Which of the following best describes an electron domain in the context of electron geometry?

• A. The total number of valence electrons in a molecule.
• B. The area occupied by only nonbonding electrons on an atom.
• C. A region around a central atom where electrons are likely to be found, including both bonding pairs and lone pairs.
• D. A single covalent bond between two atoms.

Answer: (C)

Verified step by step guidance

1. Understand that an electron domain refers to a region around a central atom where electrons are most likely to be found.
2. Recognize that electron domains include both bonding pairs (shared electrons in covalent bonds) and lone pairs (nonbonding electrons localized on the atom).
3. Note that electron domains are not just single bonds or only lone pairs, but any area where electron density is concentrated around the central atom.
4. Recall that the concept of electron domains is fundamental in determining the electron geometry of a molecule, which considers all electron pairs around the central atom.
5. Therefore, the best description of an electron domain is: 'A region around a central atom where electrons are likely to be found, including both bonding pairs and lone pairs.'