高中化学“次氯酸盐的性质”的项目式教学*——84消毒液的使用指南

以“84消毒液的使用指南”为主题,开展高中化学“次氯酸盐的性质”的教学。学生通过完成“一张图说清消毒剂”“探究84消毒液的漂白效果与酸碱性的关系”“探究84消毒液的漂白效果与光照的关系”“探究84消毒液的漂白效果与温度的关系”“84消毒液与酒精混合会有氯气吗”等5个项目任务,理解了次氯酸盐的性质及漂白原理,培养了学生的文献检索能力、实验探究能力以及发展了学生的高阶思维能力。将文献查阅与学生实验相结合,让学生在真实问题的解决中,完成次氯酸盐的性质等相关知识的内化,是顺利完成本项目教学的关键。     

基于模型认知的“价层电子对互斥理论”学习进阶设计*

遵循学生认知发展的客观规律,以及化学学科核心素养“模型认知”由低到高的水平划分,借助PhET互动仿真模型平台,通过虚拟的分子模型搭建和真实的分子构型对比,将“成键电子”“孤对电子”和“价层电子对”等抽象知识,融入认识模型、理解模型、运用模型和建构模型的递进式学习进阶设计中,在促进学生对互斥行为深度理解的同时,避免了虚拟可视化模型的过度类比可能导致的“相异构想”。     

初中化学“溶液”的项目式教学*——白砂糖的梦想之路

以“白砂糖的梦想之路”为项目学习主题,呈现了初中化学“溶液”的项目教学案例。基于棒棒糖的制作过程开发了系列学习任务,有助于学生在真实的问题情境中发展核心素养和构建灵活的知识基础。     

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。     

基于文献分析的“氧化还原反应”概念教学逻辑

以15篇有关“氧化还原反应”的课例研究文献为研究对象,基于内容分析法归纳出4种主要的教学逻辑：“分类标准直给型”“分类标准批判型”“反应本质揭示型”“知识演绎批判型”。从“知识是什么”“知识是如何被理解的”2个维度对4种教学逻辑进行评析,以反思氧化还原反应教学研究的发展及其局限。     

基于化学学科理解的教学——以“苯”为例

以“第一种人工合成染料苯胺紫”为素材创设情境,将煤、苯和染料苯胺紫等建立联系,由此引导学生探讨3个问题:“苯从哪里来”“如何确定苯的结构”及“如何解释苯的性质”,让学生在收获具体知识的同时,理解苯环结构的稳定性,了解苯的结构的研究历史背景以及苯环结构学说在有机化学发展史上的卓越作用。     

初中化学教学中培育社会责任素养*——以“燃料及其利用”复习教学为例

在分析“社会责任”素养内涵和研究现状的基础上,制订了初中化学“燃料及其利用”复习教学课的“社会责任”素养目标,并设计了以“秸秆综合利用的变迁”以及“历史悠久的薪柴燃料-使用方便的化石燃料-清洁环保的新型燃料”的燃料“进化史”为主线的教学流程。从“燃料及其利用”复习教学来看,初中化学教学可以通过真实情境、创新实验和有意义的学习经历等实践路径让学生获得“社会责任”体验,形成“社会责任”素养。     

发展学生化学学科核心素养的“化学能与电能”教学*——小车为什么会跑起来

“化学能与电能”是高中化学必修阶段的核心内容,是发展学生化学学科核心素养的重要知识载体。围绕“小车为什么会跑起来”的真实问题,利用铜锌原电池驱动小车的实验现象,引导学生分析原电池的工作原理,探究原电池的构成条件,充分发展学生的化学学科核心素养。     

基于“虚拟化学实验室”的在线课堂深度学习*—以“价层电子对互斥模型(VSEPR)”在线教学设计为例

在线课堂作为一种远程教育方式,往往会导致学生缺乏学习社区感。面对抽象的理论性知识,学生易陷入一种“离身”的困境。基于此,借助虚拟化学实验室,设计一堂“身临其境”“做中学”的价层电子对互斥模型课,实现“抽象内容具身认知化”“在线学习互动现实化”的在线课堂深度学习。     

以深度的科学探究促进初中生高阶思维能力发展*——以“酸和碱的中和反应”为例

针对学生在学习“酸和碱的中和反应”中普遍存在的“被动接受具体知识、缺失开展真实科学探究的思路、机械记忆中和反应规律、缺乏批判质疑精神及高阶思维能力不足”等倾向问题,设置了驱动性问题链协助学生搭建“情境问题”与“真实的科学探究”间的思路桥梁,在深度的科学探究中发展学生的发散性思维、有序思维、多角度分析问题、设计创造思维、逻辑严密的推理及评价反思等高阶思维能力。课堂教学中营造轻松、舒适的交流讨论环境,有益于学生之间碰撞出思维的火花、激发出创造的灵感。课堂观察表明,深度科学探究教学的实施,有效提升了学生的高阶思维能力及解决问题的能力。     

Di­methyl­phenyl­sulfonium tri­fluoro­methane­sulfonate and methyl­di­phenyl­sulfonium tri­fluoro­methane­sulfonate

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.     

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.     

Bis(μ‐hexa­methyl­enetetr­amine)­bis(aqua­di­bromo­cadmium)­di­aqua­di­bromo­cadmium dihydrate

The title compound, poly­[[di­aqua­di­bromo­cadmium‐μ‐(1,3,5,7‐tetra­aza­tri­cyclo[3.3.1.1^3,7]decane‐N¹:N⁵)‐aqua­cad­mium‐di‐μ‐bromo‐aqua­cadmium‐μ‐(1,3,5,7‐tetra­aza­tri­cyclo[3.3.1.1^3,7]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 Cd^II 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 Cd^II 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.     

Specific heat on Sr<Subscript>2</Subscript>Nb<Subscript>2</Subscript>O<Subscript>7</Subscript> and Sr<Subscript>2</Subscript>Ta<Subscript>2</Subscript>O<Subscript>7</Subscript>

Summary Specific heats on the single crystals of Sr₂Nb₂O₇, Sr₂Ta₂O₇ and (Sr_1-xBa_x)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 T_INC (=495 K) on Sr₂Nb₂O₇ and at the super-lattice phase transition of T_SL (=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 T_LOW (=95 K) on Sr₂Nb₂O₇. The transition temperature T_LOW decreases with increasing Ba content x and it vanishes for samples of x>2%.     

Glass formation in the CaO-Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>-B<Subscript>2</Subscript>O<Subscript>3</Subscript> and SrO-Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>-B<Subscript>2</Subscript>O<Subscript>3</Subscript> systems

A physicochemical study of glasses based on the MO-Bi₂O₃-B₂O₃ and SrO-Bi₂O₃-B₂O₃ systems was performed. Glass formation regions were found. The structural and optical properties, as well as the thermal behavior of the glasses, were studied.     

3,3,10,10‐Tetra­methyl‐1,2‐di­thia‐5,8‐di­aza­cyclo­deca‐4,8‐diene

The title compound, C₁₀H₁₈N₂S₂, acts as an important precursor for the synthesis of the pharmaceutically important di­amine­di­thiol ligand system. The mol­ecule has a local twofold axis and the arrangement of the S₂N₂ donor atoms in the macrocycle is anticlinal.     

4‐Hydro­xy‐3‐methoxy­benz­aldehyde 4,5‐di­azafluoren‐9‐yl­idene­hydrazone

The whole mol­ecule of the title compound, C₁₉H₁₄N₄O₂, is essentially planar, with a highly conjugated π system. In the crystal, the mol­ecules are packed as chains along the [011] direction connected by O—H?N intermolecular hydrogen bonds.     

Methyl­tri­phenyl­stibonium tetra­fluoro­borate

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)°.     

Preparation and characterization of Pb<Subscript>0.56</Subscript>Sr<Subscript>0.44</Subscript>Zr<Subscript>0.52</Subscript>Ti<Subscript>0.48</Subscript>O<Subscript>3</Subscript> inverse opal

Pb_0.56Sr_0.44Zr_0.52Ti_0.48O₃ (PSZT) inverse opal photonic crystals (PCs) have been synthesized by a process of self-assembly in combination with a sol–gel procedure. PSZT inverse opals show pure perovskite structure with good orders in three dimensions. The evident photonic band gaps have been observed in the transmittance spectra with a blue-shift phenomenon due to the decrease of opal template periods. PSZT inverse opals also exhibit the reflection peaks in basic agreement with the calculated results. This three-dimensional (3D) ordered PSZT inverse opals have shown interesting optical characteristics and potential applications in optoelectronic and photonic devices.