Neon is gas. Resourceful engineers invented neon lamps, and in the 20s of the 20th century neon signs conquered the whole world.
The true color of neon
When we think about neon, we imagine the names of shops and restaurants glowing with different colors. In fact, neon glows with a bright, red - orange light. A rich range of colors is achieved by introducing mercury and sodium vapor into the gas lamps. In Las Vegas, the streets are brightly lit with curved gas pipes inviting tourists to play casinos or listen to Wayne Newton's singing.
How is neon mined?
Neon is contained in the atmosphere, so maybe at that moment, you breathe in a little bit of neon. Do not worry, there is so little neon in one liter of air that it is not enough to fill a grain of popcorn. To separate neon from air, air has to be liquefied. Just like water, when it changes from a vapor to liquid state upon cooling, air turns into a liquid when the temperature decreases. Only with water does this happen at 100 degrees Celsius, and with neon at minus 246 degrees Celsius - this is exactly the boiling point of neon. Liquid neon is separated from other components of the air. During liquefaction, neon is obtained in a mixture with nitrogen and helium.
By increasing the temperature and pressure of the mixture, chemists remove nitrogen from it. Helium is removed using a process called adsorption. In this case, gas molecules precipitate on solids.Neon molecules adhere better to the surface of activated carbon than helium molecules. This property of them is used to separate the mixture. To get one kilogram of neon, you need to process 88,000 kilograms of air.
Why is neon glowing?
If you pour cold liquid neon into a glass, you can see that it is transparent and colorless - in any case, there is no hint of a bright red color. Why, then, in advertising does neon glow brightly in different colors? The neon pumped into the tubes consists of billions and billions of atoms. Each neon atom has ten electrons in orbit around the nucleus. Both ends of the neon tube are connected to an electrical circuit.
When the current is turned on, it passes along the tube: the electrons jump from atom to atom, as it should be when the current passes. Neon atoms are excited in a collision with electrons in the same way as a person who was roughly pushed in a crowd. The electrons in the neon atom are not prone to vagrancy, therefore, after excitation, the atom calms down and the electron returns to its place. As a result, an atom emits a photon of light. The energy of these photons lies in the red part of the spectrum of visible light.
Colors of other gases
Other gases emit photons of other colors when excited. For example, mercury vapor, which contains 80 electrons in an atom, emits blue light when excited. The difference between blue and red light is the difference in photon energy. Photons emitted by a mercury atom have a higher energy than photons of neon atoms. Sodium lamps used for highway lighting emit a bright yellow light. Its photons are more energy intensive than red light photons, but less energy intensive than blue photons.
When an electric current flows through a neon tube, some atoms are excited (in a collision with electrons), while others remain in a normal unexcited state. Then they change places. Each atom looks like a flickering light bulb: one blinks, then another. As a result, we perceive a neon tube glowing with a steady light. When the current turns off, neon comes into its usual state, that is, it becomes colorless.
