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Xenon (Xe)

QUICK REFERENCE

  • Symbol: Xe
  • Atomic Number: 54
  • Atomic Weight: 131.293
  • Element Classification: Noble Gas
  • Discovered By: Sir William Ramsay and Morris M. Travers
  • Discovery Date: 1898
  • Name Origin: Greek: ‘xenos’ (stranger)
  • Density(g/cc): 0.005887 (gas at 0°C, 101.325 kPa)
  • Melting Point: -111.8°C
  • Boiling Point: -108.1°C
  • Appearance: Colorless, odorless gas
  • Atomic Radius(pm): 108

Discovery

Xenon was discovered in 1898 by Scottish chemist Sir William Ramsay and English chemist Morris M. Travers in London, England. Following their discoveries of neon, krypton, and argon, they isolated xenon from the residue left after liquid air had been fractionally distilled to remove other noble gases. The discovery was part of their groundbreaking research on atmospheric gases, which greatly expanded the understanding of the noble gases. Xenon was named after the Greek word ‘xenos’, meaning stranger, reflecting its rare and exotic nature.

Relation to Other Elements

Xenon is a member of the noble gases, located in group 18 of the periodic table. It is heavier than neon, argon, and krypton, and precedes radon. Noble gases are characterized by their extremely low chemical reactivity, due to having full valence electron shells. However, xenon is notable among the noble gases for its ability to form chemical compounds, including fluorides and oxides, under certain conditions.

Natural Occurrence

Xenon is a trace gas in the Earth’s atmosphere, making up about 0.0000087% (87 parts per billion by volume) of the air. It is obtained commercially through the fractional distillation of liquefied air, a process that also yields other noble gases. Due to its low abundance, xenon is relatively expensive compared to other gases obtained from the air.

Uses

Despite its rarity, xenon has several important applications:

  • Lighting: Xenon is used in powerful lamps, including flash lamps for photography, high-intensity discharge lamps for car headlights and projectors, and in light sources for endoscopy.
  • Anesthesia: Xenon gas is used as a general anesthetic. Its use in anesthesia benefits from xenon’s low solubility in blood, making recovery faster compared to other anesthetics.
  • Nuclear Energy: Xenon-135, a radioactive isotope of xenon, has a significant impact on the operation of nuclear reactors due to its high neutron absorption cross-section, acting as a neutron absorber or “poison” that can affect reactor control.
  • Space Propulsion: Xenon is used as a propellant in ion thrusters for spacecraft, favored for its high atomic mass and low ionization potential, which make it efficient for this purpose.
  • Imaging: Hyperpolarized xenon is used in magnetic resonance imaging (MRI) to enhance imaging of lungs and other biological tissues.

The discovery of xenon and the subsequent development of xenon chemistry have illuminated the complexities and potential reactivity of noble gases, challenging the notion that these elements are completely inert. Xenon’s unique properties and applications underscore the diversity of uses for noble gases in science and industry.

Iodine (I)

Cesium (Cs)