Introductory Chemistry Laboratory: Quantum Mechanics and Color

Abstract

Laboratory experiments provide students a tangible means of understanding dry, abstract concepts. A simple and engaging introductory wet chemistry laboratory has been developed relating quantum mechanics to color, which has been implemented for a class of about 600 students per academic year for over three years at Brown University. Color is an important aspect of daily life, used to communicate meaning and emotion. Nanoparticles, organic dyes, and metal complexes produce color in medieval stained glass, textiles, and gemstones, respectively. Though they can produce visually similar colors, the microscopic mechanisms of color production are different. The origins of color are used to facilitate the discussion of quantum mechanics and bonding concepts. The relation of these color producing model systems to chemical concepts also serves as motivation for an introduction of advanced concepts, such as nanochemistry, to first-year undergraduate students. Students synthesize silver nanoparticles of different shapes and sizes and use UV–vis spectrophotometers to characterize them along with additional unknown colorful solutions made from either metal complexes or organic dyes. Relating quantum mechanics and bonding to color in daily life excited students, promoting learning. This laboratory can be adapted for K–12 students.

Utilizing Yellow Compounds to Introduce π-Conjugated Molecular Structures: A Harmony with Blue Compounds

“…Colorful experiments are generally delightful, − with yellow compounds often being used in chemistry education, − especially carotenoids, which are among the most ubiquitous pigments. , This lesson also starts with carotenoids and spotlights species found in natural gardenia fruits and marigold flowers, which are familiar in everyday life. To make the yellow stand out, the complementary color blue was simultaneously displayed to students.…”

Exploring the Role of Transition Metal Complexes in Artistic Coloration through a Bottom-Up Scientific Approach

“…Transition metals, not bound to any ligands, have electrons occupying 5 degenerate d-orbitals. Yet this is altered when involving ligands in a coordination complex, causing some of their d-orbitals to energetically shift and become nondegenerate [5]. This phenomenon, called d-orbital splitting, is the most common coloration mechanism for transition metal complexes [34].…”

“…Despite the extensive usage of these pigments, the nuanced exploration of the precise mechanisms underlying their coloration is a more modern pursuit. It has been recognized that their vibrant colors are the visual manifestations of d-orbital splitting, ligand field theory, and charge transfer [3,[5][6][7][8] features inherent to the transition metal complexes within the pigment. These complexes are not fixed, however, and their constitutions can be altered by various environmental factors and interactions [9][10][11][12], therefore altering the visual light wavelengths they absorb and reflect [13].…”

Exploring the Role and Variability of 3d Transition Metal Complexes in Artistic Coloration through a Bottom-Up Scientific Approach

“…Transition metals, as free ions, have electrons occupying five degenerate d-orbitals. Yet this is altered when involving ligands in a coordination complex, causing some of their d-orbitals to energetically shift and become nondegenerate [5]. Consequently, valence electrons can transition from lower-energy d-orbitals to those of higher energy when subjected to radiation [19].…”

“…Despite the extensive usage of these pigments, the nuanced exploration of the precise mechanisms underlying their coloration is a more modern pursuit. It has been recognized that their vibrant colors are the visual manifestations of d-orbital splitting, ligand field theory, and charge transfer [3,[5][6][7][8] features inherent to the transition metal complexes within the pigment. These complexes are not fixed, however, and their constitutions can be altered by various environmental factors and interactions [9][10][11][12], therefore altering the visual light wavelengths they absorb and reflect [13].…”