Why do different chemicals emit different colors of light, and why is the color emitted specific to that chemical?

Every chemical is made up of atoms and each atom has one or more electrons surrounded its nucleus. The electron emits light after changing from a high energy state o to a lower energy state which is known as transition. The color of this light is unique to each element because each atom of a particular element has a different transition energy.

it forms an anion that has a larger radius. anions have a negative charge and are larger than the original atom.