基于模型建构的论证教学在化学概念学习中的应用*——以“原电池”概念学习为例

基于呈现批判反思提炼(PCRR)模式,提出了假设呈现批判反思提炼(HPCRR)模式,并以“原电池”概念学习为例,进行教学设计与教学实施。研究对象为广东省佛山市某校高二年级2个平行班的92名学生,其中实验组和对照组均为46人。从概念理解和学生对该教学模式的态度等2个方面调查了实施效果。结果显示,教学干预后,实验组学生的概念理解明显优于对照组,表明该教学模式能有效促进学生的概念理解,实现概念转变。实验组学生对该教学模式的接受度较高,持积极态度。     

促进学生认识发展的学科教学认识的构建——以“原电池”为例

阐释了学科教学认识和促进学生认识发展教学的基本内涵,在此基础上结合化学学科和“原电池”的内容特点,从有关“原电池”的学科知识、课程知识、学生理解的知识、教学策略及表征的知识等4个方面,论述了“原电池”主题的学科教学认识的构建。     

基于GR编码的学生论证活动过程分析——以“化学教学论实验”教学为例

论证教学是当前国际科学教育教学的热点领域。论文采用准实验设计,使用混合研究方法,在“化学教学论实验”课程中对学生进行了为期一学期的教学实践过程。实验组开展论证式教学的实践活动,并采用GR编码方式细致地分析学生科学论证活动的过程。研究结果表明,论证教学可以显著提高化学师范生的科学论证能力,并提高化学实验课程的学习兴趣。     

整合多重表征 促进概念深度理解——以“原电池”为例

有效整合多重表征,是促进学生科学概念深度理解的一种有效策略。本研究整合了科学教育领域中的3个多重表征框架的内容,对高中必修模块的“原电池”进行了教学设计。首先引导学生依次学习原电池的宏观装置、微观原理和电极符号,初步建构原电池概念,之后基于氢氧燃料电池关联表征,让学生建构原电池的装置原理二维模型图,理解原电池概念,最后依托生活中的纽扣电池应用二维模型图实现表征转换,解决实际问题,实现对原电池概念的深度理解。     

以实验和论证为杠杆撬动化学概念深度学习*——以“分子与原子”教学为例

以倡导“理解与批判、联系与构建、迁移与应用”的深度学习为理念,围绕“分子与原子的概念”比较教材与文献的设计思路,调整认知脉络,着力解决“概念学习过程中实验探究少,宏观现象进入微观分析的相关实验不匹配,忽略证据推理、变化观念与平衡思想核心素养”等不足。设计“3种形态的碘与淀粉的反应、H2O2溶液与品红反应、H2O2溶液的分解反应”3组实验,设置学生画分子模型、画H2O2分子分解的微观过程等活动,提炼“物质种类、分子种类、物质性质之间的关系是什么？你从实验中找到哪些证据支持观点？前2个单元的实验,还有哪些可作为论证的依据？”等问题,引发学生充分论证。“实验、活动、问题、论证”环环相扣,促成教学内容的有效结构化,通过化学概念的深度学习实现化学学科核心素养的发展。     

高中生对化学核心概念掌握情况的测查分析——以“电解质、离子反应、化学键”概念群为例

电解质、离子反应、化学键组成一个核心概念群,是学生掌握相关知识的重难点。对北京市普通高中370名高二学生的测查显示:(1)概念掌握的程度为:化学键<离子反应<电解质。(2)“电解质的概念”与“导电原理”“离子反应概念”“离子共存”的掌握程度存在显著相关;电离与离子反应概念的掌握程度显著相关;“导电原理”与“离子反应概念”“离子共存”“离子键与共价键综合辨析”的掌握程度显著相关。表明电解质的概念、导电原理的理解与掌握是概念体系中的重要纽带。(3)优秀、中等、学困3类学生在解决容易和较难2类概念的相关问题上差异最大,而中等难度上的差异相对较小。基于此,提出了相应的核心概念教学对策。     

游戏教学在化学概念复习上的运用——谁是卧底

以“谁是卧底”这个游戏为依托，基于金属及其化合物这个章节，采用实验组与对照组比较以及访谈研究，证明“谁是卧底”游戏在化学概念复习上的优势与特点。旨在为教师或者科研工作者在化学教学过程中遇到的类似问题提供一些值得参考的解决方案。     

素养导向的项目教学研究——以盐桥概念为例

以盐桥概念教学为项目,从“桥”的概念出发,根据桥的作用、桥的选择依据以及实际电池中桥的成分与功能设立了3个项目任务;从“盐”的概念出发,根据盐的种类与浓度对原电池电流的影响设立了4个项目任务。通过项目任务,把盐桥概念与实际生活中的电池关联起来,让学生学会运用实验方法解决问题,培养学生将理论知识与实际的工程技术整合的能力,以及跨学科知识整合与模型构建的能力。     

大学无机化学中“原电池”的启发探究式教学实践*

介绍了大学无机化学课堂中“原电池”部分的教学实践。通过启发-探究式教学模式,启发学生把常见的氧化还原反应,经过不断的设问和探究,最终设计成原电池,实现了通过原电池装置来证实氧化还原反应发生了电子传递的教学目的。学生在教师的启发下探究、分析、推导、创新和修正,使学生清晰地认识到知识的前后逻辑关系,对氧化还原反应概念、原电池装置有更深刻的理解,培养了学生的科学辩证思维能力。     

化学能转化成电能的实验设计

以常见的铜锌原电池反应为例,设计了一组对比实验装置,即化学反应装置与原电池装置。以化学反应装置中的能量变化为依据,展示了化学反应中释放出的能量具体形式为“热”与“功”;通过与原电池装置的比较,证明原电池实验装置中的“热”转化为了电能。     

Determination of the enthalpy of fusion of K<Subscript>3</Subscript>TaO<Subscript>2</Subscript>F<Subscript>4</Subscript> and KTaF<Subscript>6</Subscript>

Areas of fusion and crystallization peaks of K₃TaO₂F₄ and KTaF₆ were measured using the DSC mode of a high-temperature calorimeter (SETARAM 1800 K). On the basis of these quantities, considering the temperature dependence of the calorimeter sensitivity, values of the fusion enthalpy of K₃TaO₂F₄ at the fusion temperature of 1181 K of (43 ± 4) kJ mol⁻¹ and of KTaF₆ at the fusion temperature of 760 K of (8 ± 1) kJ mol⁻¹ were determined.     

Physicochemical foundations of synthesis of new ferromagnets from chalcopyrites A<Superscript>II</Superscript>B<Superscript>IV</Superscript>C<Stack><Subscript>2</Subscript><Superscript>V</Superscript></Stack>

The results of studying phase equilibria of ternary A^IIB^IVC^V systems have been reported. Physicochemical foundations have been developed for the synthesis of new ferromagnets with Curie temperatures above room temperature structurally compatible with basic semiconducting materials. Methods of synthesis and physicochemical properties of manganese-doped A^IIB^IVC₂^V ferromagnets have been described. The results of theoretical simulation of magnetic properties have been considered and basic approaches to the explanation of the emergence of ferromagnetism in A^IIB^IVC₂^V doped with 3d metals have been surveyed. The most promising ways to produce and study dilute magnetic semiconductors as spintronics materials have been presented.     

Determination of the enthalpy of fusion of K<Subscript>3</Subscript>NbO<Subscript>2</Subscript>F<Subscript>4</Subscript>

Areas of fusion and crystallization peaks of K₃NbO₂F₄ were measured using the DCS mode of a high-temperature calorimeter (SETARAM 1800 K). On the basis of these quantities, considering the temperature dependence of the calorimeter sensitivity, the value of the fusion enthalpy of K₃NbO₂F₄ of (98 ± 6) kJ mol⁻¹ was determined at the fusion temperature of 1257 K.     

Structure of Zn<Subscript>3</Subscript>P<Subscript>2</Subscript>

The structure of Z_n3P₂ (P 4₂/nmc, a = b = 8. 0785 Å, c = 11. 3966 Å) was solved and refined to R = 3. 2% in a precision X-ray diffraction experiment (λ-MoK _a, graphite monochromator on a primary beam, 27,496 reflections) . Interatomic distances and bond angles have been determined. The fcc lattice of the structure is built from phosphorus atoms, and the zinc atoms occupy 3/4 of all tetrahedral voids; the structure is described by two equivalent models where 1/4 occupied (by zinc atoms) and 1/4 vacant voids change places. The zinc atoms that occupy the voids following the diamond principle do not change places.Original Russian Text Copyright © 2004 by I. E. Zanin, K. B. Aleinikova, M. M. Afanasiev, and M. Yu. Antipin__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 889–892, September–October, 2004.     

Coefficients of thermal expansion of KPb<Subscript>2</Subscript>Cl<Subscript>5</Subscript> and RbPb<Subscript>2</Subscript>Br<Subscript>5</Subscript> crystals

The temperature dependence of unit cell parameters for monoclinic KPb₂Cl₅ and tetragonal RbPb₂Br₅ crystals was studied in the range of 100–298 K. Linear and volume thermal expansion coefficients were determined.     

2,4‐Di­nitro­phenyl­hydrazones of 2,4‐di­hydroxy­benz­aldehyde, 2,4‐di­hydroxy­aceto­phenone and 2,4‐di­hydroxy­benzo­phenone

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.     

Effect of SO<Subscript>2</Subscript> on chlorination of Bi<Subscript>2</Subscript>O<Subscript>3</Subscript> + Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> mixtures

The reaction of Bi₂O₃ + Fe₂O₃ mixtures with chlorine and SO₂ at 250–700°C is studied. At 300–500°C, the degree of bismuth chloride sublimation from the oxide mixture increases in the presence of SO₂. Chemical sublimation of FeCl₃ occurs after BiCl₃ is virtually completely recovered from the solid phase.     

Phase diagram of V<Subscript>2</Subscript>O<Subscript>5</Subscript>-MoO<Subscript>3</Subscript>-Ag<Subscript>2</Subscript>O system

The results concerning the synthesis, structure and thermal properties of V₂O₅-MoO₃-Ag₂O samples in the vanadium rich region of ternary system are presented in the form of quasi-binary phase diagrams in which at constant V₂O₅/MoO₃ molar ratios, equal 9:1, 7:3 and 1:1, the content of Ag₂O was variable. A new ternary phase isostructural with NaVMoO₆ has been detected in the investigated system.