Question

Why does an atom produce a discontinuous-spectra \[?\]

Answer 1

Hint: We now know that atoms are made up of protons, neutrons and electrons. Electromagnetic spectrums classify into continuous spectrum and discontinuous spectra. A continuous spectrum contains every wavelength between the wavelength on which the spectrum starts and the wavelength on which the spectrum ends. A discontinuous spectrum is a spectrum that contains gaps, holes, or breaks in terms of the wavelengths that it contains.

Complete answer:
Atomic spectra also known as line spectra. Atomic spectra are discontinuous because the energy levels of electrons in atoms are quantized. The electrons in an atom can have only certain energy levels. There is no middle ground. If an electron is excited to a new energy level, it jumps to that level instantaneously.

When it returns to a lower level, it releases energy in a quantized packet. This release occurs in the form of light of a specific wavelength (colour). Hence, atomic emission spectra represent the electrons returning to lower energy levels. Each packet of energy corresponds to a line in the atomic spectrum. There is nothing between each line, so the spectrum is discontinuous.

The main difference is that line spectra can be seen as either isolated emission lines or absorption lines, with huge gaps between them, whereas continuous spectra do not contain gaps and can be produced by superimposing the emission and absorption spectra of the same.

Note: Continuous spectra also called thermal or blackbody spectra. It arises from dense gases or solid objects which radiate heat. They emit radiation over a broad range of wavelengths thus the spectra appear smooth and continuous. Emission spectra are discontinuous atomic spectra as the light is emitted only at a certain wavelength with dark spaces between them and absorption spectra are continuous atomic spectra as a continuum of radiation is passed through a sample which absorbs radiation of specific wavelength.