Valence Shell Electron Research Articles

Examining the Electron Phase Transformation Theory in the Context of Atomic Structure

The shortcomings of the Rutherford atomic model can be eliminated by the suggested phase transformation of the electrons from point to non-revolving surface charge in the vicinity of the nucleus. The energy balance investigations of this atom model indicated that the stability of the surface charge valence electron shell is ensured by the one-dimensional Casimir effect. If this theoretical prediction is correct then the first ionization energies of the elements should correlate linearly to the inverse of atomic diameter. Classical physics approach, the electrostatic attraction of the nucleus and the repulsion of the surface charge electron shell result in an identical relationship. The problem with the classical physics approach is that it does not offer an adequate explanation for the photoelectric effect and the free electrons inside the metal. Therefore, classical electrostatics cannot be considered the right physical process responsible for the stability of the valence electron/s in neutral atoms. The derived theoretical relationship, between atomic diameter and ionization energy, was tested up to 86 elements of the periodic table. The correlation coefficient is 0.9187. The correlation is stronger for individual periods. The empirical relationship between the ionization energy and atomic radii is well known, resulting in the same correlation coefficients. However, the correlation to the atomic radii does not reproduce the theoretically derived constant multiplier, contrarily to the atomic diameter relationship. Thus, the first ionization energy is the function of the atomic diameter. The uncertainties in the reported atomic sizes are relatively high. Therefore, the correlation between theory and experiments should be considered as excellent. The theoretically derived relationship between the first ionization energy and atomic diameter is the consequence of the proposed phase transformation of the electron. Thus the detected strong correlation between theory and experiments adds further support to the proposed atomic structure.

PENGEMBANGAN MEDIA BERBASIS KOMPUTER UNTUK PEMBELAJARAN KIMIA KELAS XI PADA SEKOLAH MENENGAH ATAS

Difficulty learning abstract consepts in material forms of the molecule based on the theory of electron domain and molecular hybridization in the formation of simple covalent coumpounds involving electron is verry small in size. With conventional learning to use the media shaped balloons and images/charta make their experience misconceptions. Make use of computer assisted animations media adobeflash program. The program is able to help students discover and explore the concepts of learning materials to animate the process of formation of the molecules of the compound geometry. The program is easy to obtain and can be used on all computers. Material forms of molecules according to VSEPR theory (valence shell electron pair repulsion) and Hybridization theory contained in the computer based media is aimed at helping students learn to achieve mastery of core competencies which are already contained in the syllabus set by time. Products are developed in accordance with the educational technology area abstract include students in determining the geometry of the steps forming the molecules of the compound. The stages are carried out in the development of media, namely: design learning, create computer based animation media, validate products with product testing. Advice of expert material/content, media expert, design expert, and data from trials of the target group to be enter performance improvement products. Based on the results of the expert validation and testing of the target group can be concluded that the computer –based instructional media products on the molecular forms of material at Senior High School chemistry in particular at ninth grade IPA (Natural Sciences). With regard to these results the school, especially Senior High School 8 Batanghari media products in order to incorporate this learning into the school website that can be accessed by the wider media users for further development. Keyword: Development, Computer based Media, Molecular Forms.

Influence of the use of 3D printing technology for teaching chemistry in STEM disciplines

AbstractTeachers can create engaging learning environments in engineering courses through pedagogical innovation using Information and Communication Technologies (ICT). Introductory chemistry courses in Science, Technology, Engineering and Mathematics (STEM) disciplines typically include the study of molecular models and periodic properties, which are inherently visual concepts. Unfortunately, these concepts are often taught using two‐dimensional drawings, although three‐dimensional (3D) printing offers an engaging approach to learning chemistry in these disciplines. Undergraduate engineering students are provided with modelling software and a 3D printer, allowing them to construct 3D models of basic Valence Shell Electron Pair Repulsion theory shapes using polylactic acid. The results of this research showed that the average score of the students in the control group was lower than that of the students in the 3D technology group. This research has found that the learning curve for modelling and the time required for printing are high, limiting the practical application of this exercise in student laboratory classes. However, in an appropriate environment, 3D printing technology has the potential to be a valuable tool for teaching and learning molecular models and periodic properties of chemistry courses in STEM disciplines.

Study of electronic structure and optical transition properties of low-lying excited states of AuB molecules based on configuration interaction method

High-level configuration interaction method including the spin-orbit coupling is used to investigate the low-lying excited electronic states of AuB that is not reported experimentally. The electronic structure in our work is preformed through the three steps stated below. First of all, Hartree-Fock method is performed to compute the singlet-configuration wavefunction as the initial guess. Next, we generate a multi-reference wavefunction by using the state-averaged complete active space self-consistent field (SACASSCF). Finally, the wavefunctions from CASSCF are utilized as reference, the exact energy point values are calculated by the explicitly correlated dynamic multi-reference configuration interaction method (MRCI). The Davidson correction (+Q) is put forward to solve the size-consistence problem caused by the MRCI method. To ensure the accuracy, the spin-orbit effect and correlation for inner shell electrons and valence shell electrons are considered in our calculation. The potential energy curves of 12 Λ-S electronic states are obtained. According to the explicit potential energy curves, we calculate the spectroscopic constants through solving radial Schrödinger equation numerically. We analyze the influence of electronic state configuration on the dipole moment by using the variation of dipole moment with nuclear distance. The spin-orbit matrix elements for parts of low-lying exciting states are computed, and the relation between spin-orbit coupling and predissociation is discussed. The predissociation is analyzed by using the obtained spin-orbit matrix elements of the 4 Λ-S states which spilt into 12 Ω states. It indicates that due to the absence of the intersections between the curves of spin-orbit matrix elements related with the 4 low-lying Λ-S states, the predissociation for these low-lying exciting states will not occur. Finally, the properties of optical transition between the ground Ω state <inline-formula><tex-math id="M3">\begin{document}$ {\rm A}^{1}{{{\Pi}}}_{1} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20231347_M3.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20231347_M3.png"/></alternatives></inline-formula> and first excited Ω state <inline-formula><tex-math id="M4">\begin{document}$ {{\mathrm{X}}}^{1}{{{\Sigma }}}_{{0}^{+}} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20231347_M4.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20231347_M4.png"/></alternatives></inline-formula> are discussed in laser-cooling filed by analyzing the Franck-Condon factors and radiative lifetime. And the transition dipole moment is also calculated. But our results reveal that the AuB is not an ideal candidate for laser-cooling. In conclusion, this work is helpful in deepening the understanding of AuB, especially the structures of electronic states, interaction between excited states, and optical transition properties. All the data presented in this paper are openly available at <ext-link ext-link-type="uri" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.doi.org/10.57760/sciencedb.j00213.00009">https://www.doi.org/10.57760/sciencedb.j00213.00009</ext-link>.

Recent advances in the chemistry of isolable carbene analogues with group 13-15 elements.

Carbenes (R2C:), compounds with a divalent carbon atom containing only six valence shell electrons, have evolved into a broader class with the replacement of the carbene carbon or the RC moiety with main group elements, leading to the creation of main group carbene analogues. These analogues, mirroring the electronic structure of carbenes (a lone pair of electrons and an empty orbital), demonstrate unique reactivity. Over the last three decades, this area has seen substantial advancements, paralleling the innovations in carbene chemistry. Recent studies have revealed a spectrum of unique carbene analogues, such as monocoordinate aluminylenes, nitrenes, and bismuthinidenes, notable for their extraordinary properties and diverse reactivity, offering promising applications in small molecule activation. This review delves into the isolable main group carbene analogues that are in the forefront from 2010 and beyond, spanning elements from group 13 (B, Al, Ga, In, and Tl), group 14 (Si, Ge, Sn, and Pb) and group 15 (N, P, As, Sb, and Bi). Specifically, this review focuses on the potential amphiphilic species that possess both lone pairs of electrons and vacant orbitals. We detail their comprehensive synthesis and stabilization strategies, outlining the reactivity arising from their distinct structural characteristics.

Reconstructing perspectives: investigating how molecular geometry cards (MGCards) and molecular model building (MMB) disrupt students' alternative notions of molecular structure – a qualitative study

The range of abstract concepts encountered when learning chemistry and the inability of students to make connections between the macroscopic, sub-microscopic, and symbolic representations, used in chemistry teaching, are believed to be the main reasons for students’ difficulty when learning chemistry. Prediction and determination of molecular geometry using the theory of valence shell electron pair repulsion (VSEPR) is a sample of the abstract concept that is hard to understand by students who learn chemistry. Students may comprehend these ideas better if the learning process is supplemented with cutting-edge, interactive learning aids. To address the conceptual difficulties that students encounter when learning how to predict the shapes of molecules, a card game (MGCards) has been developed which is supported by simple molecular model building (MMB). The card game allows students to work through the steps required to predict the shape of a molecule in an engaging format. The student learning process is supported by feedback at all stages (if students make a mistake, they receive hints that will help them in the next step of the game). Action research with qualitative methods has been used to design, develop, and evaluate the MGCards. The MGCards and MMB were piloted at the University of Leicester with year one Natural Sciences students and modified based on the feedback received. Both MGCards and MMB were then used as part of the first-year chemistry education programme at Tanjungpura University in Indonesia. The findings of students’ answer analysis (pre- and post-test) in both cycles showed that students had a better understanding after learning with MGCards and MMB. The positive feedback for MGCards and MMB confirmed that these resources were effective in delivering an engaging learning experience. The results suggest that MGCards and MMB play a significant role in enhancing students’ understanding while also keeping them engaged.

Ligand-enforced geometric constraints and associated reactivity in p-block compounds.

The geometry at an element centre can generally be predicted based on the number of electron pairs around it using valence shell electron pair repulsion (VSEPR) theory. Strategies to distort p-block compounds away from these predicted geometries have gained considerable interest due to the unique structural outcomes, spectroscopic properties or reactivity patterns engendered by such distortion. This review presents an up-to-date group-wise summary of this exciting and rapidly growing field with a focus on understanding how the ligand employed unlocks structural features, which in turn influences the associated reactivity. Relevant geometrically constrained compounds from groups 13-16 are discussed, along with selected stoichiometric and catalytic reactions. Several areas for advancement in this field are also discussed. Collectively, this review advances the notion of geometric tuning as an important lever, alongside electronic and steric tuning, in controlling bonding and reactivity at p-block centres.

Relativistic effects on the chemistry of heavier elements: why not given proper importance in chemistry education at the undergraduate and postgraduate level?

Abstract Relativistic effects are important to understand the chemistry of heavier elements across the periodic table (PT). Three important relativistic effects are: contraction of s- and p-orbitals (direct relativistic effect), expansion of d- and f-orbitals (indirect relativistic effect) and spin–orbit (SO) coupling to split the p-, d- and f-orbitals. Each of these effects is approximately proportional to Z 2 (Z = atomic number) for the valence shell electrons in many electron atoms and consequently, these relativistic effects dominantly control the properties of the heavier elements (mainly the 6th and 7th period elements). These aspects are not given the proper importance in most of the inorganic chemistry text books and in chemistry education at the university level.

Ronald James Gillespie. 21 August 1924—26 February 2021

Ron Gillespie moved in 1958 from a lectureship at University College London to McMaster University, Hamilton, Canada, where he spent all his subsequent career. He was a distinguished inorganic chemist who made major discoveries in the fields of acids and super-acids, the generation and study of new inorganic species particularly polyatomic cations, the cations of noble gas compounds and the development of the Valence Shell Electron Pair Repulsion and the Ligand Close Packing models for understanding molecular structures. Ron was active in reforming the teaching of introductory chemistry, avoiding if possible descriptions that relied on thermodynamics or quantum mechanics, and instead presenting qualitative non-mathematical models.

Interlocking Toy Bricks Help Nursing Students “Handle” Valence Electrons, Molarity, Solubility, and More!

For decades, chemical modeling sets have allowed the user to manipulate atoms and bonds using plastic/wooden ball and stick materials. Here is a design for an interlocking toy brick modeling set in which the undergraduate nursing student can manipulate electrons during the simulated chemical bonding exercise. The author presents a teaching and learning activity/demonstration designed to help undergraduate nursing (BSN) students both visualize and physically manipulate (“handle”) abstract chemical education topics such as valence shell electrons and molarity (with manipulatives for solubility rules) of salts, acids, and bases in a chemistry for health professions didactic course, as an effort to increase comprehension of these chemical education topics. This learning tool was one in a series of newly coined “PERCEIVE” (Preparing Engaging Real-time Chemical Education Interactive and Visual Examples) chemical education demonstrations, where BSN students prepare engaging demonstrations, while working in groups. The preparation (building) step allows students to get a “handle” on how the chemistry concept works. Afterward the newly prepared demonstrations are utilized as examples for chemical education and chemistry in health topics─hence, the “PERCEIVE” acronym. This publication outlines: (i) Connections between Molarity and Solubility in modern healthcare practices, (ii) The method and materials for using interlocking toy bricks selected according to CPK color-scheme for modeling valence shell electrons (based on Bohr models), (iii) Solubility rules, (iv) Molarity (and calculations), and (v) Results from anonymous pre- and postqualitative student questionnaires. Student responses indicated a marked increase in the ability to calculate molarity in different volumes (1 L vs 500 mL) postdemonstration. Additional qualitative surveys were conducted, and the results highlighted more than 90% of 152 respondents endorsed the continued implementation of this demo in subsequent chemistry for health professions courses.

First-Principles Study of the Doping Effect in Half Delithiated LiNiO2 Cathodes

A systematic theoretical study of dopants in a half-delithiated lithium nickel oxide (Li0.5NiO2) cathode is performed to determine the preferred occupation sites, dopant ion migration, and suppression of oxygen evolution. Dopants considered include Li, B, Na, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Y, Zr, Nb, Mo, In, Sn, Sb, La, Ce, Ta, and W. For the nontransition metal dopants, the energy barrier governing dopant migration is correlated with the number of valence shell electrons so that it increases from left to right across a row of the periodic table. For these dopants, the energy barrier also decreases moving down a column of the periodic table. For transition metal dopants, the energy barrier depends on the number of unpaired valence electrons of the dopant, so that the energy barrier is maximum near the middle of a transition metal row. Oxygen stability is studied by calculating the gap between O-2p and Ni-3d band centers. Most dopants that prefer occupying octahedral sites in the transition metal layer bring higher oxygen stability. In particular, oxygen stability is enhanced mostly by Mo, Sb, and W doping.

The Teaching Blind Spot and Practice Optimization of Valence Shell Electron Pair Repulsion Theory

The Teaching Blind Spot and Practice Optimization of Valence Shell Electron Pair Repulsion Theory

Enhancement of Indonesian High School Student Conceptual Mastery on VSEPR Topic Using Virtual Simulation of Molecule Shapes: A Case Study of Quasi-Experimental Evidence

The Valence Shell Electron Pair Repulsion (VSEPR) is an essential topic for high school student’s fundamental understanding of 3D shapes of chemical compounds. Due to the spatial aspect of the topic, the students were forced to imagine the geometry of the molecule by predicting the free or bonded electron pair repulsion. Suitable learning media to accommodate those features should be precisely selected to help students properly understand the geometry of the molecule based on the VSEPR topic. This study compared the significant difference in the application of two media of animation video and interactive simulation toward the control and experimental groups, respectively, to enhance conceptual mastery of the VSEPR topic. This study was a statistical quasi-experiment study with two classes of control (animation video) and experimental (interactive simulation) groups. The results of the significant difference test of the groups showed that the distribution of the experimental and control groups was not normal (significantly different) and normal (not significantly different), respectively. Analysis results using Mann-Whitney for the non-parametric free two samples comparative test with a 95% confidence level showed that the application of virtual simulation on the experimental group impacted more in improving the conceptual mastery of the VSEPR topic. Furthermore, there was an identified significant improvement in sub-concepts of the VSEPR topic in binding pair, molecular shape, and electron repulsion. These findings could support the teachers in designing lesson plans for students to master the VSEPR topic.

Hints for a formal language inspired by Lewis structures

SummaryIn this work we elaborate on the idea of a formal theory for a limited but important part of structural chemistry, that described by Lewis’ methods and VSEPR (Valence Shell Electron Pair Repulsion). For this purpose, recursive functions and propositional functions are defined, that apply to formal expressions of the structure, based on a finite set of symbols. This approach allows for the expression of numerous questions of chemical interest. The formalization of basic structural chemistry based on Lewis/VSEPR method is potentially useful for the automation of the related procedures, but possibly also of some use as complementary material in teaching and as a heuristic tool in structural chemistry.

Investigation of Major Flavonoids from Artemisia argyi as a Potential COVID-19 Drug: Molecular Docking and DFT Calculations

Flavonoids from natural products are well-identified as potential antiviral agents in the treatment of SARS-CoV-2 (COVID-19) infection and related diseases. However, some major species of flavonoids from Chinese traditional folk medicine, such as of Artemisia argyi (A. argyi), have not been evaluated yet. Here, we choose five major flavonoids obtained from A. argyi, namely, Jaceosidin (1), Eupatilin (2), Apigenin (3), Eupafolin (4), and 5,6-Dihydroxy-7,3′,4′-trimethoxyflavone (5), compared to the well-studied Baicalein (6), as potential inhibitors analogs for COVID-19 by computational modeling strategies. The frontier molecular orbitals (FMOs), chemical reactivity descriptors, and electrostatic surface potential (ESP) were performed by density functional theory (DFT) calculations. Additionally, these flavonoids were docked on the main protease (PDB: 6LU7) of SARS-CoV-2 to evaluate the binding affinities. Computational analysis predicted that all of these compounds show a high affinity and might serve as potential inhibitors to SARS-CoV-2, among which compound (5) exhibits the least binding energy (−155.226 kcal/mol). The high binding affinity could be enhanced by increasing the electron repulsion due to the valence shell electron pair repulsion model (VSEPR). Consequently, the major flavonoids in Artemisia argyi have a significant ability to reduce the deterioration of COVID-19 in the terms of DFT calculations and molecular docking.

Vegetables for building molecular models

An exciting classroom activity involving the construction of molecular models and building hybrid orbitals is presented in this paper. Basic molecular geometries were built by connecting different types of vegetables using bamboo skewers. Vegetable of different shapes were used to describe the hybridization of atomic orbitals. This exercise is suitable for high school and undergraduate chemistry students. The activity helps students to apply Valence Shell Electron Pair Repulsion (VSEPR) theory to envisage the basic shapes of molecules and to conceptualize the hybridization of the atomic orbitals

Ligand-field regulated superalkali behavior of the aluminum-based clusters with distinct shell occupancy

Protecting clusters from coalescing by ligands has been universally adopted in the chemical synthesis of atomically precise clusters. Apart from the stabilization role, the effect of ligands on the electronic properties of cluster cores in constructing superatoms, however, has not been well understood. In this letter, a comprehensive theoretical study about the effect of an organic ligand, methylated N-heterocyclic carbene (C5N2H8), on the geometrical and electronic properties of the aluminum-based clusters XAl12 (X = Al, C and P) featuring different valence electron shells was conducted by utilizing the density functional theory (DFT) calculations. It was observed that the ligand can dramatically alter the electronic properties of these aluminum-based clusters while maintaining their structural stability. More intriguingly, different from classical superatom design strategies, the proposed ligation strategy was evidenced to possess the capability of remarkably reducing the ionization potentials (IP) of these clusters forming the ligated superalkalis, which is regardless of their shell occupancy. The charge transfer complex formed during the ligation process, which regulates the electronic spectrum through the electrostatic Coulomb potential, was suggested to be responsible for such an IP drop. The ligation strategy highlighted here may provide promising opportunities in realizing the superatom synthesis in the liquid phase.

Level Structure and Properties of Open f-Shell Elements

Open f-shell elements still constitute a great challenge for atomic theory owing to their (very) rich fine-structure and strong correlations among the valence-shell electrons. For these medium and heavy elements, many atomic properties are sensitive to the correlated motion of electrons and, hence, require large-scale computations in order to deal consistently with all relativistic, correlation and rearrangement contributions to the electron density. Often, different concepts and notations need to be combined for just classifying the low-lying level structure of these elements. With Jac, the Jena Atomic Calculator, we here provide a toolbox that helps to explore and deal with such elements with open d- and f-shell structures. Based on Dirac’s equation, Jac is suitable for almost all atoms and ions across the periodic table. As an example, we demonstrate how reasonably accurate computations can be performed for the low-lying level structure, transition probabilities and lifetimes for Th2+ ions with a 5f6d ground configuration. Other, and more complex, shell structures are supported as well, though often for a trade-off between the size and accuracy of the computations. Owing to its simple use, however, Jac supports both quick estimates and detailed case studies on open d- or f-shell elements.

Ionization energy and valence electron orbital binding energy of superheavy element Og(<i>Z</i> = 118) and its homologs

The ionization energy of the superheavy element Og (<i>Z</i> = 118) and its homolog elements Ar, Kr, Xe, Rn, and their ions are systematically calculated by using the GRASP2K program based on the multi-configuration Dirac-Hartree-Fock (MCDHF) method, taking into account relativistic effects, electron correlation effects between valence shell electrons, quantum electrodynamics effects, and Breit interaction. To reduce the uncertainty of the ionization energy derived from electron correlation effects which are not fully considered, the ionization potential of the superheavy element Og<sup>0–2+</sup> and its homolog element Rn<sup>0–2+</sup> are extrapolated by the extrapolation method. The ionization energy of extrapolated Rn<sup>0–5+</sup> and Og<sup>5+</sup> coincide well with experimental and other theoretical values. These results can be used to predict the unknown physical and chemical properties of the atoms and compounds of the superheavy element Og. In addition, the calculation results of the electron orbital binding energy of the atomic valence shell of the superheavy element Og and its homolog elements Ar, Kr, Xe, and Rn under relativistic and non-relativistic conditions show that owing to the relativistic effect, there occur strong orbital contraction phenomena in the 7s orbital and 7p<sub>1/2</sub> orbital and strong splitting phenomena in the 7p<sub>1/2 </sub> orbital and 7p<sub>3/2</sub> orbital of Og, which may cause the physical and chemical properties of the superheavy element Og to differ from those of other homologs.

Ionization energy and valence electron orbital binding energy of the superheavy element Og(Z=118) and its homologs

The ionization energy of the superheavy element Og (Z=118) and its homolog elements Ar, Kr, Xe, Rn, and their ions were systematically calculated using the GRASP2K program based on the multi-configuration Dirac-Hartree-Fock (MCDHF) method, taking into account relativistic effects, electron correlation effects between valence shell electrons (VV), quantum electrodynamics (QED) effects, and Breit interaction. To reduce the uncertainty of the ionization energy derived from electron correlation effects which are not fully considered, the ionization potential of the superheavy element Og<sup>0-2+</sup> and its homolog element Rn<sup>0-2+</sup> are extrapolated by the extrapolation method. The ionization energy of extrapolated Rn<sup>0-5+</sup> and Og<sup>5+</sup> coincides well with experimental and other theoretical values. These results can be used to predict the unknown physical and chemical properties of the atoms and compounds of the superheavy element Og. In addition, the calculation of the electron orbital binding energy of the atomic valence shell of the superheavy element Og and its homolog elements Ar, Kr, Xe, and Rn under relativistic and non-relativistic conditions shows that due to the relativistic effect, there is a strong orbital contraction phenomenon in the 7s and 7p<sub>1/2</sub> orbitals and a strong splitting phenomenon occurs in the 7p<sub>1/2</sub>and 7p<sub>3/2</sub> orbitals of Og, which may cause the physical and chemical properties of the superheavy element Og to be different from other homologs.