Draw the Lewis structure of carbon dioxide (CO₂) and then determine if the molecule is polar or
nonpolar.
+
A) Nonpolar
B) Polar
The Correct Answer and Explanation is :
Lewis Structure of Carbon Dioxide (CO₂)
To draw the Lewis structure of carbon dioxide (CO₂), follow these steps:
- Count the Total Valence Electrons:
- Carbon (C) has 4 valence electrons.
- Each Oxygen (O) has 6 valence electrons, and there are two O atoms.
- Total: (4 + (6 \times 2) = 16) valence electrons.
- Determine the Central Atom:
- Carbon is less electronegative than oxygen, so it will be the central atom.
- Place Oxygen Atoms Around the Central Atom:
- Arrange the two oxygen atoms on either side of the carbon atom.
- Distribute Electrons:
- Place two electrons (one pair) between the carbon and each oxygen to form bonds.
- After forming two single bonds, 12 electrons remain (16 total – 4 used in bonds = 12).
- Complete the Octets of the Oxygen Atoms:
- Each oxygen needs 8 electrons to complete its octet. Place six electrons (three pairs) around each oxygen.
- Form Double Bonds:
- Each oxygen has 8 electrons now, but carbon only has 4. To satisfy the octet rule for carbon, convert one lone pair from each oxygen into a double bond.
- The final Lewis structure shows carbon double-bonded to each oxygen:
[
O=C=O
]
Polarity of CO₂
Answer: A) Nonpolar
Carbon dioxide (CO₂) is a linear molecule with a symmetrical arrangement of its bonds. The molecular geometry can be described as linear because the angle between the oxygen-carbon-oxygen (O-C-O) atoms is 180 degrees.
Despite the presence of polar covalent bonds (since oxygen is more electronegative than carbon), the symmetry of the CO₂ molecule causes the dipoles to cancel each other out. Each C=O bond has a dipole moment pointing towards the oxygen atoms, but because the molecule is linear, these dipoles are equal in magnitude and opposite in direction.
As a result, the net dipole moment of the molecule is zero, making CO₂ nonpolar. This lack of polarity has implications for its behavior in various chemical contexts. For instance, CO₂ does not interact significantly with polar solvents, like water, and is considered a nonpolar gas. This nonpolarity is also why CO₂ is relatively insoluble in water compared to more polar substances.
In conclusion, CO₂ is a nonpolar molecule due to its symmetrical linear structure, leading to the cancellation of the individual bond dipoles.