Neon

For other uses, see Neon (disambiguation).
General Name, Symbol, Number neon, Ne, 10 Chemical series noble gases Group, Period, Block 18, 2, p Appearance colorless
Atomic mass 20.1797(6) g/mol Electron configuration 1s2 2s2 2p6 Electrons per shell 2, 8 Physical properties Phase gas Density (0 °C, 101.325 kPa)
0.9002 g/L Melting point 24.56 K
(-248.59 °C, -415.46 °F) Boiling point 27.07 K
(-246.08 °C, -410.94 °F) Heat of fusion 0.335 kJ/mol Heat of vaporization 1.71 kJ/mol Heat capacity (25 °C) 20.786 J/(mol·K) Atomic properties Crystal structure cubic face centered Oxidation states no data Ionization energies
(more) 1st: 2080.7 kJ/mol 2nd: 3952.3 kJ/mol 3rd: 6122 kJ/mol Atomic radius (calc.) 38 pm Covalent radius 69 pm Van der Waals radius 154 pm Miscellaneous Magnetic ordering nonmagnetic Thermal conductivity (300 K) 49.1 mW/(m·K) Speed of sound (gas, 0 °C) 435 m/s CAS registry number 7440-01-9 Notable isotopes References

Neon is the chemical element in the periodic table that has the symbol Ne and atomic number 10. A colorless nearly inert noble gas, neon gives a distinct reddish glow when used in vacuum discharge tubes and neon lamps and is found in air in trace amounts.

Notable characteristics

Neon is the second-lightest noble gas, glows reddish-orange in a vacuum discharge tube and has over 40 times the refrigerating capacity of liquid helium and three times that of liquid hydrogen (on a per unit volume basis). In most applications it is a less expensive refrigerant than helium. Neon has the most intense discharge at normal voltages and currents of all the rare gases.

Applications

Neon is often used in signs

The reddish-orange color that neon emits in neon lights is widely used to make advertising signs. The word "neon" is also used generically for these types of lights when in reality many other gases are used to produce different colors of light. Other uses:

History

Neon (Greek neos meaning "new") was discovered by Scottish chemist William Ramsay and English chemist Morris Travers in 1898.

Occurrence

Neon is usually found in the form of a gas with molecules consisting of a single neon atom. Neon is a rare gas that is found in the Earth's atmosphere at 1 part in 65,000 and is produced by supercooling air and fractionally distilling it from the resulting cryogenic liquid. Neon, like water vapor, is lighter than air; unlike water vapor, which condenses into a liquid below the stratosphere and is thus trapped in Earth's atmosphere, neon may slowly leak out into space, which explains its scarcity on Earth. Argon, in contrast, is heavier than air and so remains within Earth's atmosphere.

Compounds

The ions, Ne+, (NeAr)+, (NeH)+, and (HeNe+), have been observed from optical and mass spectrometric research. In addition, neon forms an unstable hydrate.

Isotopes

Neon has three stable isotopes: 20Ne (90.48%), 21Ne (0.27%) and 22Ne (9.25%). 21Ne and 22Ne are nucleogenic and their variations are well understood. In contrast, 20Ne is not known to be nucleogenic and the causes of its variation in the Earth have been hotly debated. The principal nuclear reactions which generate neon isotopes are neutron emission, alpha decay reactions on 24Mg and 25Mg, which produce 21Ne and 22Ne, respectively. The alpha particles are derived from uranium-series decay chains, while the neutrons are mostly produced by secondary reactions from alpha particles. The net result yields a trend towards lower 20Ne/22Ne and higher 21Ne/22Ne ratios observed in uranium-rich rocks such as granites. Isotopic analysis of exposed terrestrial rocks has demonstrated the cosmogenic production of 21Ne. This isotope is generated by spallation reactions on magnesium, sodium, silicon, and aluminium. By analyzing all three isotopes, the cosmogenic component can be resolved from magmatic neon and nucleogenic neon. This suggests that neon will be a useful tool in determining cosmic exposure ages of surficial rocks and meteorites.

Similar to xenon, neon content observed in samples of volcanic gases are enriched in 20Ne, as well as nucleogenic 21Ne, relative to 22Ne content. The neon isotopic content of these mantle-derived samples represent a non-atmospheric source of neon. The 20Ne-enriched components are attributed to exotic primordial rare gas components in the Earth, possibly representing solar neon. Elevated 20Ne abundances are also found in diamonds, further suggesting a solar neon reservoir in the Earth.

References


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Elevated 20Ne abundances are also found in diamonds, further suggesting a solar neon reservoir in the Earth. According to Rebbenu Bachya, the word "Yahalom" in the verse Exodus 28:18 means "Pearl" and was the stone on the Ephod representing the tribe of Zebulun. The 20Ne-enriched components are attributed to exotic primordial rare gas components in the Earth, possibly representing solar neon. Necklaces can also be classified as uniform, where all the pearls are the same size, graduated, where the pearls are arranged in size from large in the centre to smaller at the ends, or tin cup, where pearls are generally the same size, but separated by lengths of chain. The neon isotopic content of these mantle-derived samples represent a non-atmospheric source of neon. An opera will be long enough to reach the breastbone or sternum of the wearer, and longer still, a pearl rope is any length that falls down further than an opera. Similar to xenon, neon content observed in samples of volcanic gases are enriched in 20Ne, as well as nucleogenic 21Ne, relative to 22Ne content. A matinee of pearls falls just above the breasts.

This suggests that neon will be a useful tool in determining cosmic exposure ages of surficial rocks and meteorites. The size called a princess comes down to or just below the collarbone. By analyzing all three isotopes, the cosmogenic component can be resolved from magmatic neon and nucleogenic neon. Pearl chokers nestle just at the base of the neck. This isotope is generated by spallation reactions on magnesium, sodium, silicon, and aluminium. A collar will sit directly against the throat and not hang down the neck at all, they are often made up of multiple strands of pearls. Isotopic analysis of exposed terrestrial rocks has demonstrated the cosmogenic production of 21Ne. While most other necklaces are simply referred to by their physical measurement, strings of pearls have their own set of names that characterize the pearls based on where they hang when worn around the neck.

The net result yields a trend towards lower 20Ne/22Ne and higher 21Ne/22Ne ratios observed in uranium-rich rocks such as granites. There is also a unique way of naming pearl necklaces. The alpha particles are derived from uranium-series decay chains, while the neutrons are mostly produced by secondary reactions from alpha particles. Although imitation pearls look the part, they do not have the same weight or smoothness as real pearls, and their luster will also dim greatly. The principal nuclear reactions which generate neon isotopes are neutron emission, alpha decay reactions on 24Mg and 25Mg, which produce 21Ne and 22Ne, respectively. Some imitation pearls are simply made of mother-of-pearl, coral or conch, while others are made from glass and are coated with a solution containing fish scales called essence d'Orient. In contrast, 20Ne is not known to be nucleogenic and the causes of its variation in the Earth have been hotly debated. Imitation pearls are much easier to identify by jewellers.

21Ne and 22Ne are nucleogenic and their variations are well understood. If the centre is not perfectly round, the jeweller recognises that it is genuine, and gives it a higher value. Neon has three stable isotopes: 20Ne (90.48%), 21Ne (0.27%) and 22Ne (9.25%). This is because when the cultivators insert the grit, (usually a polished piece of mussel shell), it is always pefectly round, so as to produce a more expensive, perfectly round pearl. In addition, neon forms an unstable hydrate. If the grit in the centre of the pearl is a perfect sphere, then the jeweller knows it is cultivated. The ions, Ne+, (NeAr)+, (NeH)+, and (HeNe+), have been observed from optical and mass spectrometric research. One way that jewellers can determine whether a pearl is cultivated or natural is by x-raying the pearl.

Argon, in contrast, is heavier than air and so remains within Earth's atmosphere. In general, cultivated pearls are less valuable than natural pearls, and imitation pearls are the least expensive. Neon, like water vapor, is lighter than air; unlike water vapor, which condenses into a liquid below the stratosphere and is thus trapped in Earth's atmosphere, neon may slowly leak out into space, which explains its scarcity on Earth. Ringed pearls are characterized by concentric ridges, or rings, around the body of the pearl. Neon is a rare gas that is found in the Earth's atmosphere at 1 part in 65,000 and is produced by supercooling air and fractionally distilling it from the resulting cryogenic liquid. They are also commonly seen in necklaces. Neon is usually found in the form of a gas with molecules consisting of a single neon atom. Baroque pearls have a different appeal to them than more standard shapes because they are often highly irregular and make unique and interesting shapes.

Neon (Greek neos meaning "new") was discovered by Scottish chemist William Ramsay and English chemist Morris Travers in 1898. Drop and pear shaped pearls are sometimes referred to as teardrop pearls and are most often seen in earrings, pendants, or as a center pearl in a necklace. Other uses:. Button pearls are like a slightly flattened round pearl and can also make a necklace, but are more often used in single pendants or earrings where the back half of the pearl is covered, making it look like a larger, round pearl. The word "neon" is also used generically for these types of lights when in reality many other gases are used to produce different colors of light. Semi-rounds are also used in necklaces or in pieces where the shape of the pearl can be disguised to look like it is a perfectly round pearl. The reddish-orange color that neon emits in neon lights is widely used to make advertising signs. Perfectly round pearls are the rarest and most expensive, and are generally used in necklaces, or strings of pearls.

Neon has the most intense discharge at normal voltages and currents of all the rare gases. Pearls come in eight basic shapes: round, semi-round, button, drop, pear, oval, baroque, and ringed. In most applications it is a less expensive refrigerant than helium. Irregular shaped pearls are often used in necklaces. Neon is the second-lightest noble gas, glows reddish-orange in a vacuum discharge tube and has over 40 times the refrigerating capacity of liquid helium and three times that of liquid hydrogen (on a per unit volume basis). Teardrop-shaped pearls are often used in pendants. . Large, perfectly round pearls are rare and highly valued.

A colorless nearly inert noble gas, neon gives a distinct reddish glow when used in vacuum discharge tubes and neon lamps and is found in air in trace amounts. All factors being equal, however, the larger the pearl the more valuable it is. Neon is the chemical element in the periodic table that has the symbol Ne and atomic number 10. Among those attributes, luster is the most important differentiator of pearl quality according to jewelers. Los Alamos National Laboratory – Neon. The value of the pearls in jewelry is determined by a combination of the luster, color, size, lack of surface flaw and symmetry that are appropriate for the type of pearl under consideration. Liquefied neon is commercially used as an economical cryogenic refrigerant. Cultured pearls are also produced using abalone.

Neon and helium are used to make a type of gas laser. Freshwater pearls are characterized by the reflection of rainbow colors in the luster. television tubes. In the 1990s, Japanese pearl producers also invested in producing cultured pearls with freshwater mussels in the region of Shanghai, China, and in Fiji. wave meter tubes. Japanese pearl farmers now culture a hybrid pearl mussel—a cross between the last remaining Biwa Pearl Mussels and a closely related species from China—in other Japanese lakes. lightning arrestors. Since the time of peak production in 1971, when Biwa pearl farmers produced six tons of cultured pearls, pollution and overharvesting have caused the virtual extinction of this animal.

high-voltage indicators. The extensive and successful use of the Biwa Pearl Mussel is reflected in the name "Biwa pearls," a phrase nearly synonymous with freshwater pearls in general. vacuum tubes. This lake, the largest and most ancient in Japan, lies near the city of Kyoto. In 1914 pearl farmers began culturing freshwater pearls using the pearl mussels native to Lake Biwa. Tahitian pearls (also referred to as Titian pearls) are also another South Sea pearl.

Australia is one of the most important sources of South Sea pearls. Sizes up to 14 mm in diameter are not uncommon. South Sea pearls are characterized by their large size and silvery color. One of the largest pearl-bearing oysters is the Pinctada maxima, which is roughly the size of a dinner plate.

In the past couple of decades, cultured pearls have been produced with larger oysters in the south Pacific and Indian Ocean. The original Japanese cultured pearls, known as Akoya pearls, are produced by a species of small oysters no bigger than 6 to 7 cm in size, hence Japanese pearls larger than 10 mm in diameter are extremely rare and highly priced. Oysters which survive the subsequent surgery to remove the finished pearl are often implanted with a new, larger nucleus as part of the same procedure and then returned to the water for another three years of growth. Along with a small scrap of mantle tissue from another oyster to serve as an irritant, it is surgically implanted near the oyster's genitals.

The nucleus is generally a polished bead made from mussel shell. This mariculture process was first developed by Kokichi Mikimoto in Japan, who was granted a patent for the process in 1896. The pearls are usually harvested three years after the planting, but it can take up to as long as six years before a pearl is produced. Now, however, almost all pearls used for jewelry are cultured by planting a core or nucleus into pearl oysters.

In fact, in a haul of three tonnes, only three or four oysters will produce perfect pearls. Not all natural oysters produce pearls, however. Divers manually pulled oysters from ocean floors and river bottoms and checked them individually for pearls. Before the beginning of the 20th Century, pearl hunting was the most common way of harvesting pearls.

. Black pearls, frequently refered to as Black Tahitian Pearls are highly valued because of their rarity; the culturing process for them dictates a smaller volume output due to rejection by the oysters. Pearls are usually white, sometimes with a creamy or pinkish tinge, but may be tinted with yellow, green, blue, brown, purple, or black. The iridescence that some pearls display is caused by the overlapping of successive layers, which breaks up light falling on the surface.

The unique luster of pearls depends upon the reflection and refraction of light from the translucent layers and is finer in proportion as the layers become thinner and more numerous. This combination of calcium carbonate and conchiolin is called nacre, or as most know it, mother-of-pearl. As a response to an irritating object inside its shell, the mollusk will deposit layers of calcium carbonate (CaCO3) in the form of the minerals aragonite or calcite (both crystalline forms of calcium carbonate) held together by an organic horn-like compound called conchiolin. Pearls are formed inside the shell of certain bivalve mollusks.

Pearl is valued as a gemstone and is cultivated or harvested for jewellery. A pearl is a hard, rounded object produced by certain mollusks, primarily oysters.

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