Neon (chemical symbol Ne, atomic number 10) is one of the six naturally occurring noble gases found on the periodic table. Neon exists in a gaseous state at typical room temperatures because it possesses extremely weak intermolecular forces between its atoms. This state is maintained until the temperature drops to its very low boiling point.
Why Neon is Classified as a Noble Gas
Neon’s gaseous state and lack of chemical reactivity are a direct result of its atomic structure. Positioned in Group 18 of the periodic table, neon is a noble gas defined by having a completely filled outer electron shell. This stable configuration of eight valence electrons satisfies the octet rule, giving the neon atom exceptional stability.
Because the atom’s electron shell is already complete, neon has virtually no tendency to gain, lose, or share electrons with other atoms. This stability makes neon chemically inert, meaning it resists forming molecular bonds or compounds under normal conditions. Consequently, neon remains a monatomic gas, where its molecules consist of single, unbonded neon atoms. Its high ionization potential further strengthens its resistance to forming chemical compounds.
Physical Properties and Origin
Neon is an invisible, odorless, and tasteless gas. It is the second-lightest noble gas, after helium, and has a density that is about two-thirds that of air. Neon’s resistance to liquefaction is notable, as it has an extremely low boiling point of approximately -246.08°C (-410.94°F). The range of temperature between its boiling point and its freezing point is the narrowest of any element, only about 2.5°C.
Although neon is the fifth most abundant element in the universe, it is relatively rare on Earth. Its lightness and chemical inertness prevented it from being trapped in the dust clouds that formed our planet. Neon makes up only about 0.0018 percent of the Earth’s atmosphere by volume. Commercial neon is separated from the atmosphere as a byproduct of the fractional distillation of liquid air.
Common Uses of Neon
The most recognizable application of neon is in illuminated signage, commonly called “neon signs.” When a high voltage electrical current is passed through neon gas sealed in a glass tube, the atoms become excited and emit a distinctive, bright reddish-orange light. This phenomenon, called electroluminescence, makes the gas useful for advertising and display lighting. The light is also known for its ability to penetrate fog, making it useful in specialized aircraft lighting.
Beyond lighting, liquid neon is used in specialized cooling applications, known as cryogenics. Neon excels as a refrigerant due to its low boiling point and high cooling capacity. On a per-unit-volume basis, liquid neon provides a refrigerating capacity about 40 times greater than liquid helium, making it an efficient choice for cooling sensitive equipment. Neon is also used in high-voltage indicators and combined with helium to create certain types of lasers.