促进学生化学认识方式发展的“过程与方法”维度教学目标设计——基于对高中生化学概念发展水平的测查与思考

高中生化学概念发展水平测查结果表明,学生化学概念发展中存在2个问题:(1)认识角度尚待丰富;(2)认识水平尚需提高。当前课程改革实践过程中,概念教学"过程与方法"维度目标设计中存在一系列问题。将认识方式发展目标落实到具体内容的"过程与方法"维度教学目标当中,为解决学生概念发展过程中存在的2个问题及教师在教学目标设计过程中存在的问题提供了可行的途径。     

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。     

基于促进学生认识发展的“物质的量浓度”教学设计研究——“高端备课”化学核心内容教学问题及其解决策略研究之一

以学生在物质的量浓度及相关内容学习过程中认识发展障碍点为切入点,分析了物质的量浓度概念和"配制一定物质的量浓度溶液"实验在发展学生对溶液组成的认识和形成定量认识方式方面的功能与价值,在此基础上进行"以促进学生认识发展为本"的教学设计,并与"以具体知识剖解为本"的教学设计方案进行了对比研究,通过问卷调查和学生访谈对教学效果进行检测。     

在分析化学实验教学中渗透"量"的概念

分析化学实验教学中存在的主要问题是学生对"量"的概念认识不清晰并且不重视。本文结合教学实践,提出了注重细节教学和数据的读、写、算,采用问题法以及讨论法等措施,在分析化学实验教学中渗透"量"的概念,使学生正确理解"量"的概念,在实验中能做到该细则细,该粗则粗。     

化学学科核心素养引领下的水溶液大单元教学设计与实践*

通过新旧课标与教材的对比分析,确定水溶液主题的认识方式、大概念和教学目标,围绕教学目标选择合适的情境素材,以大概念统领单元教学,在真实问题的解决过程中发展学生认识水溶液的基本角度和思路,促进学生化学学科核心素养的发展。     

化学概念教学要关注学生的思维过程和认识发展——“混合物和纯净物”教学案例透视

化学概念是学生化学学习的重要内容。化学概念的教学不应只关注具体概念内涵的识记和辨析,而应关注学生的思维过程,教给学生科学加工的方法,使之成为认识物质及其变化的思想工具。本文以“混合物和纯净物”概念教学为例,对案例中的教学问题进行了多角度分析,并从了解学生已有的知识经验、明确学生化学概念学习水平和认识发展目标、创设经历思维过程的学习活动3个方面阐述了促进学生认识发展的概念教学设计思路。     

“元素化合价”意义建构教学设计

根据建构主义理论分析了"元素化合价"概念意义建构条件,并进行了元素化合价教学设计和教学实践研究,获得了理想的教学效果。研究结果表明:认识原子结合其他元素原子的能力,在此基础上提出用"价"概念去表达原子的这种能力,引导学生形成准确的"元素化合价"概念,学生书写化学式的能力迅速提高。     

以核心素养为导向的聚合反应工程教学探讨——以“理想混合反应器的热稳定性”为例

在核心素养理念下,以聚合反应工程教材中的"理想混合反应器的热稳定性"小节教学设计为例,挖掘工程学科教学过程中蕴含的教育价值。通过对热稳定性原理的解析、探讨,以及对工业中热稳定性实例的分析,引导学生以工程科学思维去认识原理性概念;以探讨问题为驱动,进行探究式学习,培养学生工程问题意识和实践应用能力;在课程教学过程中落实大学生核心素养的培养和发展。     

学科大概念统领下基于真实情境的“合成高分子”单元教学

通过新旧课标与教材的对比分析，在大概念的统领下，确定“合成高分子”的教学目标以及认识方式。以“结构决定性质，性质决定用途”大概念统领单元教学，围绕教学目标选择新冠疫情下的“防病毒口罩”为情境，在真实问题的解决过程中发展学生认识合成高分子的基本思路，促进学生化学学科核心素养的发展。     

促进学生有机物性质认识能力发展的“醇类”教学研究

以"有机化学基础"选修模块中醇类及相关内容的教学设计为研究对象,探讨了醇类知识对于促进学生以有机物性质认识能力为核心的有机化学认识素养发展的功能和价值,从促进学生有机物性质认识能力发展的角度设计并实施了凸显"结构分析-性质预测"的探究活动为主的醇类教学,通过问卷调查和对学生的访谈对教学效果进行检测,并进行了基于学生不同认识基础的"醇类"教学效果的对比研究,探研先期所学习的结构与性质关系以及反应类型等知识对于学生有机物性质认识能力发展的积极影响。     

“水上”(“on water”)有机反应

"水上"有机反应的发展是水相绿色合成反应研究领域中的一个突破。体系的非均相性质是"水上"反应的基本特征。水不仅是重要的绿色反应介质,在大多数"水上"有机反应中都能观察到水对反应的速度和选择性有明显的提升作用。采用"水上"反应的条件,可以使反应的规模扩大,有利于产物的分离、纯化。本文以反应的类型分类综述了近年来有关"水上"有机反应研究的进展,以及在绿色有机合成中的应用。     

营养化学课程翻转课堂的探索与实践

With its tailored learning content, flexible learning environment and directed teacher guidance, the flipped classroom in "nutrition chemistry" has effectively solved the problems of students' specialty, large number and limited time in the course of elective course. The teaching mode based on the cultivation of students' ability and the core of improving scientific literacy was constructed.     

"Dip-Pen" nanolithography on semiconductor surfaces

Dip-Pen Nanolithography (DPN) uses an AFM tip to deposit organic molecules through a meniscus onto an underlying substrate under ambient conditions. Thus far, the methodology has been developed exclusively for gold using alkyl or aryl thiols as inks. This study describes the first application of DPN to write organic patterns with sub-100 nm dimensions directly onto two different semiconductor surfaces: silicon and gallium arsenide. Using hexamethyldisilazane (HMDS) as the ink in the DPN procedure, we were able to utilize lateral force microscopy (LFM) images to differentiate between oxidized semiconductor surfaces and patterned areas with deposited monolayers of HMDS. The choice of the silazane ink is a critical component of the process since adsorbates such as trichlorosilanes are incompatible with the water meniscus and polymerize during ink deposition. This work provides insight into additional factors, such as temperature and adsorbate reactivity, that control the rate of the DPN process and paves the way for researchers to interface organic and biological structures generated via DPN with electronically important semiconductor substrates.     

发展“模型认知”素养的教学实践*——以“化学方程式”为例

模型认知是重要的思维方法。基于模型认知进行教学设计,能促使教师从关注知识转向关注核心素养,从而使教学活动有效地促进学生思维能力的发展。在对模型及模型认知理解的基础上,以典型的符号模型“化学方程式”为例,阐明了教学思路和教学活动与学科观念的关系,形成了发展学生模型认知核心素养的教学设计。     

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.     

Theoretical study on "multilayer" nitrogen cages

The relative stabilities of nonisomers are investigated. Twenty-two species of nitrogen cage molecules N(2n) (N6 (D(3h)), N8 (Oh), N10 (D(5h)), N12 (D(6h)), N12 (D(3d)), N16 (D(4d)), N18 (D(3h)), N20 (Ih), N24 (D(3d)), N24 (D(4h)), N24 (D(6d)), N30 (D(3h)), N30 (D(5h)), N32 (D(4d)), N36 (D(3d)), N40 (D(4h)), N42 (D(3h)), N48 (D(4d)), N48 (D(3d)), N54 (D(3h)), N56 (D(4h)), and N60 (D(3d))), which are divided into four sets, have been studied in detail. The geometries and varieties of energies are examined extensively, and NBO analysis and AIM analysis are applied to investigate the bonding properties of the cage molecules. The introducing of the concept of "layer" can well assist in explaining why one nonisomer molecule is more stable than another one. The results show that the lengths of bonds, on both sides of which are five-membered rings (referred to as pentagons), are the shortest and the orbital energies are the lowest. The nonlocalized electron numbers of orbitals, on at least one side of which is a triangle, are the greatest. Pentagons play a major role in the stability of a cage molecule, and the three-membered rings (referred to as triangles) play the second one. The layers in nitrogen cage molecules also contribute to the relative stabilities.     

Functionalization of single-walled carbon nanotubes "on water"

Single-walled carbon nanotubes (SWNTs) are exfoliated and functionalized into small bundles and individuals by vigorous stirring "on water" in the presence of a substituted aniline and an oxidizing agent. This is an example of an "on water" reaction that leads to functionalized SWNTs, and it represents a "green", or environmentally friendly, process. A variety of reaction conditions were explored. The products were analyzed with Raman, UV-vis-NIR, and X-ray photoelectron spectroscopies, atomic force and transmission electron microscopies, and thermogravimetric analysis.