高中化学教科书中“潜台词”的研究*

以人教版高中《化学1》《化学2》为研究对象,将化学教科书中“潜台词”分为文字中的“潜台词”、表格中的“潜台词”、插图中的“潜台词”3类,对教科书中“潜台词”的作用与功能、类型与呈现知识的方式进行了说明与分析。     

高中化学“乙酸乙酯的性质和制法”的项目式教学*——乙酸乙酯合成方法改进实验探究

以乙酸乙酯制备方法改进为目标,通过“分析直接酯化法的缺点,设计新合成方法” “探索改进实验方案” “总结汇报,分析实验方案的适用情境”等3个任务,使学生加深理解有机化学基本反应类型和认识工业生产的适用条件,理解有机化学与生产实际之间的联系,在探究过程中培养学生的信息处理能力、科学探究精神以及“科学态度与社会责任”的化学学科核心素养。     

化学课堂探究教学“制订计划”的评价

为了解化学课堂探究教学“制订计划”的有效性,在课堂观察与分析的基础上,提出化学课堂探究教学“制订计划”系统分析量表,并结合具体化学课堂探究教学,从计划制订的主体、计划制订的过程、计划内容本身等3个方面解析了“制订计划”环节。结果启示：化学课堂探究教学“制订计划”系统分析量表能科学有效地指导化学课堂探究教学,特别是其“制订计划”的设计、实施与评价。     

在解密“骗局”中推广化学科普知识*

“骗局”中也蕴含着丰富的化学知识。高校科普工作者可以在解密这些“骗局”中,推广化学科普知识。围绕5W 模式--“谁来科普”“要科普给谁”“如何科普”“科普什么”和“科普效果如何”等5个问题,尝试建立一种在解密“骗局”中推广化学科普知识的新思路。具体为:以青少年和老年人为重点科普对象,构建“老师+学生”共同实施、现场演示与讲解并重、新旧媒体联合传播、“效果指标体系”评价的科普模式,实现精准化学科普的目的。     

“三全育人”视阈下高校学科导论课程育人路径研究——“化学与社会”课程的问卷调研

以吉林大学化学学院开设的“化学与社会”课程为例,介绍学科导论课程“三全育人”初衷,探究学科导论课程“三全育人”路径。坚持内容为王,挖掘育人资源,创新教学方式,以期将思想政治工作融入学科导论课程各环节,助力“三全育人”综合改革。     

基于模型建构的“初中化学用语”教学*——从知识传递走向深度学习

通过化学用语认识模型的建构,彰显其教学功能价值,为内隐的“心智模型”与外显的“符号模型”之间建立可能的联系和发展。运用“联想与建构”“迁移与体验”“本质与变化”等教学策略,实现化学用语的教学从内容传递走向深度学习。     

“二氧化碳的性质及其转化”的项目式教学——探寻二氧化碳的工业捕集方案

以探寻二氧化碳的工业捕集方案为项目主题,开展初中化学二氧化碳的性质及其转化的教学。学生通过“建立价类二维模型并设计二氧化碳的理想转化路径”“实验探究二氧化碳的实际转化”“解决二氧化碳的工业转化”等3个项目子任务理解了物质“组成、性质、变化”之间的关系,运用手持技术数字化实验探究了二氧化碳在不同碱溶液中的吸收效率,发展了实验探究能力,构建了物质转化在化工生产领域的认知模型,提高了思维迁移的能力。从“碳捕集”到“碳利用”的进阶解决问题模式,有利于学生化学学科核心素养的内化。     

基于真实问题情境的化学活动课设计*——以“氧化铁与酸的反应”为例

基于联系生活实际的真实问题情境,设计化学活动课,让学生在探究“可乐可以除铁锈”本质原因的过程中学习“氧化铁与酸的反应”,从而发展化学学科核心素养,提高解决实际问题的能力。     

“证据推理”在高考化学试题(全国卷)中的考查特点*

基于《普通高中化学课程标准(2017年版2020年修订)》提出的化学学科核心素养中“证据推理”的内涵及相关研究,将“证据推理”化学学科核心素养进一步解构为 “证据解读”“证据与结论的关系”“证据评估”等3个要素,并将证据按其呈现形式划分为反应机理、实验数据、工艺流程和实验方案等4种类型,在此基础上构建了“证据推理”视角下的试题分析框架,并以近5年高考化学试题(全国卷)为研究对象,总结其考查特点与规律,进而为改进化学教学提出相关建议。     

基于“教学评一体化”的化学探究活动一般思路方法建构*——以“物质的分离与提纯”复习课为例

针对学生面对化学实验探究问题无从下手的情况,以物质的分离与提纯这一类探究实验为例,通过“教学评一体化”的教学模式引导学生建立解决“物质分离与提纯”探究实验的一般思路方法。     

Preferential Site Occupation in the Quasi‐Ternary Channel Compounds TlCr5S8–ySey (1 ≤ y ≤ 7) Introducing Anisotropic Variations of Interatomic Interactions: A Systematical Study of their Crystal Structures

The results of single crystal X‐ray investigations of the quasi‐ternary channel compounds TlCr₅S_8–ySe_y (1 ≤ y ≤ 7) show a linear increase of the unit cell volume with increasing Se content as expected for a solid solution. The successive occupation of the four distinct chalcogene sites by Se, however occurs in a nonlinear way. During the substitution the two sites X1 and X2 are strongly preferred by the Se atoms. For site X3 no significant preference is observed and site X4 is clearly less favoured by the Se atoms. This unusual behaviour can be interpreted on the basis of the different polarizabilities of the constituting atoms. The occupation of X1 and X2 by Se gives the strongest covalent bonding interactions, especially between Tl and Se thus being the driving force for the high preference of Se for these two sites. The preferential occupation of the four crystallographically independent chalcogene sites leads to an unexpected and spectacular dependence of the unit cell parameters and of the interatomic distances as function of the Se content. The a axis shows a negative deviation from linearity, whereas the c axis exhibits a positive one. The monoclinic angle β passes a maximum at y = 5, and finally drops to a value comparable with that obtained for the pure sulfide. A detailed analysis demonstrates that the series can be divided into the two different regions 0 ≤ y ≤ 4 and 5 ≤ y ≤ 8, both characterized by a linear variation of the lattice parameters as well as of the interatomic distances.     

Occupation numbers for atomic shells in direct space bounded by the maxima of the one‐electron potential

Atomic shells defined as wells of the one‐electron potential $\nabla^{2}\sqrt{\rho}/2\sqrt{\rho}$ bounded by successive maxima of this electron density function give reasonable electron numbers for the occupation of shells with empty d orbitals. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 83: 324–331, 2001     

Asymptotic Behaviour of the Pauli Potential for a Perfectly Screened Charge embedded in an Almost Degenerate Dense Plasma

Abstract

The asymptotic behaviour of the Pauli potential is established at zero and elevated temperatures for a perfectly screened charge embedded in jellium.     

Selective substitution of vanadium for molybdenum in Sr2(Fe1−xVx)MoO6 double perovskites

The crystal and magnetic structures of Sr₂(Fe_1−xV_x)MoO₆ (0.03?x?0.1) compounds are refined by alternately using X-ray powder diffraction (XRD) and neutron powder diffraction (NPD) data collected at room temperature. The refinement results reveal that the V atoms selectively occupy the Mo sites instead of the Fe sites for x?0.1. The 3d/4d cation ordering decreases with the increase of the V content. Slight distortions in the lattice and metal octahedra are shown at 300 K, and the distortions increase at 4 K. The magnetic structure at 4 K can be modeled equally well with the moments aligning along [001], [110] or [111] directions. The total moments derived from the NPD data for the [110] and [111] direction models agree well with the magnetic measurements, whereas the [001] model leads to a smaller total moment. Bond valence analysis indicates that Sr ions are properly located in the structure and Mo ions are compatible with both the Fe sites and the Mo sites. The electronic effects are suggested to be responsible for the selective occupation of the V on the Mo sites due to the different distortions of the FeO₆ and MoO₆ octahedra.     

New Ternary Compounds MxTa11−xGe8 (M=Ti, Zr, Hf): Structure and Stabilization

The title compounds M_xTa_11−xGe₈ (M=Ti, Zr, Hf) were prepared from the pure elements by arc-melting and subsequent induction heating at temperatures between 1200°C and 1400°C. X-ray powder diffraction studies of the samples were performed using the Guinier technique and the respective powder patterns were refined with a structure model based on the orthorhombic Cr₁₁Ge₈-structure type (oP76, Pnma). The homogeneity ranges of the compounds were determined to be 0.9<x<1.3 (M=Ti), 0.7<x<1.3 (M=Zr) and 0.7<x<2.4> (M=Hf) by means of electron probe microanalysis. Chemical bonding, electronic structure and site preferences are discussed based on extended Hückel calculations performed on hypothetical binary Ta₁₁Ge₈.     

Origin of the chemical shift in X‐ray absorption near‐edge spectroscopy at the Mn K‐edge in manganese oxide compounds

The absorption edge in Mn K‐edge X‐ray absorption spectra of manganese oxide compounds shows a shift of several electronvolts in going from MnO through LaMnO₃ to CaMnO₃. On the other hand, in X‐ray photoelectron spectra much smaller shifts are observed. To identify the mechanisms that cause the observed chemical shifts, 1s ionization as well as 1s → “4p” transition energies have been determined by electronic structure calculations on embedded Mn ions and embedded MnO₆ clusters. Systematic variation of the cluster geometry and the cluster embedding showed that the chemical shifts are predominantly determined by two effects: the changes in the Mn 3d occupation and the changes in the Madelung potential. The large chemical shift in the 1s → 4p transition energies between different materials occurs because the two effects do not compensate each other. The chemical shifts obtained for the embedded MnO₆ clusters agree reasonably with the experimental shifts. The small sensitivity to the material observed for the Mn 1s ionization energies is explained by the near cancellation of the effects of the Madelung potential and the 3d occupation of the Mn ion. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2003     

Atomic shells from the electron localizability in momentum space

The electron localizability indicator in momentum space is proposed as a functional of the same‐spin momentum pair density. This functional yields a discrete distribution of values, which are proportional to the charge needed to form a fixed very small fraction of a same‐spin electron pair. It resolves all atomic shells for the examined atoms (Li–Kr) with reasonable occupation numbers, especially in the valence region. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006     

Prediction and assignment of site occupation and energy levels for Pb ions in crystal hosts

The environmental factor h_e of the host was calculated quantitatively in Pb²⁺-doped 23 compounds based on the dielectric theory of chemical bond for complex crystals. The relationship between the A band energy E_A of Pb²⁺ and the environmental factor h_e was intensively studied. The results indicate that E_A of Pb²⁺ decreases linearly with increasing of h_e. A linear model was proposed which allows us to correctly predict and assign the site occupations and the position of A band for Pb²⁺-doped compounds if the crystal structure and the refraction index were known. Applied to SrGa₂O₄:Pb²⁺, CaAl₂B₂O₇:Pb²⁺ and SrAl₂B₂O₇:Pb²⁺, the theoretical predictions are in very good agreement with the experimental data. In SrGa₂O₄:Pb²⁺, the excitation spectrum of Pb²⁺ from two different cation sites was identified: the higher energy band of A (265 nm) from the site of Sr2, and the lower ones (280 nm) from the site of Sr1.     

The EC4 European Register for Clinical Chemists in relation to quality aspects

 The European Register for Clinical Chemists is founded and guarded by the European Communities Confederation of Clinical Chemistry (EC4). This register fits the current mind set of harmonization and globalization of occupations within the European Community. But in addition it enables and serves the continuing quest for quality assessment and improvement within the field of laboratory medicine. The content and position of clinical chemists in the European Union is described and the European Register outlined. Received: 10 July 2000 / Accepted: 20 July 2000     

Relation between the Slater–Kohn–Sham orbitals generated by the one-body potential V(r) of DFT and the Löwdin natural orbitals for inhomogeneous electron liquids

The Löwdin natural orbitals (NO) are defined as those orbitals which bring the first-order density matrix of a correlated electron assembly into diagonal form. Another one-particle density matrix with the same diagonal elements is the single-particle idempotent Dirac density matrix generated by the one-body potential of density functional theory. Here, we compare the off diagonal form of γ expanded in terms of the Slater–Kohn–Sham (SKS) orbitals generated by V(r) with the NO expansion of Löwdin for general inhomogeneous electron liquids. In particular, the equation of motion of the correlated γ is corrected from that of γ _s , both now containing the one-body potential V(r). To illustrate the theory presented here, we first construct an approximate, albeit accurate, correlated 1DM for the ground state of the He atom and display connections between the resulting NOs and the SKS orbitals. The second example we discuss, but now quite briefly, is that of the inhomogeneous electron liquid in crystalline Si, where the NO expansion is available from the literature.