Description of the Element Xenon

Physical Characteristics

• Xenon is a rare gas that occurs in concentrations of only 5 parts per trillion in the Earth's atmosphere. In its natural state, it is colorless, odorless and tasteless. However, when activated by electricity in a vacuum tube, it glows a brilliant violet-blue. In most instances, xenon is inert, non-toxic and stable. However, under extreme circumstances it can form explosive compounds.

Atomic Characteristics

• The element xenon has 54 protons and an equal number of electrons and neutrons. It occurs in period 5 and group 8A on the Periodic Table, reflecting its five electron levels and its eight outer electrons. Its electron shells account for most of the element's 216 picometer diameter, but only a negligible portion of its average atomic weight of 131.3 atomic mass units. Xenon also has 50 known isotopes, which contain between 56 and 93 neutrons. Of these, only nine are stable.

Reactivity

• Xenon's highest electron level, or valence shell, contains eight electrons, the maximum number possible for that shell. As a result, it only rarely forms chemical bonds, earning it a place among the noble, or inert, gases. However, under extreme conditions, xenon does form compounds, particularly with oxygen and fluorine. Because these compounds require so much energy to create and maintain, they are often unstable and highly toxic. Xenon trioxide, for example, is a strong oxidizing agent and an explosive.

Uses

• Manufacturers use xenon in high-luminance lamps, neutron and x-ray counters, bubble chambers, medical imaging instruments and ion thrusters for space crafts, such as NASA's Deep Space 1. Perhaps its most familiar use is in the violet-blue "neon" lights that illuminate many city streets. Manufacturers of expensive automobiles, such as BMW, Mercedes and Cadillac, often offer xenon headlamps as an option on their vehicles because they are much brighter than traditional halogen bulbs.