Hypervalent molecules

Definition

Hypervalent molecules are species in which a central atom forms more than four bonds or has more than eight electrons in its valence shell. These molecules defy the octet rule, common examples include sulfur hexafluoride (SF_6) and phosphorus pentachloride (PCl_5).

5 Must Know Facts For Your Next Test

1. Hypervalent molecules typically involve elements from periods 3 and beyond on the periodic table.
2. The formation of hypervalent molecules is often explained by the use of d-orbitals for expanded valence shells.
3. Common examples include SF_6, PCl_5, and XeF_4.
4. These molecules can be understood using concepts from Molecular Orbital Theory as well as Valence Shell Electron Pair Repulsion (VSEPR) theory.
5. Hypervalency is often seen in nonmetallic compounds where the central atom forms more than an octet to achieve stable electron configurations.

Review Questions

Related terms

Octet Rule:

A chemical rule that reflects observation that atoms tend to combine in such a way that they each have eight electrons in their valence shells.

Valence Shell Electron Pair Repulsion (VSEPR) Theory:

A model used to predict the geometry of individual molecules based on the repulsion between electron pairs around a central atom.

Molecular Orbital Theory: A method for determining molecular structure in which electrons are not assigned to individual bonds between atoms but are treated as moving under the influence of nuclei in the whole molecule.