College of Marine Sciences & Maritime Studies

Lighting Up The Sky: The Chemistry Behind America’s Birthday

Texas A&M-Galveston Professor Grace Townsend explains the science behind the sparkle of Independence Day fireworks
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On Friday, fireworks will illuminate skies around the nation in celebration of Independence Day. This long-standing American tradition is more than just spectacle—it’s chemistry in action, with precise chemical formulations ensuring both safety and brilliance in every burst. 

Grace Townsend, director of chemistry labs at Texas A&M University at Galveston and instructional associate professor in the College of Marine Sciences and Maritime Studies, explained the science behind the dazzle. 

Grace Townsend
Professor Grace Townsend

According to Townsend, all fireworks—from hand-held sparklers to large aerial shells—share the same essential components: an oxidizer, a fuel source and metal salts that produce color. When heated, these metal salts emit light at specific wavelengths, creating the different colors and vibrant hues we see in the sky.

Townsend outlined several commonly used metal salts and their corresponding colors:

  • Strontium carbonate for red
  • Calcium compounds for orange
  • Sodium compounds for yellow (similar to sodium streetlights)
  • Barium chloride for green
  • Copper compounds for blue
  • Potassium or a strontium-copper mix for purple

“These colors appear because the heat excites the electrons in the metal atoms,” Townsend explained.  “As the electrons return to their lower energy level, or ground state, they release excess energy in the form of visible light, with each metal producing a different wavelength.”

A binding agent holds the components together, while a fuse is added to ignite the firework. The firework’s shape in the sky is determined by the timing of ignition, and the arrangement of its components.

“Fireworks are a great example of applied chemistry,” said Townsend. “It’s wonderful to see millions of Americans come together to watch a show of chemical reactions.”

Colorful fireworks over Galveston's Pleasure Pier with the Texas A&M University Galveston Campus mark in the top left hand corner
Fireworks over Galveston Island’s Historic Pleasure Pier

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Taylor Bounds
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