Neon and the Noble Gases
Neon was discovered in 1898 by William Ramsey and M.W. Travers. Neon is classified as a noble gas, along with argon, xenon, radon, helium and krypton. Noble gases are non-reactive and stable.
Neon was the first gas used to make light, which is why all gas-filled tubes are now called neon lights. These gas-filled tubes can last between 8 and 15 years. Neon lights are used primarily as neon signs, although they are also used for decoration; some people put neon lights under their cars or use them as nightlights under the beds of children. The very first neon sign used for advertising in the United States was introduced in 1925.
Neon signs can contain as many colors as the designer wants, using a combination of straight gas, mixed gases and elements, colored glass tubing and fluorescent tubing. Each letter or element of the sign is made separately and kept sealed from the rest of the sign. This allows many different colors to exist in one sign.
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How Neon Lights Work
When an electrical currant is applied to a neon light tube the atoms belonging to the gas are knocked out of their orbit. The free electrons collide with each other and are sent back to the atoms. As the free electrons are absorbed by the atoms they produce energy. This energy produces the light.
How Neon Lights Get Their Color
Each gas used in neon lights has its own color. Neon is red, helium is orange, argon is lavender, krypton is gray or green, mercury vapor is light blue, and xenon is gray or blue. Mixing gases and elements added to a neon light creates different hues. Baking fluorescent powders onto the inside walls of the glass tubes also modifies the colors and shades of the finished neon sign. Colored glass tubes are also used for the same effect.