Why are transition metals used to make fireworks?

Answer 1

The short answer is "because of the emission spectrum of the metal in question".

When metal atoms are heated strongly, they emit light of a characteristic color, due to the atom's emission spectrum (this depends somewhat on the other atoms in the compound, but generally speaking this is a minor effect, shifting it from one shade of red to a slightly different shade of red rather than shifting it from red to blue).

The particular metal salt used depends on what color you want the fireworks to be. For orangish-yellow, sodium salts work well; for red, you can use strontium salts, etc.

Answer 2

Firework factories put metals into their firework, because metals are seriously reactive. Most of these fireworks have a specific metal called Bologni.

Answer 3

Their ions (produced by the burning of the fireworks) emit a wide variety of different colors of light.