Reason behind the fireworks

Red, white and blue fountains or bursts of purple sparks, each firework is packed with just the right mix of chemicals to create these colourful lights.
Inside each firework is something called an aerial shell — a tube that contains gunpowder and dozens of small modules called "stars," These stars hold fuel, an oxidizing agent, a binder and metal salts or metal oxides — the source of the firework's hues. A time-delay fuse ignites the gunpowder and bursts the aerial shell once the firework is midair, causing the stars to scatter and explode far above the ground, producing a shower of light and colour. Once exposed to fire, the stars' fuel and oxidizing agents generate intense heat very rapidly, activating the metal-containing colourants. When heated, atoms in the metal compounds absorb energy, causing their electrons to rearrange from their lowest energy state to a higher "excited" state. As the electrons plummet back down to their…