Structure
Xenon difluoride is a linear molecule with an Xe–F bond length of 197.73±0.15 pm in the vapour stage, and 200 pm in the solid phase. The packing arrangement in solid XeF2 shows that the fluorine atoms of neighbouring molecules avoid the equatorial region of each XeF2 molecule. This agrees with the prediction of VSEPR theory, which predicts that there are 3 pairs of non-bonding electrons around the equatorial region of the xenon atom.
At high pressures, novel, non-molecular forms of xenon difluoride can be obtained. Under a pressure of ~50 GPa, XeF2 transforms into a semiconductor consisting of XeF4 units linked in a two-dimensional structure, like graphite. At even higher pressures, above 70 GPa, it becomes metallic, forming a three-dimensional structure containing XeF8 units. However, a recent theoretical study has put these experimental results in doubt.
Read more about this topic: Xenon Difluoride
Famous quotes containing the word structure:
“The philosopher believes that the value of his philosophy lies in its totality, in its structure: posterity discovers it in the stones with which he built and with which other structures are subsequently built that are frequently better—and so, in the fact that that structure can be demolished and yet still possess value as material.”
—Friedrich Nietzsche (1844–1900)
“One theme links together these new proposals for family policy—the idea that the family is exceedingly durable. Changes in structure and function and individual roles are not to be confused with the collapse of the family. Families remain more important in the lives of children than other institutions. Family ties are stronger and more vital than many of us imagine in the perennial atmosphere of crisis surrounding the subject.”
—Joseph Featherstone (20th century)
“When a house is tottering to its fall,
The strain lies heaviest on the weakest part,
One tiny crack throughout the structure spreads,
And its own weight soon brings it toppling down.”
—Ovid (Publius Ovidius Naso)