David’s Discovery: The chemistry behind fireworks

ROCHESTER, Minn. (KTTC) – Each year on the Fourth of July we are in awe of the beautiful colors that fill our dark skies when fireworks are set off. Did you ever wonder how these magnificent colors form? Meteorologist David Burgett traveled to Rochester Technical Community College (RCTC) to learn about the chemistry behind fireworks. Dr. Heather Sklenicka, a Chemistry Professor, said the science is based on various elements.

"As you will probably see on the Fourth of July there are a ton of different colors that can show up in fireworks and you ooh and you ahh," she said. "But when a chemist looks at it it's like strontium, sodium, and tin. Yay!"

Sklenicka explained that the science behind the colors we witness involves electrons. Protons are ps that have a positive charge, while electrons have a negative charge. Electrons orbit around the nucleus, or the center of an atom. Protons are confined to the nucleus.

"When metals bond they actually lose electrons," she said. "There are more protons in the nucleus than there are electrons in the electron cloud ."

Sklenicka further said when metals or elements are in an environment of higher energy, a color will eventually be given off. The color is not the result of a chemical reaction but is based on the metal's physical properties.

"When those metals have positive charges and interact with a lot of energy their electrons move around and that's what creates the colors," Sklenicka said.

Electrons will move up energy levels when they are in an environment of higher energy like in the demonstration with a Bunsen burner's flame. You can think of energy levels as different stages where an electron is allowed to exist or orbit around the nucleus. An increase in energy will allow the electron to move up energy levels.

"The electrons start at a ground state, they absorb some of the heat from the flame and they go into an excited state," she said.

Sklenicka emphasized after the electrons lose energy they return to the lowest energy level or ground state. As they do energy will be released as visible light. In the experiment, the metals strontium, tin, and copper were used to simulate the vibrant colors seen in fireworks. Strontium turned the color red, copper turned green, while a tin compound turned a bright flakey orange similar to a sparkler. The combination of copper and strontium showed an eye-catching combination of red and green too.

I hope you learned something new today, have a safe and happy Fourth of July weekend!