Hypervalent molecule  From Wikipedia, the free encyclopedia Jump
to: navigation, search  A hypervalent molecule (the phenomenon
is sometimes colloquially known as expanded octet) is a molecule
that contains one or more main group elements formally bearing
more than eight electrons in their valence shells. Phosphorus
pentachloride (PCl5), sulfur hexafluoride (SF6), chlorine
trifluoride (ClF3), and the triiodide (I3) ion are examples of
hypervalent molecules.  Definitions and nomenclature[edit]
Hypervalent molecules were first formally defined by Jeremy I.
Musher in 1969 as molecules having central atoms of group 15–18
in any oxidation state other than the lowest.[1]  Several
specific classes of hypervalent molecules exist:  N-X-L
notation[edit]  N-X-L nomenclature, introduced in 1980,[3] is
often used to classify hypervalent compounds of main group
elements, where:    • N represents the number of valence
electrons   • X is the chemical symbol of the central atom   • L
the number of ligands to the central atom