10.18 Determing whether a molecule is polar.
Q: Determine whether SeO2 is polar.
S: Se & O are nonmetals w/ different electronegativities (2.4 for Se and 3.5 for O). Therefore, the Se-O bonds are polar. The geometry of SeO2 is bent.
*The polar bonds do not cancel but rather sum to give a net dipole moment. Therefore the molecule is polar.
- 1) Determine whether the molecule contains polar bonds.
- 1.1) A bond is polar if the two bonding atoms have different electronegativities. If there are no polar bonds, the molecule is nonpolar.
2) Determine whether the polar bonds add together to form a net dipole moment. Use VSEPR theory to determine the geometry of the molecule. Then visualize each bond as a rope pulling on the central atom. Is the molecule highly symmetrical? Do the pulls of the ropes cancel? If so, there is no net dipole moment & the molecule is nonpolar. If the molecule is asymmetrical & the pulls of the rope do not cancel, the molecule is polar.