A neon light that is entirely filled with neon gas emits a brilliant red-orange hue. The various colors produced by other neon lights are due to a mixture of other chemical elements, such as argon, helium, krypton, xenon and mercury.
One of the most familiar applications of neon is in advertising, where neon lights are incorporated in display billboards. Traditionally, neon lights or signs are fashioned using plastic or glass tubes that are filled with neon gas at low pressure. The tubes are then electrically induced where high-energy electrons bombard neon atoms to produce the characteristic red-orange emission. In modern times, neon lights are made using various elements. The corresponding colors for neon lights filled with xenon, helium, argon, krypton and mercury vapor are gray or blue-gray, orange white, lavender, gray-green and light blue, respectively.