The Chemistry of Fireworks Colors

Chemistry is a fascinating subject and is happening around us every day. When you understand how chemistry is involved in everyday life you will have a deeper understanding of all the processes that occur around you. We've all seen fireworks in lovely colors and effects but have you ever stopped to think how those wonderful colors are produced? To understand the chemistry of fireworks colors you will need knowledge of the structure of atoms and how electrons behave when they absorb energy. Are you ready to learn about how the colors are produced when a firework is ignited?

The chemistry of fireworks colors

Let's start with the basic structure of the atom. Every atom has a nucleus that contains protons which are positively charged with negatively charged electrons in orbitals around the nucleus. The number of protons is equal to the number of electrons so that the atom overall is neutral. Now electrons will be in the lowest energy orbital that is possible to be stable. This will be the orbital closest to the nucleus. Let's take lithium as an example. Lithium is the third element in the periodic table and has three protons and three electrons. Two electrons are in an orbital close to the nucleus. This orbital can only hold two electrons as it is has a small radius. So the third electron goes in an orbital a bit farther away from the nucleus. We say that lithium has an electronic configuration of 2,1. An electronic configuration is just a way of saying where the electrons are!

Now there are lots more orbitals further away from the nucleus that are empty in the case of lithium. They are higher in energy as they are further from the pull of the nucleus so an electron would need more energy to stay in those orbitals. If we give that one lone electron some energy, for instance in the form of heat, then it can jump from it's orbital into a higher orbital. Once there it is unstable and falls back to its original starting point. However, when it falls back it has to lose that extra energy and it does this in the form of light. The light is emitted and the wavelength of the light depends on the difference between the energies of the starting and finishing orbitals. These will be different for different metals so the wavelength of the light will be different. For lithium the main transition that occurs emits light that is red. Other metals emit light as shown below.

Sodium -------- yellow/orange

Potassium -------- lilac

Calcium -------- brick red

Barium -------- light green

Copper -------- blues

So we can use metals in fireworks that, when they absorb energy from the burning charcoal, emit light of different colors. Other metals that can be added are magnesium which emits a brilliant white light, and aluminum and titanium which also produce white light and increase the temperature at which the firework burns.

So now, when you see a fireworks display you will know how those colors are produced. Knowing the science behind everyday events doesn't spoil the enjoyment but increases it. How much more fascinating to know exactly what is happening and still be able to be in awe at the wonderful events that happen around us everyday.