Valence shell electron pair repulsion theory (VSEPR) as explained in most textbooks predicts that substituents bonded to a central atom in AX[subscript n]E[subscript z][superscript c] species (A = main-group central atom, X = substituent, E = lone pair on central atom, c = charge) will change their X-A-X angles to bend away from the lone pairs.…

The fundamental principles and applications of thermodynamics and single-component phase equilibrium are used to explain and quantitatively analyze the operation and performance of the vapor-compression refrigerator (VCR). Carbon dioxide is used as the refrigerant. The four processes (or steps) that comprise the VCR refrigeration cycle are…

Many statistical methods (estimators) are available for estimating the consensus value (or average effect) and heterogeneity variance in interlaboratory studies or meta-analyses. These estimators are all valid because they are developed from or supported by certain statistical principles. However, no estimator can be perfect and must have error or…

We have developed a curriculum for the organic chemistry laboratory in which students draw on authentic usage of spectroscopy, spectrometry, and computational chemistry to explain chemical phenomena. This curriculum, which has been continuously refined over a decade, has been explored by many thousands of students and is scalable to small and…

One of the main topics of elementary physics is the idea that every material is composed of "little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one other." These particles could be atoms or molecules. Atoms are the smallest part into…

The concept of an atom with an expanded octet, known as hypervalency, has persisted in the general chemistry curriculum, despite abundant theoretical work disputing its veracity. Here, the electronic structure of traditionally hypervalent molecules (H[subscript 2]SO[subscript 3], H[subscript 2]SO[subscript 4], PF[subscript 5], and SF[subscript 6])…

A significant approach that should be followed by physics teachers at the secondary education level in order to enhance students' understanding is to highlight the generality of the mathematical procedures that describe different physical phenomena. In this paper, the common procedure that is used to calculate the duration of various physical…

In general, undergraduate experimental physics laboratories do not usually have experiments designed to address rolling friction and to measure the value of the rolling friction coefficient. This work explores an experiment, which has the potential to arouse students' curiosity about rolling friction by addressing a counterintuitive aspect of the…

We look at the problem of the minimum speed of projectiles in a constant gravitational field. In the absence of resistance, the problem may be studied in the frame of a high school curriculum. One needs only Newton's laws and a minimum amount of analytic geometry to compute the orbit, which turns out to be parabolic. Furthermore, in case the…

Equilibrium is an essential concept in undergraduate physics curriculum as it integrates Newton's laws and torque. The importance also comes from its wide applications in mechanics and biomechanics. Simulations of Back and Arms are developed mainly for the undergraduates who major in physical therapy and health sciences. They are implemented as…

Prediction of number of [Pi]-bonds, [sigma]-bonds, single and triple bonds of aliphatic unsaturated open-chain and cycloalkynes is a vitally important tool for students of chemistry at undergraduate and graduate level for solving different kinds of problems regarding different chemical reactions. In this manuscript, we try to present a simple and…

This "Science note" arose out of practical work involving the dilution of ethanoic acid, the measurement of the pH of the diluted solutions and calculation of the acid dissociation constant, K[subscript a], for each diluted solution. The students expected the calculated values of K[subscript a] to be constant but they found that the…

In undergraduate E&M courses the magnetic field due to a finite length, current-carrying wire can be calculated using the Biot-Savart law. However, to the author's knowledge, no textbook presents the calculation of this field using the Ampere-Maxwell law: ?B [multiplied by] dl = µ[subscript 0] (I + e[subscript 0] dF/dt) [multiplied by] 1

Students often wrestle unsuccessfully with the task of correctly calculating momentum probability densities and have difficulty in understanding their interpretation. In the case of a particle in an "infinite" potential well, its momentum can take values that are not just those corresponding to the particle's quantised energies but…

The advantages of Gaussian-type orbitals (GTO) over Slater-type orbitals (STO) in quantum chemistry calculations are clarified here by means of a holistic approach. The popular Microsoft Office Excel program was used to create an interactive application with which students are able to explore the features of GTO, including automatic calculations…