Atoms, Chains and Crystals Backstage

Seeing Atoms Before the Show

1Every spring, the stage crew at Hollis Valley Middle School builds the set and runs the lights for the school musical. Their adviser, Mr. Farid Nazari, also teaches science. During a long rehearsal, he opened a free molecule viewer on a tablet. The viewer draws computer models of the particles in a substance, and crew chief Keala Kahananui and lighting assistant Theo Marchetti used it to look at the materials around the stage.

2The viewer has two modes. In ball-and-stick mode, each atom is a small ball and each bond that joins two atoms is a stick, so you can see which atoms are joined to which. In space-filling mode, the atoms are drawn as larger balls that touch. This shows the overall shape of a particle but hides the bonds. Each kind of atom gets its own color. A chemical formula lists the atoms in a substance, and a small number after a symbol tells how many of that atom there are.

3The crew started with gases. Some older stage lamps have a thin tungsten wire inside a glass bulb filled mostly with argon gas, which helps the hot wire last longer. The viewer showed argon as single balls that were never joined to anything, and it showed the helium in the balloons for the finale the same way. The air in the theater is a mixture. In a sample of air, about 78 of every 100 particles are nitrogen molecules (N₂), about 21 are oxygen molecules (O₂) and about 1 is an argon atom.

4Next they looked at the stage itself. The fog machine heats a fluid that is mostly water and glycerin. The dance floor is covered with vinyl, a plastic made of very long chains. In each chain, a unit of 2 carbon atoms, 3 hydrogen atoms and 1 chlorine atom (C₂H₃Cl) repeats thousands of times in a row, and each chain has two ends. The lamp's tungsten wire and the silicon chips in the lighting board looked different again. When Theo zoomed out, the atoms kept repeating in the same pattern in every direction until they reached the edges of the sample.

5For the opening scene, an adult crew member wearing thick gloves drops dry ice, which is solid carbon dioxide, into warm water to make low fog. The viewer showed the dry ice as CO₂ groups, each with 1 carbon atom joined to 2 oxygen atoms. The groups were lined up in a repeating pattern, with small gaps between neighboring groups and no sticks joining one group to the next. Keala recorded what the viewer showed for five materials in Table 1, and Mr. Nazari added each melting point from a reference book.