Rabbit-ears hybrids, VSEPR sterics, and other orbital anachronisms (original) (raw)
Related papers
Valence Bond and Molecular Orbital: Two Powerful Theories that Nicely Complement One Another
Journal of Chemical Education, 2021
Introductory chemistry textbooks often present valence bond (VB) theory as useful, but incorrect and inferior to molecular orbital (MO) theory, citing the electronic structure of O 2 and electron delocalization as evidence. Even texts that initially present the two theories on equal footing use language that biases students toward the MO approach. However, these "failures" of VB are really just misconceptions and/or misapplications of the theory. At their theoretical limits, both VB and MO are equivalent; they simply approach that limit from different sides. Certain concepts may be easier to grasp with one theory or the other so that having a commanding knowledge of both is extremely beneficial. However, presenting one theory as superior to the other suppresses the ability to look at a problem from both sides and is therefore detrimental to students and the whole of chemistry. It is time for VB and MO to be taught on equal footing like the complementary theories they are.
Molecules
This essay describes the successive births of valence bond (VB) theory during 1916–1931. The alternative molecular orbital (MO) theory was born in the late 1920s. The presence of two seemingly different descriptions of molecules by the two theories led to struggles between the main proponents, Linus Pauling and Robert Mulliken, and their supporters. Until the 1950s, VB theory was dominant, and then it was eclipsed by MO theory. The struggles will be discussed, as well as the new dawn of VB theory, and its future.
Wesleyan Journal of Research, 2018
Choice-based instructional strategies have been designed to teaching valence shell electron pair repulsion (VSEPR) theory pertaining to determination of geometry of non-transition metal based molecules. Choice-based instructional strategies convey multi method representation of the same content in front of the learners. Students select the best alternative oftheir own choice and level. Consequently an effective learning environment may be offered by the teachers. Engagement towards development of choice-based learning strategies enhances the creativity and pedagogical competencies among the teachers. The proposed strategies will help introductory chemistry beginner's quick determination of geometry of non-transition metal based molecules with appreciable accuracy. The efficacy of this proposed choice-based strategy has been justified by simple statistical measure.
CHEMISTRY, 2003
The research described in this paper is an investigation into the conceptions held about atomic orbitals, hybridization and related concepts by prospective chemistry teachers. The research was carried out with the participation of a total of 167 undergraduate students from two faculties of Balikesir University in Turkey. The subjects completed a diagnostic test by responding, in writing, to open-ended and multiple-choice questions about atomic orbitals and hybridization. Students' responses and explanations were analysed, and response categories were established. The results indicated that students in the field of chemistry had some misconceptions about atomic orbitals, hybridization and some other concepts related to hybridization. The atomic orbital concept is one of the most important prerequisite concepts in learning about hybridization. The effects of understanding the atomic orbital concept in learning about hybridization were also investigated. Finally, some suggestions were made for a more effective teaching approach to ensure better learning of the topic. [Chem.
Molecular orbital theory is a conceptual extension of the orbital model, which was so successfully applied to atomic structure. As was once playfully remarked, "a molecule is nothing more than an atom with more nuclei." This may be overly simplistic, but we do attempt, as far as possible, to exploit analogies with atomic structure. Our understanding of atomic orbitals began with the exact solutions of a prototype problem – the hydrogen atom. We will begin our study of homonuclear diatomic molecules beginning with another exactly solvable prototype, the hydrogen molecule-ion \(H_{2}^{+}\).
Bond electron pair: Its relevance and analysis from the quantum chemistry point of view
Journal of Computational Chemistry, 2007
This paper first comments on the surprisingly poor status that Quantum Chemistry has offered to the fantastic intuition of Lewis concerning the distribution of the electrons in the molecule. Then, it advocates in favor of a hierarchical description of the molecular wave-function, distinguishing the physics taking place in the valence space (in the bond and between the bonds), and the dynamical correlation effects. It is argued that the clearest pictures of the valence electronic population combine two localized views, namely the bond (and lone pair) Molecular Orbitals and the Valence Bond decomposition of the wave-function, preferably in the orthogonal version directly accessible from the complete active space self consistent field method. Such a reading of the wave function enables one to understand the work of the nondynamical correlation as an enhancement of the weight of the low-energy VB components, i.e. as a better compromise between the electronic delocalization and the energetic preferences of the atoms. It is suggested that regarding the bond building, the leading dynamical correlation effect may be the dynamical polarization phenomenon. It is shown that most correlation effects do not destroy the bond electron pairs and remain compatible with Lewis' vision. A certain number of free epistemological considerations have been introduced in the development of the argument. q