Tonight while watching the sky light up with colored streamers, star bursts and smiley faces, you will be watching chemistry in action.

The gunpowder that launches aerials out of their cardboard tubes is a mixture of saltpeter (potassium nitrate), carbon and sulfur. All three are commonly occurring minerals that are inert individually.

When combined and given an activation energy, a reaction begins that will rapidly oxidize the carbon and sulfur to carbon dioxide and sulfur dioxide. For every oxidation reaction there is an equal and opposite reduction reaction.

When gunpowder burns, saltpeter is reduced to potassium and nitrogen as oxygen atoms migrate from nitrate ions to carbon and sulfur atoms, releasing heat that was stored as potential energy in the chemical bonds. When gunpowder is burned in a confined space, the gases produced cannot expand, so pressure builds until something gives. In an aerial light show the explosion propels a carefully packed projectile of chemical potential energy high into the air.

At the top of its trajectory, an enclosed timer triggers a second explosion that scatters artistically patterned arrangements of glowing, color-producing chemical marbles. These are made of metal salts that vary depending on the desired color.

Nitrate oxidants such as saltpeter can only produce a temperature of about 3,100 degrees Fahrenheit, which is not hot enough to energize the metallic salts that produce the bright colors in the aerial displays. To get the full range of colors, potassium perchlorate replaces the saltpeter. Oxygen atoms in perchlorate ions are more energetically bonded to chlorine atoms than to the nitrogen in nitrates and contain more potential energy per molecule. The resulting temperature of just over 3,600 degrees Fahrenheit is enough to energize electrons in the metal atoms, causing them to jump to higher quantum levels.

Metals that are used in fireworks all have one or two electrons in their outermost shell. An energized electron makes a series of quantum jumps up a steplike energy ladder as it gains energy. Eventually it will fall back down the ladder and give up energy equal to the number of steps in the jump as a photon, a quantum of light of a particular frequency.

The frequency of a quantum of light is proportional to its energy, and we perceive frequency as color of different wavelengths. White light is a mixture of all wavelengths between 400 and 700 nanometers, the normal range of our vision.

Every chemical element has a ladder with a unique pattern of steps that produces a uniquely spaced spectral fingerprint of specific frequencies for that element as its energized electrons de-energize.

Neon lights operate on this principle. Different colored neon lights are tubes that are filled with different low-pressure gases and energized with high-voltage electricity to glow with a characteristic spectrum.

Our eyes are not spectrographs. We see the combined frequencies of all of the electron transitions as a particular color: violet from potassium, blue or green from copper, yellow from sodium, bright red from strontium or lithium, and so on for different metals and their salts.

There is a lot more than meets the eye in those aerial pyrotechnics.

Richard Brill is a professor of science at Honolulu Community College. His column runs on the first and third Fridays of the month. Email questions and comments to brill@hawaii.edu.