Examining Molecules Polar or Nonpolar Bonds? Shape of the Molecule? Yes Lewis Structure: Water: H2O Structural formula: H-O-H Acetone: CH3COCH3 Structural formula: CH3-CO-CH3 Hexane: C6H14 Structural formula: CH3(CH2)4CH3 Ethanol: C2H5OH Structural formula: CH3CH2OH
The Correct Answer and Explanation is:
To determine whether the bonds and molecules are polar or nonpolar, we need to analyze both the polarity of the bonds and the overall shape of the molecule.
- Water (H2O)
- Bond Type: Water has polar covalent bonds. Oxygen is more electronegative than hydrogen, so the electron density is pulled toward the oxygen atom, creating a dipole.
- Shape: The water molecule has a bent shape (due to the lone pairs on oxygen), which results in an overall dipole moment.
- Polarity: Since the molecule has an uneven distribution of charge due to its bent shape and the polarity of the bonds, water is a polar molecule.
- Acetone (CH3COCH3)
- Bond Type: The C–O bond in acetone is polar because oxygen is more electronegative than carbon. The C–C bonds are nonpolar.
- Shape: Acetone has a trigonal planar shape around the carbonyl group (C=O), and it is symmetrical about this bond.
- Polarity: Acetone is a polar molecule because of the polar C–O bond and the asymmetrical distribution of the electron density.
- Hexane (C6H14)
- Bond Type: All C–C and C–H bonds in hexane are nonpolar because carbon and hydrogen have similar electronegativities.
- Shape: Hexane is a linear molecule with no significant dipoles.
- Polarity: Since hexane has only nonpolar bonds and a symmetrical shape, hexane is a nonpolar molecule.
- Ethanol (C2H5OH)
- Bond Type: Ethanol has both polar covalent bonds (C–O, O–H) and nonpolar C–C and C–H bonds.
- Shape: The ethanol molecule is bent due to the O–H bond, resulting in a dipole moment.
- Polarity: The polar bonds in ethanol and its bent shape lead to a polar molecule.
Summary:
- Water is polar.
- Acetone is polar.
- Hexane is nonpolar.
- Ethanol is polar.
The polarity of each molecule is mainly determined by the nature of the bonds (polar vs nonpolar) and the molecular shape. A symmetrical shape generally results in a nonpolar molecule, while an asymmetrical shape often leads to a polar molecule.
