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

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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 quantummechanical model. Finally, suggestions for improved instruction and curricula are made.

mentioning

confidence: 94%

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

Papaphotis¹,

Tsaparlis²

2008

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“…Previous research acknowledges that learning about orbital ideas is problematic both at college level and in the university (Cervellati and Perugini, 1981;Cros et al, 1986Cros et al, , 1988Jones, 1991;Mashhadi, 1994;Shiland, 1997;Tsaparlis, 1997. ) This was echoed in the present study (Taber, 1997(Taber, , 2002a.…”

Section: Introduction -The Significance Of Molecular Orbitalsmentioning

confidence: 99%

Compounding Quanta: Probing the Frontiers of Student Understanding of Molecular Orbitals

Taber

2002

College level students are expected to be able to make sense of, and explain, aspects of chemical bonding and structure in terms of molecular orbital concepts. The present paper derives from in-depth research into the thinking of a small sample of college chemistry students. This study in one UK college revealed the ways in which students found the orbital concept problematic. A previous paper ("Conceptualizing quanta: illuminating the ground state of student understanding of atomic orbitals") reports how these students struggled to make sense of atomic structure in orbital terms. The present paper considers the students' understanding of the molecular orbital concept. It is suggested that when learners are introduced to ideas about molecular orbitals before they have mastered ideas about atomic systems, then their learning difficulties may be 'compounded' in the more complex context. For example, it was found that students often identified the orbitals involved in two-centre bonds as atomic orbitals. Representations of delocalised bonds invoked various alternative interpretations: but were seldom conceptualised as implying poly-centred molecular orbitals. These findings suggest that students are not given sufficient time to construct acceptable models of atoms and molecules as 'quanticles'. [Chem. Educ. Res. Pract. Eur.: 2002, 3, 159-173] TABER 160 properties of substances in terms of the distinct properties of the molecules. Yet it is known that students find such explanations problematic (Lijnse, et al., 1990;Taber 2001aTaber , 2002b.Students' tend to find it difficult to develop these types of explanations even when the molecular level properties are familiar from macroscopic scale phenomena (e.g. the same electrostatic forces that allow a comb to attract small pieces of tissue also act at the molecular level). Yet many of the important features of the behaviour of matter at the scale of molecules, ions and electrons are not familiar from experience of the macroscopic world. These features might be classed as 'quantum properties'.It is not surprising that the 'weirdness' of quantum behaviour -what one Nobel prize winning physicist has called "the crazy ideas of quantum mechanics" (Feynman, 1985, p.1)proves to be an additional barrier to students learning to use the chemists' models of matter. The quantization of energy, angular momentum etc., and the wave-particle nature of entities such as electrons, are alien to students. For example, the 'spin' of electrons (m s =± 1 / 2 ) is intrinsic, and does not mean the electron is spinning. Electron spin is sometimes referred to as quantum-mechanical spin to emphasise that the term spin is here used by analogy with the everyday meaning.This paper, and its prequel (Taber 2002a), are concerned with learning about the properties of matter at scales where these quantum effects do become significant, where particles might be labelled 'quanticles'. The particle model (or kinetic theory) of matter is a quantum theory: i.e. it claims that matter is not continuous but comp...

“…In fact some authors argue that instructors for general or introductory level chemistry should concentrate their efforts on descriptive chemistry and materials chemistry (e.g., Bent, 1984;Gillespie et al, 1996a,b;Tsaparlis, 1997). This might be reasonable for undergraduates who do not intend advancing in chemistry, but really only serves to place emphasis on rote learning and is hardly challenging.…”

Section: Implications For Teaching and Learningmentioning

confidence: 99%

Mental Models in Chemistry: Senior Chemistry Students Mental Models of Chemical Bonding

Coll

Taylor

2002

ABSTRACT:In this paper we describe research into learners' mental models for chemical bonding. New Zealand senior secondary students, undergraduates and postgraduates' mental models for chemical bonding were probed using an interview protocol that included the use of a variety of common substances and focus cards that depicted model use in some way. The study found that the learners' mental models were simple and realist in nature, in contrast with the sophisticated and mathematically complex models they were exposed to during instruction. The learners drew upon some concepts from other models when their models proved inadequate to explain macroscopic events. [Chem. Educ. Res. Pract. Eur.: 2002, 3, 175-184]