中英化学教材中“化合价一氧化态”表述方法及思考

《化学故事情节AS》是英国索尔特高级化学课程的教材之一,将该教材中有关“氧化态”这一概念的表述与我国中学化学教材中“化合价”的表述进行比较,从知识概念学习的一致性角度论述了我国中学化学教材中使用“氧化态”代替“化合价”的合理性及其优点,建议我国中学化学教材编写时进行调整.     

中学阶段同价硫元素氧化还原性的教学探讨——兼谈对“化学”之我见

1 由"深究"发问谈起 中学化学教学中,一般从元素的化合价讨论物质的氧化性和还原性,如"最低价只有还原性、最高价只有氧化性,中间价既有氧化性、又有还原性"已成为广大化学教师较为一致的认识.然而,对于同一元素在同样的化合价时是否具有相同强弱的氧化性和还原性?往往需结合具体的化学反应来说明这一事实,不再解释为什么存在着一种差异,即使有学生追问,也多以温度、浓度、酸碱度等因素的影响来敷衍,认为中学阶段很难或不能深入到物质的结构知识深度加以解释.     

形式电荷之辨析与应用

从基础的元素化学和化学结构理论入手,系统性地举例辨析形式电荷的若干相关问题,讨论其与真实电荷、化合价、氧化态和电子对之别,并举例在前沿金属配合物等领域的应用。以期对化学基础教学与推广有助。     

从“得失氧”到“极性翻转”:氧化还原反应概念的历史演变

18世纪末,拉瓦锡在氧化学说范式下,建立了“得失氧”角度上的氧化还原反应的概念。19世纪,约翰逊在化合价学说的基础上,发现氧化还原反应的共同特征是“化合价升降”,其概念扩大至反应前后化合价发生升降的一类反应。20世纪初,弗莱从“电子转移”的角度解释了化合价升降的原因,揭示了氧化还原反应的微观本质。1948年,格拉斯顿在价键理论和电负性基础上,从“氧化数变化”的角度提出了氧化还原反应的人为表征概念。20世纪末,古德斯坦和李良助分别从“电负性顺序”和“极性翻转”角度提出了氧化还原反应的现代理解。氧化还原反应概念的发展史,反映了化学思想的发展和科学认识的变化,对化学研究有重要的启示。     

组织学生探究有机氧化还原反应

氧化还原反应是中学化学中的重点,也是教与学的难点。在初中化学中,从得氧失氧的角度来认识氧化还原,在高中化学中从化合价升降和电子转移(得失或偏移)角度进一步揭示氧化还原反应的实质和规律,从而使学生形成了完整的氧化还原反应的概念,即：     

我国海峡两岸中学化学基本概念与化学用语的区别简介

通过对我国海峡两岸高中新课程化学教科书的比较,对两岸教科书中化学基本概念表述与化学用语的表达进行了对比分析研究,为两岸高中化学教学交流与课程教材建设提供参考。     

大一化学如何处理平衡常数

自从化学热力学的基础知识引进大一化学后,可以从能量角度讨论化学反应进行的方向和限度,比中学化学只讨论复分解反应和某些氧化还原反应(或置换反应)的定性规律,提高了理论的深度和层次,也有利于贯穿整个课程的教学,并使我国普通化学教材的理论深广度和美英苏(前)相近。但是,教学中也出现了一些新问题。当前,如何处理平衡常数是个较重要的     

化合价的历史演变

回顾了化合价概念的发展历史,其中包括化合价概念的提出、化学结构理论的创立、化合价的电子理论的发展、基于现代化学键理论的化合价规则等.介绍了区别化合价与氧化数的相关论述,以助于对化合价概念的理解.     

氨催化氧化演示实验的探究

分析了中学化学教材中氨催化氧化演示实验成败的关键因素,根据化学原理对反应用的药品、用量及实验装置进行了适合课堂教学实验效果的探究,避免了以往实验装置和操作的复杂及实验现象出现的不确定性,可以在短时间内轻松操作就获得明显、准确的实验现象。     

引领实验课程改革促进实验素养发展——评郑长龙教授主编的《化学实验课程与教学论》

回顾我国近几十年来,高师化学教育专业为了培养未来化学教师的从教能力,并体现化学学科以实验为基础的特点,和开设“中学化学教材教法”课程的同时,还设置了研究中学化学实验的课程。早在20世纪50年代,有些院校就选择部分中学化学教学中容易发生问题的实验,在教师指导下让学生演练,探索成败关键,掌握操作技能。     

Furyl- and thienyl-silatranes and germatranes

We review our research on the synthesis and study of the physical and biological properties of furyl- and thienylgermatranes and -silatranes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 725–732, June, 1992.     

Review and patents and literature

The use of the insect cell/baculovirus expression system for producing recombinant proteins of bacterial, plant, insect, and mammalian origin has become widespread. The popularity of this eukaryotic expression system is due to many factors, including (1) potentially high protein expression levels, (2) ease and speed of genetic engineering, (3) ability to accommodate large DNA inserts, (4) protein processing similar to higher eukaryotic cells (e.g., mammalian cells), and (5) ease of insect cell growth (e.g., suspension growth). The following review of the literature discusses two engineering aspects of recombinant protein synthesis by insect cell cultures: bioreactor scale-up and insect cell line selection. Following this review patent abstracts and additional literature pertaining to expression of recombinant proteins in insect cell culture are listed.     

Ground- and excited-state aromaticity and antiaromaticity in benzene and cyclobutadiene

The aromaticity and antiaromaticity of the ground state (S 0), lowest triplet state (T 1), and first singlet excited state (S 1) of benzene, and the ground states (S 0), lowest triplet states (T 1), and the first and second singlet excited states (S 1 and S 2) of square and rectangular cyclobutadiene are assessed using various magnetic criteria including nucleus-independent chemical shifts (NICS), proton shieldings, and magnetic susceptibilities calculated using complete-active-space self-consistent field (CASSCF) wave functions constructed from gauge-including atomic orbitals (GIAOs). These magnetic criteria strongly suggest that, in contrast to the well-known aromaticity of the S 0 state of benzene, the T 1 and S 1 states of this molecule are antiaromatic. In square cyclobutadiene, which is shown to be considerably more antiaromatic than rectangular cyclobutadiene, the magnetic properties of the T 1 and S 1 states allow these to be classified as aromatic. According to the computed magnetic criteria, the T 1 state of rectangular cyclobutadiene is still aromatic, but the S 1 state is antiaromatic, just as the S 2 state of square cyclobutadiene; the S 2 state of rectangular cyclobutadiene is nonaromatic. The results demonstrate that the well-known "triplet aromaticity" of cyclic conjugated hydrocarbons represents a particular case of a broader concept of excited-state aromaticity and antiaromaticity. It is shown that while electronic excitation may lead to increased nuclear shieldings in certain low-lying electronic states, in general its main effect can be expected to be nuclear deshielding, which can be substantial for heavier nuclei.     

Determination and study on residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil

A QuEChERS (quick, easy, cheap, effective, rugged, and safe) method for the determination of benazolin-ethyl and quizalofop-p-ethyl in rape and soil by high-performance liquid chromatography-tandem mass spectrometry has been developed in this study. The residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil were determined with the developed method. The half-lives of benazolin-ethyl in rape straw and soil were 3.7–5.1 days and 14.3–26.3 days, respectively. The half-lives of quizalofop-p-ethyl in rape straw and soil were 5.0-6.1 days and 0.3–9.7 days, respectively. The residue of benazolin-ethyl and quizalofop-p-ethyl in rapeseed and soil were below the detection limit (i.e., 0.5?mg?kg^?1, the maximum residue level of European Union for quizalofop-p-ethyl).     

Syntheses and structures of P-anilino-P-chalcogeno- and P-anilino-P-iminodiazasilaphosphetidines and their group 12 and 13 metal compounds

The P-anilino-P-chalcogeno(imino)diazasilaphosphetidines [Me(2)Si(mu-N(t)Bu)(2)P=E(NHPh)] (E = O (3), S (4), Se (5), N-p-tolyl (6)) were synthesized by oxidizing the P-anilinodiazasilaphosphetidine [Me(2)Si(N(t)Bu)(2)P(NHPh)] (2) with cumene hydroperoxide, sulfur, selenium, and p-tolyl azide, respectively. The lithium salt of 4 reacted with thallium monochloride to produce ([Me(2)Si(mu-N(t)Bu)(2)P=S(NPh)-kappaN-kappaS]Tl)(7), which features a two-coordinate thallium atom. Treatment of 4-6 with AlMe(3) gave the monoligand dimethylaluminum complexes ([Me(2)Si(mu-N(t)Bu)(2)P=E(NPh)-kappaN-kappaE]AlMe(2)) (E = S (8), Se (9), N-p-tolyl (10)), respectively. In these complexes the aluminum atom is tetrahedrally coordinated by one chelating ligand and two methyl groups, as a single-crystal X-ray analysis of 8 showed. A 2 equiv amount of 4-6 reacted with diethylzinc to produce the homoleptic diligand complexes ([Me(2)Si(mu-N(t)Bu)(2)P=E(NPh)-kappaN-kappaE](2)Zn)(E = S (11), Se (12), N-p-tolyl (13)). A crystal-structure analysis of 11 revealed a linear tetraspirocycle with a tetrahedrally coordinated, central zinc atom.     

多环芳二酐型聚酯亚胺膜的透气性能

多环芳二酐型聚酯亚胺膜的透气性能李悦生，丁孟贤，徐纪平（浙江大学高分子科学与工程研究所，杭州，３１００２７）（中国科学院长春应用化学研究所）关键词聚醚酰亚胺，聚酯酰亚胺，膜，透气性通常的聚酰亚胺加工性能较差，在芳环二酐的苯环间引入醚键等柔性基团后，其...