中学生“原子结构”相异构想的认知成因分析及转变策略

物质结构内容的抽象性导致学生产生大量的相异构想,影响着学生对化学概念的学习和深刻理解。通过整合国内外相关研究结果,从思维的视角分析了中学生“原子结构”相异构想产生的原因,并提出转变学生相异构想、促进概念理解的教学策略。     

高中学生化学概念掌握和问题表征程度关系的实证研究

本研究结合国内外有关化学概念教学的研究情况,对高中学生化学概念掌握和问题表征程度的关系进行了实证性的探索和研究。设计并在江苏省7所不同类型的学校进行了有关化学概念掌握的研究测试,同时选取优差学生进行有关化学问题的口语报告作业。研究结果表明：学生化学概念理解水平显著地影响着其解题时的表征程度。     

中学生对“溶液”概念理解的可视化表征及启示

学生概念理解的可视化表征可以通过学生的作图来展示,分析图示可以获取学生概念理解的更加深入的信息。梳理了国内外有关中学生对“溶液”概念理解的研究,集中对学生的作图进行分析,呈现了中学生对“溶液”概念理解的可视化表征。针对作图发现的学生概念理解的结果,提出了促进中学生“溶液”概念理解的教学启示。     

让铁器文物与历史说话*——“金属的电化学腐蚀与防护”教学

以铁器文物的防护为背景,在“金属的电化学腐蚀与防护”主题中,尝试将铁器文物与中学化学教学相结合,通过对不同环境中铁器文物腐蚀原理的探究,了解运用化学原理解释铁器文物保护的方法,使学生掌握金属的电化学腐蚀与防护知识,感受化学对人类的影响,促进学生化学学科核心素养的发展。     

厘清核心概念及其学习进程:分析教材的新视角——以中学化学“电化学基础”教学内容为例

以一线教师对人教版高中化学选修4《化学反应原理》教材的"化学电源"教学中关于学生认识发展的教学困惑为切入点,做了基于核心概念的中学化学"电化学基础"教学内容分析,并由此梳理出从初中化学到高中选修4学段学生对该内容的学习进程。以"化学电源"教学的再设计,说明厘清核心概念及其学习进程对促进学生认识发展的教学价值。     

国内"化学概念教学"研究新进展

以国内化学概念学习研究为主要内容，从3个方面分析了国内对化学概念学习的研究：(1)关于化学概念教学的经验性研究；(2)关于化学概念教学的理论性研究；(3)关于化学概念教学的现代研究。本文也简单分析了国外化学概念教学的研究，并且通过对比国内外化学概念教学的研究，得到了一些启示。     

以核心概念为本的“电解池”教学设计

通过梳理教材中电化学基础的知识结构及核心概念,并结合学生实际进行教学目标、教学方式、师生活动和问题情境等方面的教学设计。以人教版《化学反应原理》第四章第三节“电解池”第一课时的教学设计为例,说明以核心概念为本的教学设计可以促进学生对化学概念的理解,增强学生分析问题、解决问题的能力。     

国内外化学相异构想研究的进展与启示*

国内外有关化学学科的相异构想研究主要包括对学生相异构想进行诊断及其原因分析,以及开发有效的教学模式或策略对学生相异构想进行概念转变。通过对国内外相关研究现状的分析,为相异构想的后续研究提供思路。     

国内外化学教师PCK的实证研究述评

主要从PCK的测查、发展及其影响因素3个方面梳理国内外化学教师PCK的实证研究。综述表明：（1）这些研究侧重于对PCK多个组分及其关系的整体测查;（2）研究者主要采用外驱型与内驱型2种策略以发展化学教师的PCK;（3）影响化学教师PCK发展的因素主要包括其自身的教育背景、教学经验、反思、实践导师的指导等,同时学科知识与信念对PCK的影响也日益受到重视。基于国内外化学教师PCK研究趋势的对比,文末对我国化学教师PCK的实证研究以及化学师范生教育提供相应的建议。     

发展学生化学学科核心素养的课例研究——以“离子反应”为例

以高中化学“离子反应”概念教学为例,阐述了发展学生化学学科核心素养的课例研究思路和教学活动设计。围绕离子反应概念、离子方程式书写、离子反应发生条件等知识内容,挖掘教学内容与学科核心素养内涵的联系,创设真实且富有价值的问题情境,开设高水平的实验探究活动,注重微观分析过程,将离子反应概念的学习与从微观离子角度分析水溶液中反应的认识思路进行整合,力求发展学生的化学学科核心素养,帮助学生形成对“离子反应”概念的整体认识。     

"Decoking" of a "coked" zeolite catalyst in a glow discharge

'Decoking' of a 'coked' zeolite catalyst in a glow discharge in oxygen is investigated. The 'decoking' process involves reactions of atomic oxygen (O atoms) with 'coke' and yields gases such as CO, CO₂ as well as other gaseous products that could be easily pumped out.Three different modes of discharge were investigated including a static mode, a flowing-gas mode, and a periodic-purge mode where the oxygen and other gaseous products of the discharge were replaced by fresh O₂ gas after short but regular intervals of time. In some cases, additional heating was also used to provide base temperatures of the order of 100 °C to facilitate penetration of oxygen atoms into the inner layers and cages of the zeolite catalyst.This paper presents some results of spectroscopic analytical techniques used to monitor the atomization of oxygen, oxidation of 'coke', and to confirm the process of 'decoking'. More specifically, radiation emission on the 3 s ⁵S– 3p ⁵P transitions of O around 777.2–777.5 nm were selected for monitoring the atomization of O₂. On the other hand, X-ray photo-electron spectroscopy (XPS) was used to determine the amount of residual carbon and extent of 'decoking'. Furthermore, evolution of CO and CO₂ gases as a function of time was systematically monitored in real time. For CO, the 451.1 nm band head belonging to the B¹ - A¹ bands of the Angstrom system of the CO spectrum was used, while for CO₂, the band head at 353.4 nm belonging to the CO₂⁺ spectrum was used. The rates of evolution of CO and CO₂ were related to the rate of 'decoking' of the catalyst. It is noted that in the periodic-purge mode, about 63% of the total yield of CO from a given sample of the catalyst appears in the first 3-min exposure to discharge whereas it takes up to 15 min to remove nearly 94% of the removable carbon under our experimental conditions.     

Switching "on" and "off" the expression of chirality in peptide rotaxanes

The hydrogen-bond-directed synthesis, X-ray crystal structures, and optical properties of the first chiral peptide rotaxanes are reported. Collectively these systems provide the first examples of single molecular species where the expression of chirality in the form of a circular dichroism (CD) response can selectively be switched "on" or "off", and its magnitude altered, through controlling the interactions between mechanically interlocked submolecular components. The switching is achievable both thermally and through changes in the nature of the environment. Peptido[2]rotaxanes consisting of an intrinsically achiral benzylic amide macrocycle locked onto various chiral dipeptide (Gly-L-Ala, Gly-L-Leu, Gly-L-Met, Gly-L-Phe, and Gly-L-Pro) threads exhibit strong (10-20k deg cm(2) dmol(-1)) negative induced CD (theta;) values in nonpolar solvents (e.g. CHCl(3)), where the intramolecular hydrogen bonding between thread and macrocycle is maximized. In polar solvents (e.g., MeOH), where the intercomponent hydrogen bonding is weakened, or switched off completely, the elliptical polarization falls close to zero in some cases and can even be switched to large positive values in others. Importantly, the mechanism of generating the switchable CD response in the chiral peptide rotaxanes is also determined: a combination of semiempirical calculations and geometrical modeling using the continuous chirality measure (CCM) shows that the chirality is transmitted from the amino acid asymmetric center on the thread via the macrocycle to the C-terminal stopper of the rotaxane. This understanding could have important implications for other areas where chiral transmission from one chemical entity to another underpins a physical or chemical response, such as the seeding of supertwisted nematic liquid crystalline phases or asymmetric synthesis.     

让学习真实地发生——“厨房中的化学”教学解读

教学的艺术在于使教学事件和学习事件相匹配,从而促进学习自然真实地发生。从情境学习、建构主义、PISA视角、科学方法、情绪心理等5个角度入手,对"厨房中的化学"一课作了具体的教学解读:通过创设真实的情境、设计真实的问题、培养真正的能力、建构真切的体验、激发真情的投入等5种教学行为,有效地促进了学习的真实发生。     

试谈“集合”在化学教学中的运用

集合是数学和现代思维学中的一个重要概念,它与各学科有着广泛的联系,中学生在高一代数学中已系统学过集合的基本概念及其运用,在化学中引用集合概念描述物质的属性、概念的内涵和外延具有生动、严密、直观等优点,有利于培养学生逻辑思维能力和抽象思维能力,有利于激发和保持学生学习化学的兴趣。以下就谈谈集合在化学教学中的一些运用。     

基于现代信息技术的结构化学一维势箱理论和HMO法“翻转课堂”教学设计

In the article, we presented an instructional design of "Particle in One-Dimensional Box Theory" and "HMO Theory" application based on flipped classroom teaching. The students are instructed to use both "Particle in One-Dimensional Box Theory" and "HMO Theory" to solve the electronic structure of olefins and enhance their understanding of quantum mechanics theory via comparison of "Particle in One-Dimensional Box Theory" and "HMO Theory".     

A "renaissance" in radical trifluoromethylation

This Minireview highlights recent developments in radical trifluoromethylation reactions. The trifluoromethyl group belongs to the privileged moieties in medicinal chemistry. Many drugs and drug candidates contain a trifluoromethyl substituent. Also in agrochemicals, the CF(3) moiety often appears. The present article addresses the radical trifluoromethylation of alkenes and arenes mainly focussing on recent achievements. However, important earlier work in this field is also covered.     

"Electronic lock" in chromiumtricarbonyl complex of cycloheptatrienyltin

The fast sigmatropic [1,5]-Sn migration in cycloheptatrienyl(triphenyl)tin is effectively locked in the chromiumtricarbonyl complex. A much slower [1,3]-Sn + [1,2]-Cr diatropic rearrangement was detected by spin saturation transfer NMR.     

Direct complexometric determination of aluminium in "alzinoy"

A simple and precise method for the complexometric determination of aluminium in "Alzinoy" (a binary alloy of aluminium and zinc) is described. After dissolution of the sample in hydrochloric acid, aluminium, zinc and any lead and iron are complexed with excess of EDTA. The excess of EDTA is titrated with lead solution, with Xylenol Orange as indicator. Ammonium fluoride is then added to decompose the Al-EDTA complex, and the EDTA liberated is titrated with lead solution. Four samples can be analysed in about 45 min.