motivational trait play a definitive role, with the concrete students on the one hand, and the curious students on the other found to be more favourably disposed to this teaching strategy. Finally, recommendations for the proper and effective use of analogies in chemistry teaching are made. [Chem. Educ. Res. Pract.: 2004, 5, 33-50]

Conceptual versus algorithmic learning in high school chemistry: the case of basic quantum chemical concepts. Part 2. Students’ common errors, misconceptions and difficulties in understanding

Part 2 of the findings are presented of a quantitative study (n = 125) on basic quantum chemical concepts taught at twelfth grade (age 17-18 years) in Greece. A paper-and-pencil test of fourteen questions was used that were of two kinds: five questions that tested recall of knowledge or application of algorithmic procedures (type-A questions); plus nine questions that required conceptual understanding and/or critical thinking (type-C questions). As a rule, performance in type-A questions was relatively high while in the type-C questions it was much lower. Unacceptable performance in type-A questions was mainly caused by the application of a wrong algorithm or by partial answers. Analysis of the individual type-C questions led to the identification of common errors, misconceptions and difficulties in understanding. The Bohr model and the language of the old quantum theory featured prominently in the answers of many students, while other students were holding hybrid models, mixing the planetary with the quantum-mechanical model. Finally, suggestions for improved instruction and curricula are made.

Learning at the Macro Level: The Role of Practical Work

Contact with concrete examples of substances, their reactions and other properties, through the laboratory and other practical activities, is an integral part of chemical education. In this chapter, attention is paid to alternatives to the expository instruction, which has been criticized for placing little emphasis on thinking. Consideration is given to inquiry and project-based laboratories, problem solving, context-based approaches and student cooperative practical activities. Central to laboratory work is the proper observation of phenomena. Content knowledge is crucial for the proper interpretation of observations. On the other hand, failure by students to notice or record all observations, as well as overloading of working memory are main problems. Methods are discussed for directing students’ attention to the important observational stimuli in experiments; demonstrations are particularly helpful in this. Concrete experiences may be a prerequisite for a conceptual understanding of chemistry, but this understanding is eventually provided through the submicroscopic and symbolic levels. Connection of the macro level with the other two levels is an integral but difficult task. Ways to achieve the desired macro to submicro and symbolic transition are given consideration; history of science can be of great value here. The chapter concludes with some future perspectives for practical work.

CHEMICAL PHENOMENA VERSUS CHEMICAL REACTIONS: DO STUDENTS MAKE THE CONNECTION?

In this work, we examine whether tenth-grade high school students (N = 197, age 15- 16) as well as first-year university chemistry students (N = 77, age 18-19) can make the connection between chemical reactions and chemical phenomena. We used nineteen physical and chemical phenomena, and asked the students at one stage to distinguish physical from chemical phenomena, and at another stage to state in which cases one or more reactions occur. Students can be categorised into two distinct groups. One group includes those who do not always identify chemical phenomena with reaction(s), while the other group includes those who are successful in that distinction. Further, the students of the first group can be divided into two subgroups: (a) those who perform better in identifying the chemical phenomena; (b) those who perform better in identifying the reactions. A differentiation of chemical changes into natural and man-caused processes seems to be operating, at least with Greek students. On the other hand, students may be intuitively viewing chemical reactions as fairly simple processes, which can be expressed by means of chemical equations. Finally, it might be preferable to group (i) changes of physical state and phase, and (ii) solutions, in a separate category (physicochemical changes). [Chem. Educ. Res. Pract.: 2003, 4, 31-43]