How many electron domains does CO have?
The Correct Answer and Explanation is :
In the molecule carbon monoxide (CO), there are two electron domains around the carbon atom.
Explanation:
- Understanding Electron Domains: In molecular geometry, an electron domain refers to regions where electron density is concentrated around an atom. These regions could include lone pairs (non-bonding electrons) or bonds (single, double, or triple bonds) with neighboring atoms. Each bond, regardless of whether it’s single, double, or triple, is considered a single electron domain in terms of geometry.
- Structure of CO: In carbon monoxide, carbon and oxygen are joined by a triple bond. CO has the following electron configuration:
- Carbon has 4 valence electrons, and oxygen has 6 valence electrons, making a total of 10 electrons to distribute between the two atoms.
- Carbon and oxygen form a triple bond, involving six electrons between them.
- Additionally, there is a lone pair of electrons on the oxygen atom.
- Counting Electron Domains: For determining electron domains around carbon:
- The triple bond between carbon and oxygen is considered one electron domain because the entire bonding region counts as a single domain, regardless of the number of bonds within it.
- There are no lone pairs on carbon (the lone pair is only on oxygen). Therefore, carbon has only one bonding region (the triple bond to oxygen) and no lone pairs, so it has two electron domains in total: one for the bonding region and one for the bond pair between the atoms.
- Molecular Geometry: With two electron domains around carbon, CO has a linear molecular geometry. This linear arrangement minimizes electron repulsion, aligning with the principles of Valence Shell Electron Pair Repulsion (VSEPR) theory. Thus, CO is a linear molecule with a bond angle of 180°.