What is the molecular geometry of carbon dioxide, CO₂?
bent
linear
tetrahedral
trigonal pyramidal
not enough information
The Correct Answer and Explanation is :
The molecular geometry of carbon dioxide (CO₂) is linear.
Explanation:
Molecular geometry is determined by the arrangement of atoms in a molecule and the presence of lone pairs of electrons around the central atom. In the case of CO₂, the molecule consists of one carbon atom double-bonded to two oxygen atoms.
- Lewis Structure: To understand the geometry, we first draw the Lewis structure. Carbon has four valence electrons, while each oxygen has six. In CO₂, carbon shares two of its electrons with each oxygen, forming two double bonds. This results in a total of four bonding pairs (two for each C=O bond) and no lone pairs on the carbon atom.
- Electron Domain Geometry: The presence of two double bonds around the central carbon atom means that there are two regions of electron density. According to VSEPR (Valence Shell Electron Pair Repulsion) theory, these regions will arrange themselves as far apart as possible to minimize repulsion. For two regions of electron density, the electron domain geometry is linear.
- Bond Angles: In a linear geometry, the bond angle between the two oxygen atoms and the carbon atom is 180 degrees. This is consistent with the arrangement we observe in CO₂.
- Polarity: Although CO₂ has polar bonds (C=O), the linear arrangement causes the dipoles to cancel each other out, resulting in a nonpolar molecule overall.
In summary, CO₂ exhibits a linear molecular geometry due to the arrangement of double bonds and the absence of lone pairs on the central carbon atom. This configuration leads to a 180-degree bond angle, illustrating the basic principles of molecular shape and electron arrangement.