Atomic Theory

Light and Emission Spectrum

What does this have to do with electrons? We're getting there.

Scientists had begun to classify elements based on the unique spectral lines that the elements produced. Regardless of the location or treatment of the different elements, the same spectral lines were always produced. For example, Johann Balmer studied the spectral lines of the element hydrogen.

When a tube containing hydrogen (or other gas samples) are subjected to electrical energy, the tube emits a characteristic color. The color can then be split into the corresponding colors by the use of a prism. Scientists commonly use an instrument called a spectroscope to separate the colors seen for each element into their corresponding wavelengths of light.

The wavelengths shown above for hydrogen are always found. When all of the spectral lines are considered together, an element has a characteristic emission spectrum (or bright-line spectrum). Each element has its own unique combination of these spectral lines and therefore its own emission spectrum.

Click here to see the emission spectra of other elements. Be sure to click "emission" in the center of the Periodic Table!