1 / 15

Polar and Non-polar Molecules

Polar and Non-polar Molecules. Review: Polar Bonds. When a bond is polar, one atom in the molecule is attracting the shared electron more than the other atom (unequal sharing of electrons) Polar bonds does NOT necessarily equal a polar molecule!!!!!. Polar vs. Non-polar Molecules:.

lyre
Download Presentation

Polar and Non-polar Molecules

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Polar and Non-polar Molecules

  2. Review: Polar Bonds • When a bond is polar, one atom in the molecule is attracting the shared electron more than the other atom (unequal sharing of electrons) • Polar bonds does NOT necessarily equal a polar molecule!!!!!

  3. Polar vs. Non-polar Molecules: • Molecules can either be polar or non-polar based on the combining effect of all the polar bonds within that molecule.

  4. Non-polar Molecules: • When looking at the shape of a molecule, if one polar bond cancels the polar effect of the other polar bond, in the opposite direction, the molecule will be non-polar. • Ex: CO2 is a non-polar molecule d – d – d + d +

  5. Example: CF4 In CF4 the Fs are symmetrically arranged around the carbon.

  6. d – d – d + d – d – • The Fs all pull on the valence electrons in • opposite directions • Each C – F bond is polar • But they all effectively cancelling out • the polarity of the bonds

  7. CF4 has four polar bonds but it is a non-polar molecule!

  8. Polar Molecules: • If there are polar bonds in a molecule, but the forces are not in opposite directions, the polar charges will not cancel, and the molecule will be polar. • This means that overall the molecule will have positive and negative ends.

  9. Polar molecules (2): • When the atoms attached to the central atom are not all the same type of atom, the force of the pulls on the electrons are more difficult to be equaled/cancelled out. The molecule will be polar.

  10. Ex: H2O • The two Hs of water are not symmetrically positioned around the oxygen.

  11. Ex: H2O d – d + d + • The O-H polarities do not cancel, • and the molecule carries a partial charge. • This is a polar molecule!!

  12. Molecules with 3 Atoms Even though the C-O bond is polar, the bonds cancel each other out because the molecule is linear the dipole moments are equal and in opposite directions. Therefore CO2 is non-polar. CO2 The dipole moment between H-C points in the direction of C. The dipole moment points between C-N points in the direction of the N. Therefore the dipole vectors are additive and HCN is polar HCN SO2 SO2 is a polar molecule because the S-O dipole Moments don’t cancel each other out due to the angle

  13. Molecules with 4 Atoms CCl4 is non-polar CHCl3 is polar

  14. How to determine if molecule is polar or non-polar: • Draw the correct Lewis diagram. • Determine the shape of the molecule. • Determine and label each individual bond polarity (with arrow and ). • Determine if the individual bond polarities cancel each other out or not. d s

  15. Practise Problems: • Predict the shape, determine the bond polarity and the overall polarity of each molecule: 1. NH3 2. CCl4 3. HCCl3 4. H2S 5. CH3F 6. CH2O 7. AsI3 8. H2O2 • Pg 196 #9, 10

More Related