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。     

“四重四步”教学模式的初中化学教学实践*——以“二氧化碳和一氧化碳”为例

核心素养视域下的初中化学课堂教学需要有一个深入学科本质的教学模式。“四重四步”教学模式通过教师的“四步教学”和学生的基础性认知、本质性认知、结构性认知、价值性认知的“四重认知”实现了由基于知识点的教学到基于化学学科核心素养发展的教、学、评一体化的转变,达成学科育人的要求。     

利用游戏化教学促进“微粒观”建构*——以“原子的结构”第一课时为例

分析了初中化学微粒观的教学内容和“原子的结构”的相关教学设计,针对学生“微粒观”建构存在的难题,提出利用反馈机制,采用“寓教于乐”的游戏化教学设计,并进行实践效果访谈。不仅完成了本课时的教学目标,也让学生对化学的兴趣更加浓厚。     

落实核心概念功能价值演变的复习课教学——“溶液”单元复习

把“溶液”放到完整学科体系中,利用本原问题驱动,调取新授课储备的、与新问题情境匹配的学科理论、模型,将“核心概念、学科任务、认识角度、认识路径、能力活动、化学基本观念”融合,借助学科思维方式、方法,打通纵横联系,找寻基本规律,在思维碰撞中对自身原有认识加以修正、完善发展,形成“核心概念功能化,解决问题思路化”的系统思维模型。在学科核心素养统领下,落实核心概念功能价值演变的初中化学复习课教学。     

“素养为本”的化学课堂教学*——以“原子晶体”为例

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。     

初中化学“分子和原子”的教学逻辑——基于2011-2018年的文献分析

以2011-2018年19篇有关初中化学“分子和原子”的教学研究文献为研究对象,基于教学观念与策略分析归纳出2种主要的教学逻辑:“证据推理型”和“模型认知型”。从“初步建立微粒观”“发展微粒观”“初步形成微粒观”等3个维度对2种教学逻辑进行归纳和评析,结合教学实践提出了一个新的“模型认知型”的教学逻辑。     

初中化学“铁元素专题复习”的项目式教学——探索蒸汽眼罩的奥秘

转变初中化学复习课的教学方式,以真实情境为载体,确定“探索蒸汽眼罩的奥秘”为项目主题,引导初中学生深入开展铁元素的专题复习。详细阐述了教师对该部分内容教学的课前分析,如何确立、规划和实施项目。学生通过完成“设计实验方案证明铁的存在”“探究活性炭和氯化钠对铁生锈的影响”等2个任务,提升了学科兴趣,对铁的性质进行了系统性再造。通过手持技术监测氧浓度和温度变化探究眼罩成分的作用,学生的科学探究能力从定性过渡到定量,实现了科学探究素养的深化与进阶;通过观看科普视频了解前沿科学,拓宽了学生的生涯认知,涵养了科学精神。     

基于科学态度与社会责任的反向思维教学——以“元素化学”为例

“科学态度与社会责任”是《普通高中课程标准(2017年版)》提出的5大化学学科核心素养之一,但在课堂教学实践中对其的培养却往往流于形式和表面,使得学生并不能真正理解和认同化学学科与社会发展的密切关系。在元素化学的必修课和选修课课堂教学中进行了一系列的“反向思维”教学尝试,通过建立“当某种元素不存在”这一假设来引导学生思考此情境对社会生产生活的影响。通过此教学尝试,让学生在获得元素知识的同时,深刻认识元素价值,并理解化学科学与现代社会发展的重要关系,提升学生的社会使命感与责任感;使学生进一步树立科学利用元素资源和建设现代化祖国的远大志向。     

“二氧化碳的性质及其转化”的项目式教学——探寻二氧化碳的工业捕集方案

以探寻二氧化碳的工业捕集方案为项目主题,开展初中化学二氧化碳的性质及其转化的教学。学生通过“建立价类二维模型并设计二氧化碳的理想转化路径”“实验探究二氧化碳的实际转化”“解决二氧化碳的工业转化”等3个项目子任务理解了物质“组成、性质、变化”之间的关系,运用手持技术数字化实验探究了二氧化碳在不同碱溶液中的吸收效率,发展了实验探究能力,构建了物质转化在化工生产领域的认知模型,提高了思维迁移的能力。从“碳捕集”到“碳利用”的进阶解决问题模式,有利于学生化学学科核心素养的内化。     

信息技术与“教学评”一体化深度融合的教学实践*——以“有机合成”为例

以建构有机合成中的顺推法和逆合成分析法思维模型为载体,通过设置驱动任务,将信息技术和“教学评”一体化深度融合,促进学生结构观、发展观和转化观的形成,理解有机化学的社会价值,培养学生的宏微结合、变化观念、科学态度和社会责任等化学学科核心素养。     

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)°.     

2,4,6‐Tri­chloro­phenyl­iso­nitrile and 2,4,6‐tri­chloro­benzo­nitrile

The molecular structures of the title compounds, 2,4,6‐tri­chloro­phenyl­iso­nitrile (IUPAC name: 2,4,6‐tri­chloro­phenyl isocyanide), C₇H₂Cl₃N, and 2,4,6‐tri­chloro­benzo­nitrile, C₇H₂Cl₃N, are normal. The two structures are not isomorphous, but do contain similar two‐dimensional layers in which pairs of mol­ecules are held together by pairs of Cl?CN [3.245 (3) Å] or Cl?NC [3.153 (2) Å] interactions. The two‐dimensional isomorphism is lost through different layer‐stacking modes.