How Do Fireworks Get Their Colours?

Fireworks colours come from metal salts packed into "stars" — small pellets inside the firework shell. When the shell explodes and the stars ignite, the metal atoms are heated to thousands of degrees, causing their electrons to jump to higher energy levels. As the electrons fall back down, they emit photons of specific wavelengths (colours) characteristic of each element. Strontium compounds produce red, barium salts make green, copper compounds create blue (the most difficult colour to achieve), sodium produces bright yellow, and magnesium or aluminium generate white. Mixing compounds creates intermediate colours: strontium + copper = purple, barium + sodium = lime green.