Earticle

The solvolysis rate constants of 5-nitro-2-furoyl chloride (5-$NO_2(C_4H_2O)$-2-COCl, 1) in 27 different solvents are well correlated with the extended Grunwald-Winstein equation, using the $N_T$ solvent nucleophilicity scale and YCl solvent ionizing scale, with sensitivity values of $1.20{\pm}0.05$ and $0.37{\pm}0.02$ for l and m, respectively. The activation enthalpies (${\Delta}H^{\neq}$) were 5.63 to $13.0kcal{\cdot}mol^{-1}$ and the activation entropies (${\Delta}S^{\neq}$) were -25.9 to $-43.4cal{\cdot}mol^{-1}{\cdot}K^{-1}$, which is consistent with the proposed bimolecular reaction mechanism. The solvent kinetic isotope effect (SKIE, $k_{MeOH}/k_{MeOD}$) of 2.65 was also in accord with the $S_N2$ mechanism and was possibly assisted using a general-base catalysis. The product selectivity (S) for solvolysis of 1 in alcohol/water mixtures was 1.2 to 11, which is also consistent with the proposed bimolecular reaction mechanism.

The solvolysis rate constants of 2,2,2-trichloroethyl chloroformate ($Cl_3CCH_2OCOCl$, $\mathbf{3}$) in 30 different solvents are well correlated with the extended Grunwald-Winstein equation, using the $N_T$ solvent nucleophilicity scale and the $Y_{Cl}$ solvent ionizing scale, with sensitivity values of $1.28{\pm}0.06$ and $0.46{\pm}0.03$ for $l$ and $m$, respectively. The activation enthalpies (${\Delta}H^{\neq}$) are 10.1 to 12.8 $kcal{\cdot}mol^{-1}$ and the activation entropies (${\Delta}S^{\neq}$) are -27.8 to -36.8 $cal{\cdot}mol^{-1}{\cdot}K^{-1}$, which is consistent with the proposed bimolecular reaction mechanism. The kinetic solvent isotope effect ($k_{MeOH}/k_{MeOD}$) of 2.39 is also in accord with $S_N2$ mechanism probably assisted by general-base catalysis.

This report shows the rates of solvolyses for phenyl methanesulfonyl chloride ($C_6H_5CH_2SO_2Cl$, I) in ethanol, methanol, and aqueous binary mixtures incorporating ethanol, methanol, acetone, 2,2,2-trifluroethanol (TFE) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) are reported. Three representative solvents, studies were made at several temperatures and activation parameters were determined. The thirty kinds of solvents gave a reasonably precise extended Grunwald-Winstein plot, coefficient (R) of 0.954. The sensitivity values (l = 0.61 and m = 0.34, l/m = 1.8) of phenyl methanesulfonyl chloride (I) were smaller than those obtained for benzenesulfonyl chloride ($C_6H_5SO_2Cl$, II; l = 1.01 and m = 0.61) and 2-propanesulfonyl chloride ($(CH_3)_2CHSO_2Cl$, III; l = 1.28 and m = 0.64). As with the two previously studied solvolyses, an $S_N2$ pathway with somewhat ionization reaction is proposed for the solvolyses of I. The activation parameters, ${\Delta}H^{\neq}$ and ${\Delta}S^{\neq}$, were determined and they are also in line with values expected for a bimolecular reaction mechanism. The kinetic solvent isotope effect of 2.34 in $CH_3OH/CH_3OD$ is in accord with a bimolecular mechanism, probably assisted by general-base catalysis.

The rate constants of solvolyses of 2,2,2-trichloro-1,1-dimethylethyl chloroformate ($\underline{I}$) in 33 solvents can be well correlated using the extended Grunwald-Winstein equation, with incorporation of the $N_T$ solvent nucleophilicity scale and the $Y_{Cl}$ solvent ionizing scale, with sensitivities towards changes in the scale having values of $1.42\;{\pm}\;0.09$ for l and $0.39\;{\pm}\;0.05$ for m, respectively. The activation enthalpies are ${\Delta}H^{\neq}\;=\;12.3$ to $14.5\;kcal{\cdot}mol^{-1}$ and the activation entropies are -28.2 to $-35.5\;cal{\cdot}mol^{-1}{\cdot}K^{-1}$, consistent with the proposed bimolecular reaction mechanism. The kinetic solvent isotope effect of 2.14 in MeOH/MeOD is in accord with a bimolecular mechanism, probably assisted by general-base catalysis.

In this study, we investigated the effects of cooperative learning by the levels of students' performance goal orientation in science classes on 6th graders' science achievement and science learning motivation. Two classes (47 students) from an elementary school were respectively assigned to a control group and a treatment group. A performance goal orientation test and a science learning motivation test were administered as pretests. The intervention of cooperative learning lasted for 24 class periods. A researcher-made achievement test and the science learning motivation test were administered after the instructions. ANCOVA results indicated that the score of the treatment group was significantly higher than that of the control group in the achievement test. However, no interaction was found between the cooperative learning treatment and the levels of students' performance goal orientation. There were significant aptitude-treatment interactions in science learning motivation.

In this study, the effects of concept mapping with feedbacks providing explanatory comments on students' achievement, science learning anxiety, and science learning motivation were investigated in the undergraduate general chemistry course. The aptitude-treatment interactions between students' level of mastery goal orientation and the concept mapping with explanation feedback treatment were also examined. Sixty-seven freshmen from an university of education were assigned to a control group and a treatment group. The tests of mastery goal orientation, science anxiety, and science learning motivation were administered as pretests. For the treatment group, feedback providing students with explanatory comments through whole class discussion was presented after each concept mapping. Whereas the control group students were presented with opportunities solving excercise problems followed by explanation feedback. The intervention was lasted for 10 weeks (30 class periods). After the instructions, a researcher-made achievement test, the science learning anxiety test, and the science learning motivation test were administered. The results indicated that no statistically significant difference was found in students' achievement. In the science learning anxiety, however, the scores of the treatment group was significantly lower than those of the control group. The scores of the treatment group also tended to be higher, though not significant, than those of the control group in the science learning motivation. However, no significant aptitude-treatment interactions were found in all dependent variables.

The purpose of this study is to devise a new method for examining the readabilities of textbooks and to compare the readabilities of elementary school science textbooks. Third and sixth grade science textbooks were compared in terms of word, sentence, and paragraph in this study. In the word analyses, criterion suggested by Kim (2003) who classified about 238,000 words into seven categories according to their educational importances was adopted. In this study, the words from 3rd and 6th grade science textbooks were classified into four categories, and then the kinds and frequencies of words in each category were investigated. In the sentence analyses, sentences were classified either a simple sentence or a compound/complex sentence, and the ratios of each type were calculated. The average number of words in a sentence was also calculated in the sentence analyses. The ratios of conjunctions and demonstratives were examined in the paragraph analyses. The results indicated that both the kinds and frequencies of words in 3rd grade science textbook were smaller than those of 6th grade one. However, both science textbooks were similar in the distributions of words across the four categories. The ratio of simple sentences in 3rd grade science textbook was higher than that of 6th grade one, and the length of a sentence in 3rd grade science textbook was also shorter than that of 6th grade one. Both the ratios of conjunctions and demonstratives in 3rd grade science textbook were lower than those of 6th grade one.

In this study, elementary school teachers' needs for the website providing science instructional materials were examined. The participants were 151 elementary school teachers. The test for needs analysis consisted of fifty-three Likert-type items; 24 items for the content of website category and 29 items for the design of website category. Variables about participants' characteristics such as teaching career, the capability of using computers, and the frequencies of searching websites in obtaining science instructional materials were also examined. The results indicated that teachers' needs for the content of website category were significantly higher than those for the design of website category. Teachers' needs were relatively higher in the items concerning flawless materials, consistency of materials with science curriculum and/or learning objectives, information about target grade and/or related topics, free website, and the materials capable of immediate use in the content of website category. The items concerning the stability of website, the accuracy of links, providing easy and reliable searching methods, easy and fast downloading, and providing list of loaded materials showed relatively higher needs in the design of website category. In several items, teachers' needs were also changed with their individual characteristics.

Rates of solvolyses of 4-nitrophenyl phenyl thiophosphorochloridate (4-N$O_2$PhOP(S)(Cl)OPh, $\underline{1}$) in ethanol, methanol, and aqueous binary mixtures incorporating ethanol, methanol, acetone, and 2,2,2-trifluroethanol (TFE) are reported. Thermodynamic parameters were determined at several temperatures in three representative solvents. The extended Grunwald-Winstein equation was applied to 29 solvents and the correlation coefficient (R) showed 0.959. The sensitivities (l = 1.37 and m = 0.62) are similar to those obtained for diphenyl thiophosphorochloridate (($PhO)_2$PSCl, $\underline{2}$), diphenyl phosphorochloridate (($PhO)_2$POCl, $\underline{3}$), diphenyl phosphinic chloride ($Ph_2$POCl, $\underline{4}$), and diphenyl thiophosphinic chloride ($Ph_2$PSCl, $\underline{5}$). The solvolytic reaction mechanism of 4-nitrophenyl phenyl thiophosphorochloridate ($\underline{1}$) is suggested to be proceeded a $S_N$2 process as previously reported result. The activation enthalpies are shown as slightly low as ${\Delta}H^{\neq}\;=\;9.62\;to\;11.9\;kcal{\cdot}mol^{-1}$ and the activation entropies are shown as slightly high negative value as ${\Delta}S^{\neq}\;=\;-34.1\;to\;-44.9\;cal{\cdot}mol^{-1}{\cdot}K^{-1}$ compared to the expected $S_N$2 reaction mechanism. Kinetic solvent isotope effects are accord with a typical $S_N$2 mechanism as shown in the range of 2.41 in MeOH/ MeOD and 2.57 in $H_2O/D_2O$ solvent mixtures.

Rates of solvolyses of benzhydryl chloride ($Ph_2$CHCl, 1) and benzhydryl bromide ($Ph_2$CHBr, 2) in ethanol, methanol, and aqueous binary mixtures incorporating ethanol, methanol, 2,2,2-trifluoroethanol (TFE) and acetone are reported. Solvolyses were also carried out in TFE-ethanol mixtures. Application of the extended Grunwald-Winstein equation led to l value of 1.19 (1), 1.29 (2) and m value of 1.00 (1), 0.77 (2), correlation coefficient of 0.965 (1) and 0.970 (2). Sensitivities (l = 1.19 (1), 1.29 (2) and m = 1.00 (1), 0.77 (2)) were similar to those obtained for several previously studied solvolyses, in which an $S_N$2 pathway is proposed for the solvolyses of benzhydryl halides ($Ph_2$CHX, X = Cl or Br).

Rates of solvolyses of diphenyl thiophosphorochloridate ($(PhO)_2$PSCl, 1) in ethanol, methanol, and aqueous binary mixtures incorporating ethanol, methanol, acetone and 2,2,2-trifluoroethanol (TFE) are reported. For four representative solvents, studies were made at several temperatures and activation parameters were determined. The 30 solvents gave a reasonably precise extended Grunwald-Winstein plot, correlation coefficient (R) of 0.989. The sensitivity values (l = 1.29 and m = 0.64) of diphenyl thiophosphorochloridate ($(PhO)_2$PSCl, 1) were similar to those obtained for diphenyl phosphorochloridate ($(PhO)_2$POCl, 2), diphenylphosphinyl chloride ($Ph_2$POCl, 3) and diphenylthiophosphinyl chloride ($Ph_2$PSCl, 4). As with the previously studied of 3~4 solvolyses, an $S_N$ pathway is proposed for the solvolyses of diphenyl thiophosphorochloridate (1). The activation parameters, ${\Delta}H^{\neq}\;(=11.6{\sim}13.9\;kcal{\cdot}mol^{-1})\;and\;{\Delta}S^{\neq}\; (=\;-32.1\;{\sim}\;-42.7\;cal{\cdot}mol^{-1}{\cdot}K^{-1})$, were determined, and they were in line with values expected for an $S_N$2 reaction. The large kinetic solvent isotope effects (KSIE, 2.44 in MeOH/MeOD and 3.46 in $H_2O/D_2$O) are also well explained by the proposed $S_N$2 mechanism.

Rate of solvolysis of diphenylthiophosphinyl chloride in ethanol, methanol, and aqueous binary mixtures incorporating ethanol, methanol, acetone, 2,2,2-trifluoroethanol (TFE) or 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) are reported. Solvolyses were also carried out in TFE-ethanol mixtures. For five representative solvents, studies were made at several temperatures and activation parameters determined. The 29 solvents gave a reasonably precise extended Grunwald-Winstein equation plot, correlation coefficient (R) of 0.933, which improved to 0.983 when the four TFE-ethanol points were excluded. The sensitivities (l = 1.00 and m = 0.64) were similar to those obtained for dimethyl phosphorochloridate and phosphorochloridothionate and diphenylphosphinyl chloride (1). As with the four previously studied solvolyses, an $SN_2$ pathway is proposed for the solvolyses of diphenylthiophosphinyl chloride. The activation parameters, ${\Delta}H^{\neq}$ and ${\Delta}S^{\neq}$, were determined and they are also in line with values expected for an $S_N2$ reaction.

이 연구에서는 일반화학 수업에서의 개념도 작성이 초등 예비교사의 성취도, 개념 이해도, 과학에 대한 불안감, 과학교수효능감에 미치는 영향을 조사했다. 또한, 예비교사들의 학습 접근 방식과 개념도 작성 활동 사이의 적성-처치 상호작용 효과도 조사했다. 1개 교육대학교의 1학년 학생 69명을 처치 집단과 통제 집단으로 배정했다. 사전 검사로 학습 접근 방식, 과학에 대한 불안감, 과학교수효능감 검사를 실시했다. 처치는 9주 동안 진행되었는데, 처치 집단은 강의 후 개념도 작성을 했고, 통제 집단은 강의 후 교과서의 연습 문제를 풀었다. 처치가 끝난 후, 성취도, 개념 이해도, 과학에 대한 불안감, 과학교수효능감 검사를 실시했다. 연구 결과, 성취도 검사에서는 처치 집단의 점수가 통제 집단보다 유의미하게 높았다. 그러나 개념 이해도와 과학교수효능감에서는 처치 집단과 통제 집단 사이에 통계적으로 유의미한 차이가 나타나지 않았다. 과학에 대한 불안감 검사에서는 처치 집단 학생들의 불안감이 통제 집단에 비해 유의미하게 높았다. 학생들의 학습 접근 방식과 수업 처치 사이의 적성-처치 상호작용 효과는 발견되지 않았다.

In this study, the effects of concept mapping on the preservice elementary teachers' achievement, conceptual understanding, anxiety toward science, and science teaching efficacy belief were investigated in the undergraduate general chemistry course. The aptitude-treatment interaction (ATI) between preservice teachers' learning approach and concept mapping strategy was also investigated. Sixty-nine freshmen from a university of education were assigned to a control group and a treatment group. Tests regarding students' learning approach, anxiety toward science, and science teaching efficacy belief were administered as pretests. Treatment lasted for 9 weeks. In every class, students in the treatment group constructed concept maps, while those in the control group solved the problems of the textbook after the lecture. After the instructions, tests of achievement, conceptual understanding, anxiety toward science, and science teaching efficacy beliefs were administered. The results indicated that students in the treatment group significantly outperformed those of the control group in the achievement test. In the conceptual understanding and the science teaching efficacy beliefs, however, no statistically significant differences were found between two groups. Students of the treatment group showed significantly higher anxiety than their counterpart in the test of anxiety toward science. No aptitudetreatment interaction between students' learning approach and the concept mapping strategy was found.

In this study, we investigated the variables related to the science teaching efficacy beliefs of pre-service and in-service elementary school teachers. The participants were 176 freshmen and 260 seniors from an university of education and 234 teachers from 25 elementary schools located in Jeonju. Variables concerning pre-service teachers include their sex, career/study tracks (science or non-science), and the number of science courses taken either at high school or at university. Variables concerning in-service teachers include their sex, academic degree, the frequency and type of participation in science in-service training, and their teaching career experience. The Science Teaching Efficacy Beliefs Instrument was used to measure teachers' self-efficacy beliefs. The results indicated that the personal science teaching efficacy belief scores of seniors were significantly lower than those of freshmen and in-service teachers, whereas the science teaching outcome expectancy scores of seniors were significantly higher than those of freshmen. Among variables investigated, sex, career/study track, the number of science courses taken at high school, and the frequency and type of participation in science in-service training were found to significantly influence teachers' science teaching efficacy beliefs.

이 연구는 초등학교 과학 수업에 대본을 사용한 협동학습의 적용하여 그 효과를 조사하였다. 6학년 3개 학급 95명을 대상으로 '여러 가지 기체' 단원 총 9차시에 대하여 전통수업, 협동수업, 대본을 사용한 협동수업을 실시한 후, 학업 성취도, 과학 학습 동기, 과학 수업에 대한 태도를 비교하였다. 이원 공변량 분석 결과, 학업 성취도에서 수업 처치와 성취 수준 사이에 유의미한 상호작용 효과가 나타났다. 성취 수준 하위 학생들의 학업 성취도 점수는 대본을 사용한 협동학습 집단이 다른 집단보다 유의미하게 높았다. 또한 과학 학습 동기와 과학 수업에 대한 태도 점수도 대본을 사용한 협동학습 집단이 유의미하게 높았다.

In this study, the effects of scripted cooperative learning in elementary school science instruction were investigated. Three classes (95 sixth graders) were divided into three groups, including a traditional learning group, a cooperative learning group and a scripted cooperative learning group respectively. Students were taught about 'several kinds of gas' for nine class periods. After instruction, the effects upon student's achievement, science learning motivation, and attitude toward science instruction were examined. ANCOVA results indicated that there was a significant interaction effect between the treatment and achievement level in the achievement test scores. The achievement test scores of the low level students were significantly higher in the scripted cooperative learning group than those in the other groups. The science learning motivation and the attitude toward science instruction scores were also significantly higher among students in the scripted cooperative learning group.

Kinetic studies of the reaction of Z-aryl cyclopropanecarboxylates with X-pyridines in acetonitrile at 55.0 ℃ have been carried out. The reaction proceeds by a stepwise mechanism in which the rate-determining step is the breakdown of the zwitterionic tetrahedral intermediate, $T^{\pm}$. These mechanistic conclusions are drawn base on (i) the large magnitude of ρx and ρz, (ii) the positive sign of ρxz and the larger magnitude of ρxz than normal $S_N2$ processes, (iii) a small positive enthalpy of activation, Δ$H^≠$, and a large negative, Δ$S^≠$, and lastly (iv) adherence to the reactivity-selectivity principle (RSP) in all cases.