The noble gases (Group 18) are located in the far right of the periodic table and were previously referred to as the "inert gases" due to the fact that their filled valence shells (octets) make them extremely nonreactive.
The Chemical Properties
Noble gases are odorless, colorless, nonflammable, and monotonic gases that have low chemical reactivity.
Atomic Number
Element
Number of Electrons/Shell
2
Helium
2
10
Neon
2,8
18
Argon
2,8,8
36
Krypton
2,8,18,8
54
Xenon
2,8,18,18,8
86
Radon
2,8,18,32,18,8
The full valence electron shells of these atoms make noble gases extremely stable and unlikely to form chemical bonds because they have little tendency to gain or lose electrons. Although noble gases do not normally react with other elements to form compounds, there are some exceptions. Xe may form compounds with fluoride and oxide.
Example 1: Xenon Fluorides
Xenon Difluoride (\(XeF_2\))
Dense white crystallized solid
Powerful fluorinating agent
Covalent inorganic fluorides
Stable xenon compound
Decomposes on contact with light or water vapor
Linear geometry
Moisture sensitive
Low vapor pressure
Xenon Tetrafluoride (\(XeF_4\))
Colorless Crystals
Square planar geometry
Discovered in 1963
Xenon Hexafluoride (\(XeF_6\))
Strongest fluorinating agent
Colorless solid
Highest coordination of the three binary fluorides of xenon (\(XeF_2\) and \(XeF_4\))
Formation is exergonic, and the compound is stable at normal temperatures
Readily sublimes into intense yellow vapors
Structure lacks perfect octahedral symmetry
Example 2: Xenon Oxide
Xenon Tetroxide (XeO4)
Yellow crystalline solid
Relatively stable
Oxygen is the only element that can bring xenon up to its highest oxidation state of +8
Two other short-lived xenon compounds with an oxidation state of +8, XeO3F2 and XeO2F4, are produced in the reaction of xenon tetroxide with xenon hexafluoride.
Example 3: Radon Compounds
Radon difluoride (RnF2) is one of the few reported compounds of radon. Radon reacts readily with fluorine to form a solid compound, but this decomposes on attempted vaporization and its exact composition is uncertain. The usefulness of radon compounds is limited because of the noble gas's radioactivity. The longest-lived isotope, 222Ra, has a half-life of only 3.82 days.