ballandstick

Ball-and-stick models are a type of molecular model used to visualize the three-dimensional arrangement of atoms within a molecule. In these models, balls represent atoms and sticks represent chemical bonds, giving a clear view of connectivity and the overall geometry around central atoms.

The balls are usually color-coded by element, with common conventions such as carbon in gray or black, hydrogen white, oxygen red, nitrogen blue, sulfur yellow, and halogens green or another distinct color. The sticks or rods connect the balls to imply single, double, or other bonds. In many teaching sets, the lengths and angles are approximate rather than exact, prioritizing recognizability of molecular structure over precise geometry.

Ball-and-stick models are widely used in education to illustrate molecular shapes, bond angles, hybridization concepts, and stereochemistry. They help students recognize common geometries such as linear, trigonal planar, tetrahedral, trigonal bipyramidal, and octahedral arrangements, and to understand how atoms connect within larger molecules. They are often discussed in contrast to space-filling models, which portray the relative sizes and surfaces of atoms but obscure internal connectivity.

Construction methods vary: physical kits use interconnected spheres and rods or pins, sometimes with magnets or snap-fit joints. Digital representations in software programs render ball-and-stick visuals from structural data files (for example PDB or CIF formats), allowing interactive manipulation and exploration.

Limitations include potential deviations from real bond lengths and angles, a focus on connectivity over electron distribution, and a lack of depiction of molecular surfaces or dynamics. Nevertheless, ball-and-stick models remain a foundational teaching tool for introducing molecular structure.