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从2003年起至今,北京师范大学化学教育研究团队围绕“原子结构与元素性质”主题开展了跨越初中、高中必修、高中选择性必修的模型建构教学探索,涉及原子的构成微粒及空间分布、核外电子的运动状态、核外电子的排布规律以及元素性质等不同子主题。在这些教学探索中,梳理和还原了科学家解决问题的过程,对科学家所做实验进行再现、模拟,依据科学家在基于实验证据建构原子结构模型时的推理论证过程设计并指导学生开展模型建构活动,使学生理解、评价或参与模型建构的过程,促进学生建模能力和科学本质观的形成与发展。 相似文献
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在高中必修阶段“原子结构 元素周期律”主题已有研究的基础上,将“位构性”系统模型与学科能力活动任务相结合,提出了本研究的理论框架,进行了单元整体的教学设计并实施。通过预设学生的表现水平,设计各课时的评价任务,过程性地诊断学生在各个课时中“位构性”模型建构与学科能力的发展水平,描述学生在本章学习过程中的发展变化,促进了学生“证据推理与模型认知”等核心素养的发展。最后,归纳出以“位构性”模型建构和学科能力发展的“原子结构 元素周期律”在教学实践中的有效策略。以期能够对日后开展“原子结构 元素周期律”主题的教学设计与实践能够提供参考和建议。 相似文献
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证据推理是学生以其经验为基础、问题为起点,根据教师提供的一个或几个学习材料(已知判断),得出目标概念(新判断)的深度思维过程。通过梳理和界定证据推理的概念、证据类型、证据推理过程及核心要素,建构出实验探究教学中以“问题、解释、假设、证据、推理、结论”为要素及其之间关系的证据推理线形模型和循环模型,以此分析视角及其框架对“离子反应”教学中证据推理的过程进行了分析,并基于证据推理的6要素得出培养学生证据推理能力的启示与建议,达到证据推理过程中基本思想方法的外显,落实证据推理与模型认知的化学学科核心素养,也为今后的教学实践提供核心推理思路及教学建议。 相似文献
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基于“素养为本”视角,以“原子晶体”的教学为例,对教学主题内容、教学现状及学情进行分析;以发展学生化学学科核心素养为主旨确定教学目标;以“微粒-微粒间的相互作用-物质的聚集状态-物质性质”的认识思路为主线,以“模型认知,建构概念-证据推理,归纳性质-微观探析,探究结构-科学史实,揭示价值”的任务型教学流程,达到落实并发展学生化学学科核心素养的目的。 相似文献
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有机融合学生生活中的经验与体验和化学学习中的认知与思维,可优化课堂进程,提高学习效率,让化学知识建构的过程同时成为化学学科核心素养发展提升的过程。在“铁及其化合物的应用”的教学中,以“笔·墨”为情境生成真实问题,在互动、探究、体验中整合物质性质,建构思维模型,并应用模型解决问题,发展科学探究、证据推理、模型认知等化学学科核心素养。 相似文献
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为了反映化学学科发展的特点和趋势,充分突显现代科学技术发展的新成就。以“三谱解析阿司匹林”的4个教学环节为例,着重阐述质谱、红外光谱、核磁共振氢谱在有机物分子结构探究教学中的运用策略,从而建构出探究有机物分子结构的一般模型,培养学生的证据推理与模型认知的化学核心素养。 相似文献
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Kerstin Schulze‐Matthi Jürgen Bendig Petra Neubauer Burkhard Ziemer 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(6):e257-e258
The bonding geometry of sulfur in the cations of the title compounds, C8H11S+·CF3SO3? and C13H13S+·CF3SO3?, respectively, is similar and is independent of the ratio of the Me/Ph substituents. As expected, in both cations, the S—Ph bonds are somewhat shorter than the S—Me bonds. In both crystal structures, the interaction between cations and anions is similar. 相似文献
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Ming‐Liang Tong Shao‐Liang Zheng Xiao‐Ming Chen 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):960-962
The title compound, poly[[diaquadibromocadmium‐μ‐(1,3,5,7‐tetraazatricyclo[3.3.1.13,7]decane‐N1:N5)‐aquacadmium‐di‐μ‐bromo‐aquacadmium‐μ‐(1,3,5,7‐tetraazatricyclo[3.3.1.13,7]decane‐N1:N5)‐di‐μ‐bromo] dihydrate], [Cd3Br6(C6H12N4)2(H2O)4]·2H2O, is made up of two‐dimensional neutral rectangular coordination layers. Each rectangular subunit is enclosed by a pair of Cd3(μ2‐Br)6(H2O)3 fragments and a pair of (μ2‐hmt)Cd(H2O)2Br2(μ2‐hmt) fragments as sides (hmt is hexamethylenetetramine). The unique CdII atom in the Cd2Br2 ring in the Cd3(μ2‐Br)6(H2O)3 fragment is in a slightly distorted octahedral CdNOBr4 geometry, surrounded by one hmt ligand [2.433 (5) Å], one aqua ligand [2.273 (4) Å] and four Br atoms [2.6409 (11)–3.0270 (14) Å]. The CdII atom in the (μ2‐hmt)Cd(H2O)2Br2(μ2‐hmt) fragment lies on an inversion center and is in a highly distorted octahedral CdN2O2Br2 geometry, surrounded by two trans‐related N atoms of two hmt ligands [2.479 (5) Å], two trans‐related aqua ligands [2.294 (4) Å] and two trans‐related Br atoms [2.6755 (12) Å]. Adjacent two‐dimensional coordination sheets are connected into a three‐dimensional network by hydrogen bonds involving lattice water molecules, and the aqua, bromo and hmt ligands belonging to different layers. 相似文献
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Y. Akishige H. Shigematsu T. Tojo H. Kawaji T. Atake 《Journal of Thermal Analysis and Calorimetry》2005,81(3):537-540
Summary Specific heats on the single crystals of Sr2Nb2O7, Sr2Ta2O7 and (Sr1-xBax)2Nb2O7 were measured in a wide temperature range of 2-600 K. Heat anomalies of a λ-type were observed at the incommensurate phase transition of TINC (=495 K) on Sr2Nb2O7 and at the super-lattice phase transition of TSL (=443 K) on Sr2Ta2O7; the transition enthalpies and the transition entropies were estimated. Furthermore, a small heat anomaly was observed at the low temperature ferroelectric phase transition of TLOW (=95 K) on Sr2Nb2O7. The transition temperature TLOW decreases with increasing Ba content x and it vanishes for samples of x>2%. 相似文献
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Russell G. Baughman Kenneth L. Martin Rajendra K. Singh James O. Stoffer 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(2):o103-o106
In 2,4‐dihydroxybenzaldehyde 2,4‐dinitrophenylhydrazone N,N‐dimethylformamide solvate {or 4‐[(2,4‐dinitrophenyl)hydrazonomethyl]benzene‐1,3‐diol N,N‐dimethylformamide solvate}, C13H10N4O6·C3H7NO, (X), 2,4‐dihydroxyacetophenone 2,4‐dinitrophenylhydrazone N,N‐dimethylformamide solvate (or 4‐{1‐[(2,4‐dinitrophenyl)hydrazono]ethyl}benzene‐1,3‐diol N,N‐dimethylformamide solvate), C14H12N4O6·C3H7NO, (XI), and 2,4‐dihydroxybenzophenone 2,4‐dinitrophenylhydrazone N,N‐dimethylacetamide solvate (or 4‐{[(2,4‐dinitrophenyl)hydrazono]phenylmethyl}benzene‐1,3‐diol N,N‐dimethylacetamide solvate), C19H14N4O6·C4H9NO, (XII), the molecules all lack a center of symmetry, crystallize in centrosymmetric space groups and have been observed to exhibit non‐linear optical activity. In each case, the hydrazone skeleton is fairly planar, facilitated by the presence of two intramolecular hydrogen bonds and some partial N—N double‐bond character. Each molecule is hydrogen bonded to one solvent molecule. 相似文献
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Hiroki Akutsu Jun‐ichi Yamada Shin'ichi Nakatsuji 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(8):o433-o434
The title compound, C24H20P+·C9H17NO5S−, consists of an organic monovalent cation and an organic monovalent anion, the latter being derived from the TEMPO radical (TEMPO is 2,2,6,6‐tetramethylpiperidin‐1‐oxyl). Two inversion‐related anions interact via two –O—H⃛O—S– hydrogen bonds, forming a dimer in which there are no short contacts between the spin centres (–N—O) of the TEMPO(OH)SO3− anions. Furthermore, no significant magnetic interaction is observed between the dimers because the dimer is surrounded by cations. These results are consistent with the paramagnetic behaviour of the title salt. 相似文献
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9,10‐Diphenyl‐9,10‐epidioxyanthracene and 9,10‐dihydro‐10,10‐dimethoxy‐9‐phenylanthracen‐9‐ol
Anwar Usman Hoong‐Kun Fun Yun Li Jian‐Hua Xu 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(6):o308-o310
9,10‐Diphenyl‐9,10‐epidioxyanthracene, C26H18O2, (I), was accidentally used in a photooxygenation reaction that produced 9,10‐dihydro‐10,10‐dimethoxy‐9‐phenylanthracen‐9‐ol, C22H20O3, (II). In both compounds, the phenyl rings are approximately orthogonal to the anthracene moiety. The conformation of the anthracene moiety differs as a result of substitution. Intramolecular C—H⃛O interactions in (I) form two approximately planar S(5) rings in each of the two crystallographically independent molecules. The packing of (I) and (II) consists of molecular dimers stabilized by C—H⃛O interactions and of molecular chains stabilized by O—H⃛O interactions, respectively. 相似文献
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L. Abbas L. Bih A. Nadiri Y. El Amraoui H. Khemakhem D. Mezzane 《Journal of Thermal Analysis and Calorimetry》2007,90(2):453-458
Thermal and chemical durability studies of the phosphate glasses belonging to the binary MoO3-P2O5 and the ternary K2O-MoO3-P2O5 systems are reported. The chemical resistant attack tests carried out on the free alkaline MoO3-P2O5 glasses show that the glass associated with the P/Mo ratio 2 has the high chemical durability. It shows also a high glass
transition temperature value. The above findings are interpreted in terms of the cross-link density of the glasses and the
strength of the M-O bonds (M=P, Mo).
The influence of K2O addition on the properties (density, T
g, durability) of this binary high water resistant glass is studied. It is found that the chemical durability along with the
other physical properties are reduced by the incroporation of K2O in the glass matrix. The results were explained by assuming the formation of non-bridging oxygens and weak bonds. The mechanism
of the dissolution of these glasses is proposed. 相似文献
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Summary We have fabricated glasses in the Bi-2223 HTc superconductor system with Bi2Sr2Ca2Cu3-xErxO10+ δ nominal composition, where x=0.5 and 1.0, by the glass-ceramic technique. Using an analysis developed for non-isothermal crystallization studies, information on some aspects of crystallization temperature and thermal properties has been obtained. The crystallization studies were made using DTA with several uniform rates. The calculations of crystallization activation energies, Ea, and the Avrami parameters, n, were made based on the non-isothermal kinetic theory of Kissinger and the Ozawa’s equations. The DTA data of the samples showed that the first crystallization temperature, Tx1, increases and the second crystallization temperature, Tx2, decreases by increasing the Er concentration. This suggests that the Er substitution had significant effect on the glassification of the BSCCO material due to change on the surface nucleation and increased ionic activities at high temperature region. The activation energy for crystallization, Ea, of the samples was also showed an increase at high Er concentration case. However, the Avrami parameter, n, decreased from 2.5 to 1.7 for x=0.5 and 1.0 samples, respectively. This suggests that the growth mechanism is diffusion-controlled and three-dimensional parabolic growth takes place near the first crystallization temperature. The oxidization rates and the activation barrier for oxygen out-diffusion process, E, was calculated using the TG data. It was found that the total mass gain in the x=0.5 sample is comparably smaller than that of the x=1.0 sample. This shows that the oxygen absorption of the x=1.0 sample is faster than the x=0.5 sample, leading to increase in the oxidization rate in the x=1.0 material. 相似文献
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John Nicolson Low George Ferguson James L. Wardell 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):e317-e317
In the title compound, [Sb(CH3)(C6H5)3]BF4, there are four independent cations and anions in the asymmetric unit. The geometry around the Sb atom is distorted tetrahedral, with Sb—C distances in the range 2.077 (4)–2.099 (10) Å and angles at the Sb atom in the range 103.3 (3)–119.0 (4)°. 相似文献