“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。     

聚焦学科核心素养提升的初中化学教学探索—以“酸的化学性质”为例

以酸的化学性质为载体,对知识进行上位和深层整合,将核心知识、学习活动与评价紧密结合,借助完整的科学探究,应用“宏观、微观、符号表征相结合”的学科思维方式,增进“组成构成决定性质、性质决定用途”学科思想的理解,培养高级思维和创新能力。自主建构“元素组成和微粒种类统领角度下的基于类别认识物质化学性质”的整体思维模型,实现物质化学性质认识的角度进阶。聚焦涵盖学科知识,积淀学科核心素养,落实学科育人的初中化学教学,实现初高中衔接。     

核心素养视角下人教版新旧教材中“硫及其化合物”的对比分析*

选取人教版新旧必修化学教材中的“硫及其化合物”单元作为研究对象,基于新课标中化学学科核心素养的培养视角,明确了新课标对“硫及其化合物”的素养定位后,对新旧教材中该单元的引言、正文、栏目和插图进行对比分析。对比分析结果显示,新教材“硫及其化合物”的内容侧重“证据推理与模型认知”素养的培养,其次是“宏观辨识与微观探析”“科学态度与社会责任”素养,而在素养水平上则侧重水平1和2维度的培养,符合新课标对该主题单元的学业要求和素养定位。     

发展学生化学学科核心素养的课例研究——以“离子反应”为例

以高中化学“离子反应”概念教学为例,阐述了发展学生化学学科核心素养的课例研究思路和教学活动设计。围绕离子反应概念、离子方程式书写、离子反应发生条件等知识内容,挖掘教学内容与学科核心素养内涵的联系,创设真实且富有价值的问题情境,开设高水平的实验探究活动,注重微观分析过程,将离子反应概念的学习与从微观离子角度分析水溶液中反应的认识思路进行整合,力求发展学生的化学学科核心素养,帮助学生形成对“离子反应”概念的整体认识。     

“证据推理”在高考化学试题(全国卷)中的考查特点*

基于《普通高中化学课程标准(2017年版2020年修订)》提出的化学学科核心素养中“证据推理”的内涵及相关研究,将“证据推理”化学学科核心素养进一步解构为 “证据解读”“证据与结论的关系”“证据评估”等3个要素,并将证据按其呈现形式划分为反应机理、实验数据、工艺流程和实验方案等4种类型,在此基础上构建了“证据推理”视角下的试题分析框架,并以近5年高考化学试题(全国卷)为研究对象,总结其考查特点与规律,进而为改进化学教学提出相关建议。     

“电离与离子反应”的单元教学设计与实施*——食盐精制:从微观角度看粗盐中可溶性杂质的去除

在“食盐精制:从微观角度看粗盐中可溶性杂质的去除”的单元教学中,通过初识粗盐中的杂质、微观角度看氯化钠、微观角度看粗盐溶液、微观角度认识除杂方法、设计除杂方案并实施等活动,促进学生理解与应用电离、离子反应等核心概念,引领学生解决真实问题,形成解决除杂实验问题的基本思路,实现能力素养的发展。经过多轮次教学改进,结合教学实践及其教学效果抽提出“聚焦核心概念和学生必做实验,实现认识能力的进阶与实际问题解决过程高度融合”“通过学科实践及实验探究,建立宏观、微观、符号关联,突出证据推理,构建思维模型”“通过持续性评价活动,外显学生的前概念,促进概念转变,形成化学学科思维方式”等教学策略。     

发展学生化学学科核心素养离不开化学实验

化学实验是化学教学的重要组成部分,不仅具有教育教学功能,而且具有发展学生化学学科核心素养的功能。从认识层面、实践层面和价值追求层面来看,化学实验在发展学生科学本质观、科学实践观和科学价值观方面均发挥着不可替代的功能。教师可以利用化学实验史实呈现真实的科学发现过程,发展学生的科学本质观;可以通过引导学生对化学实验现象的观察和基于实验事实证据的推理发展学生“宏观辨识与微观探析”“证据推理和模型认知”素养;可以通过开展化学实验探究,引导学生拓宽认识视角和认识思路,发展学生“科学探究与创新意识”素养;可以通过化学实验评价发展学生的“科学态度和社会责任”素养。     

基于曲线问题情境的信息化教学尝试*——以“沉淀溶解平衡”为例

基于高中生对实验曲线理解困难的现状,为挖掘实验曲线的教学价值,以沉淀溶解平衡为例,结合课堂演示实验和教学软件,设计了“宏观微观符号曲线”多重表征教学为一体的实验探究课。根据沉淀溶解平衡实验证据,绘制实验曲线,构建微观模型和图像,从而培养学生的证据收集与应用意识,提高学生对曲线的分析和理解能力,领会各种变化曲线的来源。在曲线理解的基础上建立“溶解平衡转化”思维模型,以此为开展“曲线融入式”的问题引导型实验教学提供参考案例。     

在“过氧化钠与水反应”定量实验探究中提升核心素养*

以高中化学中“过氧化钠与水的反应”的定量化实验探究过程为例,针对反应后滴入酚酞时溶液立即变深红色,随后颜色逐渐变浅甚至褪色的反常现象,通过控制变量,多角度探析了反应历程。凸显定量化的实验活动在提升学生实验探究与创新意识、证据推理与模型认知等化学核心素养中的重要作用;归纳了元素化合物模块的实验教学活动的一般思路;更好地说明化学是一门以实验为基础的科学。     

核心素养视域下化学与生活深度融合的教学*——以“碳酸钠和碳酸氢钠的性质及应用”为例

当前“碳酸钠和碳酸氢钠”的教学中,注重2者性质的分析比较,缺少对2者在生活应用的关注和亲身实践,学生无法切身感受碳酸钠与碳酸氢钠的实用价值。在核心素养视域下,化学教学应注意与生活深度融合。通过课前设置项目式学习和实践;课中汇报实践成果、进行实验探究、解决真实情境问题,使化学与生活深度融合,帮助学生深刻理解“碳酸钠和碳酸氢钠的性质及应用”,发展学生的学科核心素养,落实教、学、评一致性的要求。     

美国AP课程中化学概念的引导式探究教学*——以“化学方程式”为例

在美国《AP化学课堂中的引导式探究活动》中,明确了概念性知识采用探究式教学方式的必要性,并根据学习圈理论依次划分出概念探究、概念形成、概念应用及概念评估4个连续的教学活动阶段,使学生能够全程参与到科学概念的形成过程中。以“化学方程式”教学内容为例,介绍了相关教学理论及在此基础上形成的探究式教学闭环,以期对国内中学有关化学概念的探究式教学改革起到一定的借鉴与参考作用。     

Total Chemical Synthesis and Biological Activities of Glycosylated and Non‐Glycosylated Forms of the Chemokines CCL1 and Ser‐CCL1

CCL1 is a naturally glycosylated chemokine protein that is secreted by activated T‐cells and acts as a chemoattractant for monocytes. 1 Originally, CCL1 was identified as a 73 amino acid protein having one N‐glycosylation site, 1 and a variant 74 residue non‐glycosylated form, Ser‐CCL1, has also been described. 2 There are no systematic studies of the effect of glycosylation on the biological activities of either CCL1 or Ser‐CCL1. Here we report the total chemical syntheses of both N‐glycosylated and non‐glycosylated forms of (Ser‐)CCL1, by convergent native chemical ligation. We used an N‐glycan isolated from hen egg yolk together with the Nbz linker for Fmoc chemistry solid phase synthesis of the glycopeptide‐^αthioester building block. 3 Chemotaxis assays of these glycoproteins and the corresponding non‐glycosylated proteins were carried out. The results were correlated with the chemical structures of the (glyco)protein molecules. To the best of our knowledge, these are the first investigations of the effect of glycosylation on the chemotactic activity of the chemokine (Ser‐)CCL1 using homogeneous N‐glycosylated protein molecules of defined covalent structure.     

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.     

Interaction of solid electrolyte La<Subscript>0.88</Subscript>Sr<Subscript>0.12</Subscript>Ga<Subscript>0.82</Subscript>Mg<Subscript>0.18</Subscript>O<Subscript>2.85</Subscript> with hydrogen,water vapor,and carbon dioxide

The air,Au/La_0.88Sr_0.12Ga_0.82Mg_0.18O_2.85/Au,air cells are studied by an impedancemetry method before and after a week-long exposure at 700°C to atmospheres of hydrogen, humid air, and carbon dioxide. Blank specimens of the same electrolyte are examined by methods of x-ray diffraction, Raman scattering (RS), and x-ray photoelectron spectroscopy. The fact that the shape of the RS spectra and the shape of the electrode impedance dispersion alter unequivocally suggests that, at the very least, the electrode surface interacts with all the gases. The interaction in question is reversible in the case of hydrogen and carbon dioxide. In the case of water vapor, the interaction is irreversible.Translated from Elektrokhimiya, Vol. 41, No. 2, 2005, pp. 198–205.Original Russian Text Copyright © 2005 by Shkerin, Kovyazina, Beresnev, Kalashnikova, Martemyanova.This revised version was published online in April 2005 with corrections to the article note and article title and cover date.     

携异戊烯基光亲和化学探针的合成和应用

应用“一锅法”耦连反应为关键步骤合成了3个同时含有异戊烯链和叠氮基团的光亲和探针分子。在光照条件下这些化合物和酿酒酵母总蛋白反应后,经过点击反应与含有生物素的报告分子连接,再进行亲和素印迹分析,初步表明它们可作为钓取与异戊烯链相互作用蛋白的化学探针。     

Synthesis of Disulfide Surrogate Peptides Incorporating Large‐Span Surrogate Bridges Through a Native‐Chemical‐Ligation‐Assisted Diaminodiacid Strategy

The use of synthetic bridges as surrogates for disulfide bonds has emerged as a practical strategy to obviate the poor stability of some disulfide‐containing peptides. However, peptides incorporating large‐span synthetic bridges are still beyond the reach of existing methods. Herein, we report a native chemical ligation (NCL)‐assisted diaminodiacid (DADA) strategy that enables the robust generation of disulfide surrogate peptides incorporating surrogate bridges up to 50 amino acids in length. This strategy provides access to some highly desirable but otherwise impossible‐to‐obtain disulfide surrogates of bioactive peptide. The bioactivities and structures of the synthetic disulfide surrogates were verified by voltage clamp assays, NMR, and X‐ray crystallography; and stability studies established that the disulfide replacements effectively overcame the problems of disulfide reduction and scrambling that often plague these pharmacologically important peptides.     

Interatomic interactions and electronic structure of NbSe<Subscript>2</Subscript> and Nb<Subscript>1.25</Subscript>Se<Subscript>2</Subscript> nanotubes

Atomic models of achiral NbSe₂ nanotubes are suggested. Band structure calculations have been performed to investigate the electronic structure and determine the parameters of interatomic interactions. The distribution of the density of states and pair bond occupancies of NbSe₂ nanotubes are analyzed in relation to the type of the atomic configuration and the tube diameter; the results are compared with the band structure of the 2H-NbSe₂ crystal. Calculations have been carried out on hypothetical superstoichiometric nanotubes with a formal composition Nb_1.25Se₂ as possible quasi-one-dimensional nanoforms of autointercalated niobium diselenide.Original Russian Text Copyright © 2004 by A. N. Enyashin, V. V. Ivanovskaya, I. R. Shein, Yu. N. Makurin, N. I. Medvedeva, A. A. Sofronov, and A. L. IvanovskiiTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 579–588, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

<Superscript>63</Superscript>Cu and <Superscript>139</Superscript>La NMR and chemical bonding in anion-deficient perovskite LACu<Subscript>0.81</Subscript>Ni<Subscript>0.19</Subscript>O<Subscript>2.5+δ</Subscript>

The ⁶³Cu and ¹³⁹La NMR spectra of the low-(δ = 0.25) and high-temperature (δ = 0) phases of lanthanum cuprate LACu_0.81Ni_0.19O_2.5+δ have been obtained. Quantum chemical calculations of the electronic structure of the high-temperature phase have been performed. It is found that the observed metal-semiconductor phase transition is attended by changes in the degree of atomic ordering and in the character of electronic conductivity over certain types of “copper” centers.     

MoS<Subscript>2</Subscript> single slab as a model for active component of hydrodesulfuration catalyst: a quantum chemical study 1. Molecular and electronic structure of Mo<Subscript>12</Subscript>S<Subscript>24</Subscript> macromolecule and its adsorption complex with H<Subscript>2</Subscript>S

The molecular and electronic structure of Mo₁₂S₂₄ macromolecule as the MoS₂ single slab structure was calculated by the density functional theory (DFT) method with the B3P86 hybrid exchange-correlation functional. The results of calculations point to slight relaxation of coordinatively unsaturated Mo and S atoms, which is consistent with the published data. The calculated width of the forbidden band (0.85–0.98 eV) is comparable with the experimental value (1.30 eV) and similar to that obtained from DFT calculations with periodic boundary conditions (0.89 eV). The surface Mo centers in the Mo₁₂S₂₄ macromolecule are more reduced than the internal (Mo^IV) atoms. In order to characterize the adsorption capacity of coordinatively unsaturated Mo centers, a Mo₁₂S₂₄·6H₂S adsorption complex was calculated. The structure and energy characteristics of the adsorption complex point to a weak donor-acceptor interaction of the π-lone pair of H₂S molecule with the surface (reduced) Mo centers. The active center of thiophene hydrodesulfuration catalysts is formed as a result of the oxidative addition of hydrogen followed by occlusion of hydrogen into the MoS₂ matrix. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2189–2193, October, 2005.     

Chemical bonding and electronic structure of LaMnO<Subscript>3</Subscript> and La<Subscript>0.75</Subscript>MnO<Subscript>3</Subscript> orthorhombic crystals

The electronic structure of the LaMnO₃ orthorhombic crystal of a stoichiometric composition and of La_0.75MnO₃ crystals with a La vacancy in the unit cell is calculated in the LSDA+U approximation of density functional theory. The calculations showed that LaMnO₃ is an insulator with a forbidden gap of 0.5 eV and with antiferromagnetic ordering of magnetic moments. The magnetic moment on the manganese ions is 3.78 BM. The La atom has ionic bonds in the lattice, while the bond between oxygen and manganese is covalent. After lanthanum has been removed, geometry optimization of the unit cell leads to La_0.75MnO₃ stable structures. In one of the structures, which is lower in energy, the states of manganese may be attributed to Mn⁴⁺ ions. In both structures with removed lanthanum, the oxygen ions have reduced effective charge, so that one can speak about O^? ions appearing along with O^2? in the structure. The oxygen, as well as lanthanum and manganese, ions are nonequivalent in these structures; their nonequivalence is primarily reflected by the local densities of states. This leads to charge and magnetic nonequivalence of ions. In La_0.75MnO₃ crystals, the degree of bond covalence between manganese and oxygen decreases.