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Volume 20, Issue 2  (2011)

2011 - International Year of Chemistry:
I. Kuleff
Marie Sklodowska-Curue and the International Year of Chemistry

Full text: PDF (176 K)

83
E. Kirkova
Stereochemistry of Some Molecules and Iones of the p-Elements

Full text: PDF (749 K)

96
Letters to the Editor:
A.E. Burns
Using "Real Life" Example to Enhance Learning in a General Chemistry Lecture

Full text: PDF (80 K)

130
Education: Theory & Practice:
P. Galcheva, K. Vachkov
Prospective Teachers in Chemistry: Possibilities for Forming of Professional Competence

Full text: PDF (203 K)

134
Problems:
G. Pekov, D. Tasheva, P. Tsanova, H. Chanev, E. Stanoeva
2010' Entrance Exam in Chemistry at 'St. Kliment Ohridski' University of Sofia

Full text: PDF (271 K)

144
Chemistry & History of Chemistry: An Online Supplement:
B. Semire, O.A. Odunola
DFT Study on Cyclopenta-2,4-dienones and Cyclopenta-2,4-dienethiones as Dienophiles for Reactivity Prediction in Diels-Alder Reactions

Full text: PDF (205 K)

E9
 

Khimiya, Volume 20, Issue 2(2011)

Khimiya. 20, 83- (2011) Author(s): I. Kuleff:

Abstract.The present paper emphasizes on some of the scientific investigations, carried out by Marie Skłodowska-Curie, which lead to the new scientific field radiochemistry. Also in the paper are given some data from the life of Marie Curie, pointing why she is so important figure when today we speak about emancipation of women and why exactly the year 2011 is elected to be an International Year of Chemistry.

Keywords: international year of chemistry, Maria Curie, radiochemistry

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Khimiya. 20, 96- (2011) Author(s): E. Kirkova:

Abstract.The review exemplifies the stereochemistry of the p-chemical elwements with proper examples, mainly from the inorganic chemistry. These examples with their contemporary interpretation will help undergraduates and graduates when studynh inorganic or organic chemistry. The different types of atomic orbitals hybridizations are carefully examined.

Keywords: p-elements, atomic orbitals, hybridazation, sp-hybridization, sp2-hybridization, sp3-hybridization

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Khimiya. 20, 134- (2011) Author(s): P. Galcheva, K. Vachkov:

Abstract. To form of professional competence of the prospective Chemistry teachers is a task that follows both from the National Program for Modernization of Education and the National Educational Standards. Observations of students during their pedagogical practice show that they have difficulties in organizing educational activities, communication with pupils and, as a result they lack the desire for creativity and innovation. The possibilities to overcome these bad consequences of the teaching process are considered in the present article.

Keywords: citizenship education, professional competencies, environmental education, chemistry education

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Khimiya. 20, 144- (2011) Author(s): G. Pekov, D. Tasheva, P. Tsanova, H. Chanev, E. Stanoeva:

Abstract.2010 entrance exam in chemistry at "St. Kliment Ohridski" University of Sofia was held in two sessions: the first one was before the end of the school year (April, 3). This does not reduce the number of candidates, but in contrary - they were more than on the second test, which was held after the school year end (July, 10). And, despite the unusual time for the first test, the score for it was no more worse than on the second, held in much more exam time. There is no enough data for detailed comment on such result, but some resonable assumptions about it are made. Tasks of the two exams and their solutions can be found at the site of Sofia University Faculty of Chemistry, http://chem.uni-sofia.bg

Keywords: entrance exam in chemistry, test questions, logic problems

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Khimiya. 20, E9- (2011) Author(s): B. Semire, O.A. Odunola:

Abstract.The reactivity of both cyclopenta-2,4-dienones and cyclopentadienethiones were discussed with special emphasis on the use of cyclopentadienethione dienophiles in Diels-Alder type reactions. The ω values obtained for the molecules with electron-donating group (-CH3) increased the nucleophilicity power whereas substitution with electron-withdrawing groups (such as -NO2 and -CO2CH2CH3) increased the electrophilicity power, indicating an increase of reactivity towards a nucleophiles. The cyclopentadienethiones would be more reactive towards nucleophiles than the cyclopentadienone analogues due to low values of η and high values of ω. This was supported by local ionization potential energy surfaces and Mullikens charges on the cardonyl carbon and oxygen on cyclopentadienone and thienyl carbon and sulphur on cyclopentadienethiones. A relationship was established for the C-S bond and electrophicity index (ω) of cyclopentadienethiones.

Keywords: cyclopenta-2,4-dienones, cyclopenta-2,4-dienethiones, reactivity prediction

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