Atomic line
spectra are another example of quantization. When an element or ion is
heated by a flame or excited by electric current, the excited atoms emit
light of a characteristic color. The emitted light can be refracted by a
prism, producing spectra with a distinctive striped appearance due to
the emission of certain wavelengths of light.
For the
relatively simple case of the hydrogen atom, the wavelengths of some
emission lines could even be fitted to mathematical equations. The
equations did not explain why the hydrogen atom emitted those particular
wavelengths of light, however. Prior to Bohr's model of the hydrogen
atom, scientists were unclear of the reason behind the quantization Light emitted or absorbed by single atoms contributes only very little
to the colours of our surroundings. Neon signs (or other gas discharge
tubes) as used for advertising, sodium or mercury vapour lamps show
atomic emission; the colours of fireworks are due to it. The aurora
borealis (northern light) is very rare at our latitudes, and to
appreciate the colours of cosmic objects, powerful telescopes are
necessary.
Neon, which gives red colour in a gas discharge, is a colourless gas. If
the light of the sun is spread out into different colours by a simple
glass prism, the narrow absorption lines cannot be seen.
of atomic emission spectra.
of atomic emission spectra.
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