基于“历史复演法”的化学教学设计研究——以“质量守恒定律”为例

化学发展的历史能够作为重要的教学设计资源。将历史上的化学家开展科学研究和解决科学问题的过程，设计为可供课堂教学应用的学生问题，需要经过历史事件考察、学生水平分析、问题转化等步骤。以质量守恒定律为例，探讨了基于“历史复演法”的化学教学设计框架与实施。     

基于OBE理念的“化学教学设计与实施”课程建设与教学实践*

介绍了化学教师教育核心课程“化学教学设计与实施”课程建设和教学实践过程。该过程基于OBE理念,以培养中学化学骨干教师的成果为导向,确立课程目标,并围绕“素养为本”的化学教学设计过程模型建构课程、组织课程内容、设计课程教法、运用多元课程评价方式一体化进行课程整体变革设计,精准指向师范生未来职业发展必备素养。研究表明,成功实现了教学改革和教学相长,实现了全国同行认可的辐射效果。同时针对课程不足,提出了进一步改进方向和措施,并对未来做出了展望。     

基于OBE理念的混合式教学模式在“食品化学”课程教学中的实践

基于OBE教学理念,在食品化学课程教学中探索了混合式教学模式,从课程目标确立、教学内容优化、课程资源建设、课程考核、课程目标达成度等方面进行系统的教学设计。以知识点美拉德反应的教学为例介绍了混合式教学实施过程,并对改革效果进行了分析。实践表明：基于OBE理念的混合式教学模式有利地促进了学生对知识的掌握,提升学生综合能力,取得了显著的教学效果。     

化学专家教师和新手教师的教学决策特征——基于“沉淀溶解平衡”的教学设计

教学决策包括课前、课中和课后3个时间段的决策,教学决策一直伴随着教学进程。从教学实践看,课前教学设计中的决策是教师普遍感到最困难的事情。教学决策从概念上与教学设计有重叠与交叉的部分,同时2者也有区别,其中教学决策的重点是在于选择。教师教学决策主要有运用程序化决策和非程序化决策、以个人决策为主和需要基于一定的情境性等特征。通过4位教师以"沉淀溶解平衡"为内容而设计的4个问题进行分析,初步得出专家教师和新手教师在化学教学决策中的差异,提出提升教师教学决策能力的途径。     

基于概念转变模型和认知冲突图的课例研究* ——以“化学平衡的动态性”为例

基于概念转变模型,介绍了典型认知冲突图模型的构成要素(新认知、差异性事件、迷思概念、目标科学概念、批判性事件或解释、关联科学概念、支持性认知)及其建构过程。以“化学平衡的动态性”的认知冲突图的建立为例,呈现了相关的教学设计并提出了冲突图教学的实施建议。     

用身边化学事件为教学素材的高三专题复习设计——以金属氢氧化物专题复习为例

用身边化学事件为教学素材的高三专题复习,能让学生巩固知识、提升能力,并对身边化学事件有更正面的化学认识,具有“学生喜欢又符合高考要求”的特点。用基于无机阻燃剂研制的金属氢氧化物专题复习设计为例,说明素材的获取、目标的确定及教学内容与过程的设计等具体过程,并分析此课堂的成效。     

基于化工模拟的氨法烟气脱硫工艺设计案例教学探讨

在化工设计课程教学中将科研项目成果“氨法烟气脱硫工艺设计项目”转化为典型教学案例,并结合现代化工设计方法,引入化工模拟软件Aspen Plus进行化工过程设计,让学生更直观地理解气液两相吸收过程所涉及的化学反应设计、分离序列的选择与应用、能量匹配与集成优化等,使课程理论教学更加生动,将复杂的化工设计过程讲解透彻,提高教学质量,提高学生实际工程设计能力。     

“原子结构与元素性质”主题模型建构教学的探索

从2003年起至今,北京师范大学化学教育研究团队围绕“原子结构与元素性质”主题开展了跨越初中、高中必修、高中选择性必修的模型建构教学探索,涉及原子的构成微粒及空间分布、核外电子的运动状态、核外电子的排布规律以及元素性质等不同子主题。在这些教学探索中,梳理和还原了科学家解决问题的过程,对科学家所做实验进行再现、模拟,依据科学家在基于实验证据建构原子结构模型时的推理论证过程设计并指导学生开展模型建构活动,使学生理解、评价或参与模型建构的过程,促进学生建模能力和科学本质观的形成与发展。     

促进“深度学习”的教学实践与思考——以“基于桃酥烘焙配方的实验探究”为例

以“基于桃酥烘培配方的实验探究”单元课的设计与实施为例,从情境素材的选取、课堂问题的设计、课堂任务的确定、学习活动的设计、持续性评价方案的设计等方面论述了促进“深度学习”教学的生成过程。     

基于翻转课堂-PBL的混合式“金课”教学*——以“药物分析”为例

以创新应用能力及岗位需求重构课程标准,更新教学方法和教学手段,从教学设计、教学实施、教学评价、教学效果等4个方面系统地探索了基于翻转课堂-PBL教学的药物分析课程教学模式建设与应用,旨在形成多元化、多层次的药物分析教学新体系,将“以教师教为主”的教学模式转变为“以学生学为主”,让学生化“被动”为“主动”学习,锻炼学生自主学习能力,增强学生团队协作及分析解决问题的能力,启发学生创新应用能力。     

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.     

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.     

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.     

{[(N‐Methyl‐p‐toluidino)­di­phenyl­phospho­ranyl­idene]­methyl}(N‐methyl‐p‐toluidino)­di­phenyl­phospho­nium iodide

The cationic part of the homodifunctional amino­phospho­ranyl ligand, C₄₁H₄₁N₂P₂⁺·I^?, shows interesting features associated with the N—P—C—P—N skeleton. The P—C(H) bond distances [1.696 (3) and 1.697 (3) Å] possess partial double‐bond characteristics. The nature of the P—C(H) and P—N bonds suggests that the positive charge is only distributed around the P—C—P atoms. The structure has near twofold symmetry through the central methyl­ide‐C atom.     

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%.     

Chemical durability of MoO<Subscript>3</Subscript>-P<Subscript>2</Subscript>O<Subscript>5</Subscript> and K<Subscript>2</Subscript>O-MoO<Subscript>3</Subscript>-P<Subscript>2</Subscript>O<Subscript>5</Subscript> glasses

Thermal and chemical durability studies of the phosphate glasses belonging to the binary MoO₃-P₂O₅ and the ternary K₂O-MoO₃-P₂O₅ systems are reported. The chemical resistant attack tests carried out on the free alkaline MoO₃-P₂O₅ glasses show that the glass associated with the P/Mo ratio 2 has the high chemical durability. It shows also a high glass transition temperature value. The above findings are interpreted in terms of the cross-link density of the glasses and the strength of the M-O bonds (M=P, Mo). The influence of K₂O addition on the properties (density, T _g, durability) of this binary high water resistant glass is studied. It is found that the chemical durability along with the other physical properties are reduced by the incroporation of K₂O in the glass matrix. The results were explained by assuming the formation of non-bridging oxygens and weak bonds. The mechanism of the dissolution of these glasses is proposed.     

Three-component systems LiBr-LiVO<Subscript>3</Subscript>-Li<Subscript>2</Subscript>MoO<Subscript>4</Subscript> and LiBr-Li<Subscript>2</Subscript>SO<Subscript>4</Subscript>-Li<Subscript>2</Subscript>MoO<Subscript>4</Subscript>

Phase equilibria in the three-component systems LiBr-LiVO₃-Li₂MoO₄ and LiBr-Li₂SO₄-Li₂MoO₄ have been studied using differential thermal analysis (DTA). Eutectic compositions have been determined (mol %): in the system LiBr-LiVO₃-Li₂MoO₄, 56.0 LiBr, 22.0 LiVO₃, and 22.0 Li₂MoO₄ with a melting temperature of 413°C; and in the system LiBr-Li₂SO₄-Li₂MoO₄, 65.0 LiBr, 14.0 Li₂SO₄, and 21.0 Li₂MoO₄ with a melting temperature of 421°C. Phase fields have been demarcated.