VSEPR structures of CO2 and determine the point groups and identify all symmetry elements present
The Correct Answer and Explanation is:
The VSEPR structure of carbon dioxide (CO2) is determined by considering its Lewis structure and applying the Valence Shell Electron Pair Repulsion (VSEPR) theory. The Lewis structure of CO2 shows that the carbon atom is double-bonded to two oxygen atoms (O=C=O). Since the carbon atom is central and the oxygen atoms are on either side, the molecular geometry is linear with a bond angle of 180 degrees.
VSEPR structure of CO2:
- The carbon atom is surrounded by two bonding regions (the O=C double bonds).
- There are no lone pairs of electrons on the central carbon atom, which further supports the linear geometry.
- The oxygen atoms also have two lone pairs each.
Now, let’s analyze the symmetry:
Point group of CO2:
The point group of CO2 is D2h. This is a high symmetry group that applies to molecules with a linear geometry and a center of symmetry. CO2 belongs to this group due to its symmetry elements.
Symmetry elements of CO2:
- E (Identity): The molecule has the identity operation, meaning it remains unchanged.
- C2 (Twofold rotation axis): CO2 has two C2 axes. One is along the molecular axis (z-axis), and the other is perpendicular to the molecule (in the xy-plane).
- i (Inversion center): The CO2 molecule has an inversion center at the carbon atom. This means if you invert the molecule through the center, it remains unchanged.
- σh (Horizontal mirror plane): The horizontal mirror plane cuts through the carbon atom and is perpendicular to the molecular axis.
- 2 σv (Vertical mirror planes): There are two vertical mirror planes, each containing the molecule’s main axis, symmetrically dividing the two oxygen atoms.
In summary, the symmetry elements of CO2 include identity, C2 axes, inversion center, and mirror planes, all of which contribute to its D2h point group.
