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以“物质的量的单位--摩尔”为内容,尝试由“集合”的思想引出摩尔、由摩尔引出物质的量、由12C引出摩尔质量等进行教学设计,指出关注概念的起源和发展有助于学生更加深刻和准确地理解概念所承载的意义。 相似文献
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探讨了"物质的量"教学中存在的主要问题,提出应用自主探究的交互教学软件,以探究活动为依托,以培养学生科学研究方法和逻辑推理能力为主旨,从学生已有的知识和经验出发,通过具体的可理解和可操作的问题入手,形成任务并在任务驱动下实现学生自主探究,得到结论、建立概念和导出公式。实践表明,该方法能有效帮助学生建立有关摩尔的概念和计算公式,消除对概念的迷茫,并在定量科学研究方法培养中有一定的作用。 相似文献
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通过调查发现学生在学习化学平衡之后,仍然对化学平衡中的5大中心概念问题:(1)动态平衡的判断;(2)浓度、温度、压强(体积)等对化学平衡的影响;(3)浓度、温度、压强(体积)等对化学平衡反应速率的影响;(4)盐类对溶解平衡的影响;(5)惰性气体对化学平衡的影响等存在大量的迷思概念。在此基础上论文汇总了学生在化学平衡学习过程中存在的重要迷思概念以及对重要迷思概念产生原因进行了分析,最后得出结论,传统的教学很难转变学生的迷思概念。 相似文献
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针对概念教学中向学生直接呈现概念,然后通过机械训练来实现所谓概念掌握的教学现状,以物质的量浓度概念教学为例,提出应在学生深刻理解已有概念的基础上,通过任务驱动来引导、启发,让学生自己概括出原理、规律,从而实现概念的自主、有效的建构,再通过具体问题的解决,以期达到学生真正理解概念的教学目的。 相似文献
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为探讨不同发展阶段的高中化学教师对于“物质的量”主题的认识,聚焦学科教学知识(PCK)的2个基本组成部分:(1)学生理解的知识,(2)教学策略和表征知识。基于PCK课堂观察量表和CoRe模型,对比分析新手、熟手、专家型教师关于“物质的量”主题的PCK表征。研究结果表明,不同发展阶段化学教师的PCK存在差异,教师对学生知识的理解影响了教学策略和表征方式的决策。 相似文献
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Areas of fusion and crystallization peaks of K3TaO2F4 and KTaF6 were measured using the DSC mode of a high-temperature calorimeter (SETARAM 1800 K). On the basis of these quantities, considering
the temperature dependence of the calorimeter sensitivity, values of the fusion enthalpy of K3TaO2F4 at the fusion temperature of 1181 K of (43 ± 4) kJ mol−1 and of KTaF6 at the fusion temperature of 760 K of (8 ± 1) kJ mol−1 were determined. 相似文献
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Russell G. Baughman Kenneth L. Martin Rajendra K. Singh James O. Stoffer 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(2):o103-o106
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. 相似文献
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科学史奠基者乔治·萨顿在《科学史导论》第二卷的第一部分对我国宋代酿酒著作《北山酒经》予以了简要描述,出现了“spirits”“distillation”等字样;而《北山酒经》被众多学者认为其描述对象是发酵酒(黄酒)。本文从东西方蒸馏技术和相关著作的文本分析对《科学史导论》中提及的蒸馏技术和蒸馏酒存在的可能性提出了质疑。 相似文献
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I. B. Bakhtiyarly D. Sh. Abdinov R. A. Ismaiyilova E. A. Geidarova 《Russian Journal of Inorganic Chemistry》2008,53(4):624-627
Phase equilibria in the Sb2Te3-Gd2Te3-Bi2Te3 ternary system have been studied using differential thermal analysis, namely, X-ray powder diffraction, microstructure examination, thermodynamic analysis, and microhardness and alloy density measurements. Phase diagrams of some polythermal joins and liquidus surface have been constructed. The regions of primary crystallization of phases and the coordinates of all invariant and univariant equilibria in the system under investigation have been established. 相似文献
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V. M. Novotortsev S. F. Marenkin I. V. Fedorchenko A. V. Kochura 《Russian Journal of Inorganic Chemistry》2010,55(11):1762-1773
The results of studying phase equilibria of ternary AIIBIVCV systems have been reported. Physicochemical foundations have been developed for the synthesis of new ferromagnets with Curie
temperatures above room temperature structurally compatible with basic semiconducting materials. Methods of synthesis and
physicochemical properties of manganese-doped AIIBIVC2V ferromagnets have been described. The results of theoretical simulation of magnetic properties have been considered and basic
approaches to the explanation of the emergence of ferromagnetism in AIIBIVC2V doped with 3d metals have been surveyed. The most promising ways to produce and study dilute magnetic semiconductors as spintronics materials
have been presented. 相似文献
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N. V. Pervukhina S. V. Borisov S. A. Magarill D. Yu. Naumov V. I. Vasiliev B. G. Nenashev 《Journal of Structural Chemistry》2004,45(4):720-723
The results of structural studies of the synthetic analog of the radtkeite mineral Hg3S2Cl1.00I1.00 are analyzed. The crystal structure of the compound has been refined; the unit cell parameters are a
m = 16.827(4) , b
m = 9.117(1) , c
m = 13.165(5) , = 130.17(2)°, V = 1543.3(8) 3, space group C2/m, Z = 8, R = 0.0527. A possible transition a
0
= a
m; b
0
= a
m + 2c
m; c
0
= –b
m to the pseudo-orthorhombic F cell previously determined for radtkeite, where one of the angles (
0
) is slightly different from 90° (89.55°), has been found. Each sulfur atom in the structure is bonded to three mercury atoms, forming SHg3 umbrellas with distances 2.240(6) –2.474(8) and angles HgSHg 94.7(2)°–102.9(2)°. The SHg3 fragments are linked through Hg vertices to form corrugated [Hg12S8] layers. The halogen atoms lie inside and between the [Hg12S8] layers; the distances are Hg-Cl and Hg-I 2.783(7) , 2.961(7) , and 3.083(4) –3.311(3) , respectively.Original Russian Text Copyright © 2004 by N. V. Pervukhina, S. V. Borisov, S. A. Magarill, D. Yu. Naumov, V. I. Vasiliev, and B. G. NenashevTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 755–758, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date. 相似文献
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Quantum-chemical calculations of the geometry and energies of nine possible isomers of 12-vertex cobaltacarborane CpCoC2B9H11 (1) were carried out by the DFT method (PBEPBE/DGDZVP/DGA1). Thermodynamic stability of the isomers increases with increasing
distance between the carbon atoms in the cage and is virtually independent of the position of the CpCo vertex. The relative
stabilities of the 1,2,3-(17.57 kcal mol−1), 1,2,4-(3.72 kcal mol−1), and 1,2,9-isomers of 1 (0 kcal mol−1) are similar to the corresponding values for the ortho (17.61 kcal mol−1), meta (3.21 kcal mol−1), and para isomers (0 kcal mol−1) of carborane C2B10H12. The results of the present study confirm a close similarity of the CpCo and BH fragments in metallacarborane chemistry.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1557–1559, July, 2005. 相似文献
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Areas of fusion and crystallization peaks of K3NbO2F4 were measured using the DCS mode of a high-temperature calorimeter (SETARAM 1800 K). On the basis of these quantities, considering
the temperature dependence of the calorimeter sensitivity, the value of the fusion enthalpy of K3NbO2F4 of (98 ± 6) kJ mol−1 was determined at the fusion temperature of 1257 K. 相似文献
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The corroding process of six glasses of the Na2O-K2O-CaO-ZrO2-SiO2 system with ZrO2content 0–2.13 mass % by water was observed during static tests at 121°C and pressure of 0.25 MPa in steam sterilizer. Significant
increase of Na+ and K+ content in leachates was observed after the addition of ZrO2 into glass. Further increase of the content of ZrO2 in glasses slowed down the rate of Na+ and K+ leaching. The leaching process of SiO2 as well as Na+, K+, and Ca2+ ions was evaluated on the basis of comparison with model leaching processes. Variation of the concentrations of Na+, K+, Ca2+, and SiO2 in leachates with time was described by empirical equation. Observed changes in the initial leaching rates of Na+, K+, Ca2+, and SiO2 can be ascribed to the content of ZrO2 in glasses. The presence of ZrO2 in glasses reduced the overall rate of glass dissolution. 相似文献
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I. E. Zanin K. B. Aleinikova M. M. Afanasiev M. Yu. Antipin 《Journal of Structural Chemistry》2004,45(5):844-848
The structure of Zn3P2 (P 42/nmc, a = b = 8. 0785 Å, c = 11. 3966 Å) was solved and refined to R = 3. 2% in a precision X-ray diffraction experiment (λ-MoK
a, graphite monochromator on a primary beam, 27,496 reflections) . Interatomic distances and bond angles have been determined. The fcc lattice of the structure is built from phosphorus atoms, and the zinc atoms occupy 3/4 of all tetrahedral voids; the structure is described by two equivalent models where 1/4 occupied (by zinc atoms) and 1/4 vacant voids change places. The zinc atoms that occupy the voids following the diamond principle do not change places.Original Russian Text Copyright © 2004 by I. E. Zanin, K. B. Aleinikova, M. M. Afanasiev, and M. Yu. Antipin__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 889–892, September–October, 2004. 相似文献