by E. Garrone, C.O. Areán and B. Bonelli
Communication
This paper replies to two of the most common questions that students usually pose to their teacher during a general chemistry course, i.e. how many chemical elements are in the Periodic Table and how many could be in our Universe. Reply to the former question can be easily found either in the literature or in any updated chemistry book. More interestingly, this communication shows that the latter question may be (simply) answered by making reference to the Bohr’s atomic model that, notwithstanding its well-known limits, allows teachers to demonstrate that (for a hydrogenoid atom) 137 is the highest possible value for Z, as predicted by quantum electrodynamics, a much more complicated theory, usually taught in Physics advanced courses.
World Journal of Chemical Education. 2017, 5(1), 20-22. DOI: 10.12691/wjce-5-1-4
Pub. Date: February 27, 2017
11042 Views3258 Downloads
by C.C. Giac, N.T.P. Lien and P.N. Tuan
Original Research
This paper introduces the way to solve some inorganic chemistry exercises by using the graphic method of calculation for teaching chemistry in high school. We have divided them into 7 types of exercise involving in the use of graphs to find the solution methods.Based on these ways, the authors have built 9 Sample Problems. On that basis, the authors compiled 15 drilling exercises for Test Yourself which are used for teaching and self-studying inorganic chemistry in High School.
World Journal of Chemical Education. 2017, 5(1), 12-19. DOI: 10.12691/wjce-5-1-3
Pub. Date: February 07, 2017
13156 Views2388 Downloads23 Likes
by Francisco Sánchez-Viesca and Reina Gómez
Letter To Editor
Nitration of pyridine N-oxide gives 4-nitropyridine N-oxide. This is an abnormal nitrone reactivity involving an electronic back-donation. However, the textbooks treat this result in a very brief way, without any insight. Which are the experimental antecedents of this reaction? What theory was proposed to explain them? What reactivity is overturned by these proposals? How theory and practice can come to agree on this subject? All these questions will be treated and answered in this communication.
World Journal of Chemical Education. 2017, 5(1), 9-11. DOI: 10.12691/wjce-5-1-2
Pub. Date: January 22, 2017
12414 Views2793 Downloads
by Diego J. R. da Silva
Original Research
A general formalism for defining and identifying limiting reagent in closed systems is proposed and it is correlated to usual definitions and identification methods. An alternative definition of limiting reagent is proposed, based on real situations after the reaction is complete. Useful equations relating the limiting reagent to products and excess reagents (if the limiting reagent is completely consumed or not) and to reaction yields are given and briefly applied.
World Journal of Chemical Education. 2017, 5(1), 1-8. DOI: 10.12691/wjce-5-1-1
Pub. Date: January 21, 2017
14170 Views4971 Downloads2 Likes