what is the emission spectrum of an element?

The emission spectrum of an element is the set of specific wavelengths or frequencies of electromagnetic radiation emitted by the element's atoms or molecules when their electrons transition from a higher energy level to a lower energy level. Each transition releases a photon whose energy corresponds exactly to the difference between the two energy states. This causes a unique pattern of bright lines—known as the emission spectrum—that acts like a fingerprint for identifying the element. The emission spectrum is observed as discrete bright lines against a dark background, each line representing a photon emitted at a specific wavelength or frequency. This uniqueness allows spectroscopy to identify elements in unknown substances by analyzing their emission spectra.