[Chemistry Class Notes] on Xenon Pdf for Exam

Xenon is the chemical element, with the symbol Xe, which is an extreme and rare heavy gas of Group 18 (noble gases) of the periodic table. This was the first noble gas, which is found to form true chemical compounds. It is more than 4.5 times heavier than air, odourless, tasteless, and colourless. Solid xenon belongs to the cubic crystal system of face-centred, which implies that its molecules, consisting of single atoms, behave as spheres, which are packed together possibly closely. The term xenon is derived from the Greek word Xenos, which means “foreign” or “strange.”

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Properties of Xenon

Xenon occurs in very few traces as gases within the Earth and exists to the extent of up to 0.0000086 percent, or up to 1 part in 10 million by volume of dry air. Same as several other noble gases, xenon is also present in meteorites. Xenon can be manufactured on a small scale based on the fractional distillation of liquid air. It is the least volatile (with a boiling point, −108.0 °C) if the noble gases are obtainable from the air.

The element xenon can be used in lamps which produce extremely intense and short flashes of light, like stroboscopes and lights for high-speed photography. When an electrical charge is passed through the gas at low pressure, it emits a bluish-white light flash; at higher pressures, white light resembling daylight is emitted. Flash lamps of xenon can be used to activate ruby lasers.

Compounds

After the discovery that xenon can form chemical compounds by Neil Bartlett in 1962, a huge count of xenon compounds has been discovered and also described. Mostly all the known xenon compounds have the electronegative atoms oxygen or fluorine. The chemistry of xenon in every oxidation state is analogous compared to the neighbouring element iodine in the immediately lower oxidation state.

Halides

Three known fluorides, which are given as XeF2, XeF4, XeF6. XeF is the one, which is theorized to be unstable. These are the starting points for almost all xenon compound synthesis.

The crystalline and solid difluoride (XeF2) is produced when a mixture of xenon and fluorine gases is exposed to ultraviolet light. The ultraviolet component of the ordinary daylight is adequate—Heating XeF2 in long-term at higher temperatures under a NiF2 catalyst yields XeF6. XeF6 pyrolysis in the presence of NaF yields XeF4 with high-purity.

Oxides and Oxohalides

Three oxides of xenon are known: xenon tetroxide (XeO4) and xenon trioxide (XeO3), (both dangerously powerful and explosive oxidizing agents) and xenon dioxide (XeO2), reported in 2011 with a coordination number of four. XeO2 produces when the xenon tetrafluoride is poured over ice. Also, its crystal structure can allow it to replace the silicon in silicate minerals. The cation, XeOO+ has been identified by infrared spectroscopy in the solid argon.

Xenon does not directly react with oxygen, and the trioxide is produced by the hydrolysis of XeF6:

XeF6 + 3 H2O → XeO3 + 6HF

XeO3 is given as weakly acidic, dissolving in the alkali metal to form unstable xenate salts that contain the HXeO−4 anion. These unstable salts disproportionate to xenon gas and perxenate salts easily, which contain XeO4−6 anion.

Clathrates and Excimers

In addition to the compounds, in which xenon produces a chemical bond, xenon can produce the clathrates substances, in which xenon pairs or atoms are trapped by the crystalline lattice of the other compound. An example is given as xenon hydrate (Xe·​5 3⁄4H2O), where xenon atoms occupy vacancies in a lattice of water molecules. This clathrate contains a melting point of 24 °C.

This hydrate’s deuterated version has also been produced. Another example is xenon hydride (Xe(H2)8), where xenon pairs (which are dimers) are trapped inside the solid hydrogen. Such clathrate hydrates may occur naturally under the conditions of high pressure, like in Lake Vostok underneath the Antarctic ice sheet. The clathrate formation is used to distil krypton, xenon, and argon fractionally.

Applications

Let us look at the use of xenon in various applications.

Gas-discharge lamps: Xenon can be used in light-emitting devices, which are called xenon flash lamps, that can be used in stroboscopic lamps and photographic flashes; to excite the active medium in lasers and then generate coherent light, and in bactericidal lamps, occasionally. The first solid-state laser, which was invented in 1960, pumped by lasers and a xenon flash lamp, used to power inertial confinement fusion are also pumped by the xenon flash lamps.

A group of researchers at Bell Laboratories discovered laser action in xenon in 1962, and later it was found that the laser gain was improved by adding the helium to the medium of lasing. The first excimer laser, which is a xenon dimer (Xe2) energized by an electrons beam to form stimulated emission at an ultraviolet wavelength of 176 nm. Xenon fluoride and xenon chloride have also been used in the excimer (or, exciplex, more accurately) lasers.