How can atoms emit light

Light Properties. Electromagnetic Spectrum. Emission and Absorption. Field Spectroscopy. Photoelectric Effect. Field Spectroscopy First Draft.

Greenhouse Gases. Lewis Dot Structures. Polarity, Dipoles, and Bonds. Molecular Shapes. Molecular Vibrations. Gapminder Statistics - BMI. Oxidation-Reduction Reactions. Atoms and molecules can absorb and emit light, telling us how many different energy levels an electron has and how far apart the energy levels are spaced.

Different colors of light are associated with different photon energies. Essentially, a photon is a packet of light. However, the energy absorbed and released when the electron moves between the second and fourth shells is x 10 m, which is in the visible range.

Since this emission signature is unique for each element, looking at the colors of other stars, or the tops of the atmospheres of other planets, is a good way of identifying the elements in them.

You can also do flame tests to identify different elements. The wavelength of light emitted for the movement of an electron between the electron shells of a hydrogen atom is given by the Rydberg formula :. You must be logged in to post a comment. Skip to content Emission and absorption spectrum of Hydrogen. Image adapted from the one by Wikimedia Commons User:Adrignola. An oxygen atom with two electrons in the innermost shell and six in the second shell.

Orbitals describe the possible places around the atom where an electron can be and different ones have both different shapes and different energies. To understand this you need a fair dose of quantum mechanics. But the only part that is really relevant here is that those different orbitals have lots of different possible energies. Mostly the electrons will be in the lowest energy orbitals. But when you heat things up in a flame some of them will get enough extra energy to be boosted into higher energy orbitals.

When they lose that extra energy, they emit the lost energy as a photon of a particular colour. Now the complicated bit. Because there are a lot of possible orbitals those electrons or that single electron in the case of a hydrogen atom, other atoms usually have more than one electron , there are a lot of possible transitions that can happen. But excited hydrogen atoms can crudely show emissions from any higher level to any lower level. So, because there are a lot of possible energy levels for electrons to occupy, there are a lot of possible colours of emission from even the simplest atom.

And most atoms have more than one electron so the options are even larger. Your simple intuition that the pattern of emission from other atoms would be easily explained is wrong. A lot of emission lines are well outside the visible so the lines you can actually see are not a good indicator for all the emissions that can happen.

Even hydrogen with just one electron is complicated. But the key idea is that there are many possible energy levels electrons can occupy and therefore many possible "colours" of emitted light. Sign up to join this community. The best answers are voted up and rise to the top.

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Why do atoms emit a certain colour of light? The emission spectra Ask Question. Asked 2 years, 8 months ago. Active 8 months ago. Viewed 9k times. Improve this question. Indeed, comparing the similarities of atoms was how the table was designed originally. Also, there needs to be certain attention to detail - e. Add a comment. Active Oldest Votes. As an example, this is what the spectrum for hydrogen looks like, which is broken up into a number of different spectral series : Image source Generally speaking, the emission spectra of most atoms cover roughly similar wavelength ranges, basically spreading over the visible range with substantial bleed over into the UV and infrared regions.

But you can still ask a very similar question, by inserting an appropriate plural: what determines the colours of light emitted? Improve this answer. Emilio Pisanty Emilio Pisanty k 28 28 gold badges silver badges bronze badges. To summarize: Each atom has many orbitals that its electrons can occupy, and the energies of these orbitals vary from atom to atom. You cleared up a lot!