What is the electron geometry of CO
2
?
The Correct Answer and Explanation is :
The electron geometry of carbon dioxide (CO₂) is linear. To determine this, let’s analyze its molecular structure based on the principles of valence shell electron pair repulsion (VSEPR) theory, which predicts the shape of a molecule based on electron pairs around the central atom.
Step-by-Step Explanation
- Count Valence Electrons:
- Carbon (C) has 4 valence electrons.
- Oxygen (O) has 6 valence electrons, and since there are two oxygen atoms, we have (2 \times 6 = 12) electrons.
- Therefore, CO₂ has a total of (4 + 12 = 16) valence electrons.
- Draw the Lewis Structure:
- Carbon is the central atom because it has the lowest electronegativity among the atoms.
- We place two double bonds between carbon and each oxygen atom to satisfy the octet rule (each atom achieves a stable configuration with eight electrons around it).
- This gives us the Lewis structure: O=C=O.
- Determine Electron Domains:
- In VSEPR theory, we consider the electron domains (regions of electron density) around the central atom. Each double bond counts as one electron domain.
- Carbon in CO₂ has two electron domains, corresponding to the two double bonds with each oxygen atom.
- Identify the Electron Geometry:
- With two electron domains around the central atom, VSEPR theory predicts a linear geometry to minimize repulsion.
- A linear geometry has a bond angle of 180° between the atoms.
- Molecular Shape:
- Since CO₂ has no lone pairs on the central atom (carbon), its electron geometry and molecular geometry are the same: linear.
Thus, the electron geometry of CO₂ is linear due to its two electron domains, resulting in a straight-line shape with bond angles of 180°.