Why do expanded octets form

Related Terms main group element hypervalent molecule. Examples of expanded octet in the following topics: The Expanded Octet Main group elements in the third period and below form compounds that deviate from the octet rule by having more than 8 valence electrons. As a result, the second period elements more specifically, the nonmetals C, N, O, F obey the octet rule without exceptions. Therefore, the d orbitals participate in bonding with other atoms and an expanded octet is produced.

Examples of molecules in which a third period central atom contains an expanded octet are the phosphorus pentahalides and sulfur hexafluoride. For atoms in the fourth period and beyond, higher d orbitals can be used to accommodate additional shared pairs beyond the octet. Table of Geometries If the central atom possesses partially occupied d-orbitals, it may be able to accommodate five or six electron pairs, forming what is sometimes called an " expanded octet.

The formulas written here neutralize this charge separation by double bonding that expands the valence octet of sulfur. In this way sulfur may expand an argon-like valence shell octet by two e. Oxidation States of Phosphorus Compounds In this way phosphorus may expand an argon-like valence shell octet by two electrons e.

Boron compounds such as BH3 and BF3 are exceptional in that conventional covalent bonding does not expand the valence shell occupancy of boron to an octet. A hypervalent molecule is a molecule that contains one or more main group elements that bear more than eight electrons in their valence levels as a result of bonding.

As a result, the second period elements more specifically, the nonmetals C, N, O, F obey the octet rule without exceptions. However, some of the third-period elements Si, P, S, and Cl have been observed to bond to more than four other atoms, and thus need to involve more than the four pairs of electrons available in an s 2 p 6 octet. Although the energy of empty 3d-orbitals is ordinarily higher than that of the 4s orbital, that difference is small and the additional d orbitals can accommodate more electrons.

Therefore, the d orbitals participate in bonding with other atoms and an expanded octet is produced. Examples of molecules in which a third period central atom contains an expanded octet are the phosphorus pentahalides and sulfur hexafluoride. What is the upper limit on what an atom can have around it in a Lewis structure?

Any insight is appreciated. Re: An explanation of expanded octets? For instance, elements can have expanded octets. Xenon can hold 14 electrons because it has an f subshell, which contains 7 orbitals, each capable of holding 2 electrons. Hope this helps. Post by devenpatel2O » Thu Oct 30, am Thanks for your answer. Yes that helps. But are you saying a metal in the 3rd period or higher 4th, 5th