1 / 21

Molecular Geometry

Molecular Geometry. VSEPR - Valence Shell Electron Pair Repulsion Theory. In small molecules, electrons and bonds are arranged as far apart as possible. Molecular Geometry. This allows for atoms to have 3-D shapes different from their shapes in 2-D (paper). Molecular Geometry.

shanae
Télécharger la présentation

Molecular Geometry

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. Molecular Geometry • VSEPR - Valence Shell Electron Pair Repulsion Theory. • In small molecules, electrons and bonds are arranged as far apart as possible.

  2. Molecular Geometry • This allows for atoms to have 3-D shapes different from their shapes in 2-D (paper).

  3. Molecular Geometry • Linear – the bonds form a straight line. • Example CO2 • Bond Angle 180⁰ [http://cwx.prenhall.com/bookbind/pubbooks/hillchem3/medialib/media_portfolio/text_images/CH10/FG10_02-02d.JPG]

  4. [http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter07/Text_Images/FG07_05-01UN.JPG][http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter07/Text_Images/FG07_05-01UN.JPG]

  5. Molecular Geometry • Trigonal Planar– The central atom has only 3 bonds. • Example: CH2O (Formaldehyde) • Bond angle 120⁰ [http://wps.prenhall.com/wps/media/objects/476/488316/Instructor_Resources/Chapter_10/FG10_00-66c.JPG]

  6. [http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter07/Text_Images/FG07_05-01UN.JPG][http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter07/Text_Images/FG07_05-01UN.JPG]

  7. Molecular Geometry • Tetrahedral –The central atom has only 4 bonds • Example: CH4 (methane) • Bond Angle 109.5⁰ [http://wps.prenhall.com/wps/media/objects/476/488316/Instructor_Resources/Chapter_10/FG10_00-69d.JPG]

  8. [http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter07/Text_Images/FG07_05-01UN.JPG][http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter07/Text_Images/FG07_05-01UN.JPG]

  9. Molecular Geometry • Trigonal Pyramidal –Central atom has 3 bonds and one lone pair of electrons that “pushes” the bonds away. • Example: NH3 (ammonia)

  10. [http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter07/Text_Images/FG07_05-01UN.JPG][http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter07/Text_Images/FG07_05-01UN.JPG]

  11. Molecular Geometry • Bent – Here there are two bonds and two pairs of electrons on the central atom. • Example: H2O (water) [http://www.elmhurst.edu/~chm/vchembook/images/206water.gif]

  12. [http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter07/Text_Images/FG07_05-01UN.JPG][http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter07/Text_Images/FG07_05-01UN.JPG]

  13. [http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter07/Text_Images/FG07_05-01UN.JPG][http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter07/Text_Images/FG07_05-01UN.JPG]

  14. Polarity • When 2 atoms in a bond have different electronegativity values, electrons can be “pulled” more toward one side of the bond. • A bond where this occurs is called a dipole.

  15. [http://www.cybered.net/library/Teaching_Resources/Chemistry/Bonding_II/Image_Gallery/Bonding2--PolarBond.jpg][http://www.cybered.net/library/Teaching_Resources/Chemistry/Bonding_II/Image_Gallery/Bonding2--PolarBond.jpg]

  16. [http://cwx.prenhall.com/bookbind/pubbooks/hillchem3/medialib/media_portfolio/text_images/CH09/FG09_11.JPG][http://cwx.prenhall.com/bookbind/pubbooks/hillchem3/medialib/media_portfolio/text_images/CH09/FG09_11.JPG]

  17. Polarity • Showing Polarity • “Minus” sign above the high electronegative atom. • “Plus” sign over the other atom. • Draw arrow from plus to minus. [http://cwx.prenhall.com/bookbind/pubbooks/hillchem3/medialib/media_portfolio/text_images/CH09/FG09_11-02.JPG]

  18. Compound Polarity • Draw a correct 2-D compound with arrows along each bond. • Example: CH4 H H C H H

  19. Compound Polarity • Then, check to see if any of the arrows cancel out. • To do this think “tug of war” H H C H H

  20. Compound Polarity • If all arrows cancel out, the molecule is non-polar or covalent. • If the arrows do not cancel out, the molecule is polar or polar-covalent.

  21. Compound Polarity • Remember: 3D shape determines 2D drawing. • Example: H2O H O H H O H

More Related