We are all familiar with the bright advertisement hoardings, shining bright during the night in big cities. In the early 20th century, night skies were always illuminated by these brilliant red-orange neon lights. From revolutionizing the idea of advertisement to diverse fashion culture, neon has always been a centre of interest to humanity. It was in the late summers of 1898, when two British chemists, W. Ramsay and M. W. Travers, discovered neon, along with krypton and xenon, by condensing dry air and capturing the residual gases. Like many other chemical elements, the name neon is also derived from a Greek letter “Neos,” which means something new.
Neon Light hoardings in a City
Neon is a chemical element in the periodic table with the symbol (Ne) and atomic number 10. It is placed in the 18th group (noble gases) and the 2nd period of the Periodic table. It is the second lightest noble gas. Although it is known to be the fifth most abundant element in the universe (only hydrogen, helium, oxygen, and carbon are more abundant), it only constitutes 18.2 parts per million of air by volume in the earth’s atmosphere. Neon’s high volatile and inert nature is the reason for its scantiness on the earth. Even the inner terrestrial planets such as, mercury, venus, earth, and mars, face the scarcity of neon in their atmosphere.
Isotopes
Neon has three stable isotopes, _{ }^{ 20 }{ Ne }(90.48%), _{ }^{ 21 }{ Ne }(0.27%) ,and _{ }^{ 20 }{ Ne }(9.25%). _{ }^{ 20 }{ Ne } is the key isotope of neon due to its abundance in the universe. Its origin goes back to the very beginning of the universe, i.e., Big Bang, while _{ }^{ 21 }{ Ne } and _{ }^{ 22 }{ Ne } can also be synthesized in a nuclear reaction after neutron capture and immediate emission of the alpha particles.
Three stable Isotopes of neon
Neon, along with xenon, can also be found in the samples taken from volcanic gases. They represent the magmatic isotope content of neon present on the earth.
Magmatic inert gases
Occurrence
The key stable isotope of neon, _{ }^{ 20 }{ Ne }, is formed in stars during the carbon-burning process of stellar nucleosynthesis (the process of creating new atomic-nuclei from the pre-existing ones). During the carbon-burning process, two atoms of carbon fuse together under very high temperature and pressure conditions to form Neon, along with helium nuclei.
Neon is monoatomic in nature, due to which it is lighter than the other diatomic gas molecules in the air. Therefore, it can rise above other gases in the atmosphere and escape from it. However, a neon balloon would escape the atmosphere a little bit slower than that of helium.
Properties of Neon
Neon is a colorless, odorless, inert noble gas, though it gives off a bright red-orange colored light when applied inside a discharge tube, under normal voltages and currents.
1. Physical Properties
Neon present in the earth’s atmosphere generally exists in a gaseous state. The most interesting fact about neon is that it has a very narrow temperature range to exist in the liquid phase. It changes from a gas to a liquid at -245.92°C (-410.66°F) and from a liquid to a solid at -248.6°C (-415.5°F)
Phase Diagram of Neon.
The density of neon is 0.00089994 gram per cubic centimeter at 273.15K under standard atmospheric pressure conditions.
2. Chemical Properties
Neon is the first p-block noble gas with electronic configuration 1s2 2s2 2p6. It’s also the first element to have a complete octet in the periodic table. Like all other noble gases, neon is also chemically inactive, or inert in nature. Because of their full valance shells, all the noble gases has extremely low reactivity. But unlike helium, neon is slightly soluble in water.
Neon can form a very weak bond to a transition metal atom as a ligand, for example, Cr(CO)5Ne, Mo(CO)5Ne, and W(CO)5Ne. Neon does not, generally, form solid compounds, but under extremely high vacuum pressure of 480 Mpa, and temperature of around 70K, it forms a special kind of hydrates, known as Clathrate Hydrates.
Clathrate Hydrates formed at high pressure.
Neon can also form Van Der Waal molecules on the account of weak London dispersion forces, such as CCl4Ne, Ne2Cl2, Ne3Cl2.
Uses of Neon
Neon has various industrial applications that have transformed our everyday life from time to time. Let’s discuss a few of its uses
1. Neon Lights
The most familiar and impactful application of neon is neon light. Contrary to popular misconception, not all neon lights contain neon, most of them are mixtures of other elements also. Neon emits light only in bright red-orange color. This idea revolutionized the advertisement industry in the early 20th century, by providing easy to get noticed neon-color-based hoardings, though this technology was replaced by the introduction of LEDs, LCDs, and other display techniques.
Neon bulbs are also used in greenhouses and botanical gardens to stimulate plant growth as they have been proved to increase chlorophyll content in plants.
Neon discharge tubes are also used as high voltage indicators. Neon is also used in the manufacturing of many security devices, such as lightning arresters, which grounds a massive amount of electricity if a bolt of lightning strikes a building or a tower.
Arresters used in Power Grids.
2. Cryogenics
Neon generally has a boiling point of 27.24K, which makes it a very efficient coolant; moreover, its cooling application is 40 times better than that of the liquid helium. Liquid neon is a much better alternative to liquid helium because it costs far less than helium. In comparison to hydrogen, helium is non-reactive in nature, which makes it a better replacement for machinery where chemical interactions can be a risk.
3.Lasers
Neon Helium (HeNe) lasers are widely used across the globe by researchers. These lasers are very cost-efficient and emit laser between the infrared and visible regions of light. More often, these lasers are used to emit a very specific red light of wavelength 638.2 nm.
He-Ne laser emitting bright red light.
When we apply a voltage across a discharge tube containing helium and neon mixture, helium atoms get excited to a metastable energy level. During their collision with neon atoms in the discharge tube, they can efficiently transfer that energy to neon atoms. When a sufficient number of neon atoms get excited by these collisions, population inversion takes place, and the light inside the tube gets amplified. This amplified light is known as a laser.
Health Effects of Neon
There are no direct toxic properties of neon, but it can act as an asphyxiant like other inert gases.
If neon leaks into the air, it begins to displace oxygen in the air, and it is hard to identify such leak as neon is a colorless and odorless gas. As oxygen levels fall, people can experience dizziness and respiratory problems.
If people do not evacuate in time, they can lose consciousness and die of asphyxiation from the lack of oxygen in the air. In extreme cases, this can happen in a matter of minutes before the realization of a leak.