The concepts of electronegativity and classical electronegativity scales are briefly described. Electronegativity scales have practical quantitative applications, and this work suggests activities which can assist students select the scales for use in chemistry applications. It provided examples of the use of an appropriate electronegativity…

In chemical synthesis, obtaining product(s) with high purity is a crucial issue from both academic and industrial viewpoints. Higher purity of the product(s) means higher quality and a lower chemical production costs. Sometimes, purification and separation processes are very laborious and lead to significant impacts on the final price of the…

Bounded by the statements of Feynman and Galileo, I describe certain tricks that can be useful for the teaching of physics. In particular, I describe the calculation of the center of mass (centroid) of an arc of circumference and a circular sector. For this purpose, I also use Pappus's theorems. An Appendix is available with Archimedes' method to…

In this paper, we propose a novel method for deriving Russell-Saunders terms of complex atomic systems with an arbitrary number of equivalent electrons in orbitals with a higher azimuthal number. The method can be regarded as an extension of the classic works of Douglas, McDaniel, and Hyde but with several notable improvements, including the…

By organizing an extracurricular seminar, based on the analysis of the intermolecular dispersion action in normal alkanes, a new topological index (named "Intermolecular Interaction Index (IMI)") was proposed to express the intermolecular dispersion force. The IMI has an excellent linear relationship with the boiling point (T[subscript…

One of the greatest challenges in a student's ability to successfully complete reactions in organic chemistry is the ability to differentiate between reactions that have similar structures and proceed through similar reaction mechanisms. Featured in this article is an interleaved reaction review activity called a reaction web. Students are divided…

A laboratory experiment has been designed for teaching laboratories aimed at training students in the basics of spectroscopy in junior and senior level undergraduate chemistry courses. Despite the ubiquity of light-based tools in modern science, students often find it difficult to comprehend light and light-matter interactions. A portable…

The UV--vis absorption of cyanine dyes is a common experiment in many physical chemistry teaching laboratories. As part of the analysis, students are often asked to hypothesize why the predicted absorption differs from the measured values and why dyes which are predicted to have the same absorption have measured values which differ from each…

In school chemistry, the oxyhydrogen or "Knallgas" reaction is used to provide evidence of hydrogen gas in the squeaky pop test. However, the test actually indicates the presence of an explosive gas mixture of hydrogen and oxygen (oxyhydrogen gas) rather than pure hydrogen. The sheer observations of an explosive reaction and the…

The emerging field of genomic medicine offers an opportunity for biology and anatomy teachers to bring the topics of DNA, genetics, molecular processes, and evolution together into one experience. Through the genomic medicine paradigm, students see the unbroken connection between small biological topics such as mutations and their potential…

A simple, safe, and easy demonstration of the reaction of sodium peroxide with water is presented. The reaction is performed in a plastic bottle by adding water to sodium peroxide supported in a rubber "thimble"; oxygen is detected by the reignition of a glowing splint, while the generation of sodium hydroxide is indicated by…

In nature, we often observe interesting phenomena for which we would like to find a physical explanation. One such phenomenon is presented in this paper.

The Physics Teacher has published over the years many inspiring papers with an historical slant and we agree with Thomas B. Greenslade, who recently wrote that teaching physics is about "integrating physics with human culture.… if we are going to leave a lasting impact on our students, we should do more than teach them pure physics."…

DNA-functionalized gold nanoparticles (DNA-AuNPs) have become a popular science theme since their invention in 1990s. They impact our daily lives by playing key roles in rapidly identifying and quantifying important analytes, and are a well-suited chemistry course content for beginners of chemical research. While the salt-aging method represents…

The preparation of ethyl acetoacetate is a distinctive, century-old classic organic chemistry laboratory project. Ethyl acetate and sodium metal (sodium ethoxide) are reacted by Claisen ester condensation to produce the sodium salt of ethyl acetoacetate and then obtain the refined product by acidification as well as washing, drying, and…