1 / 11

Molecular Geometry

Molecular Geometry. VSEPR Theory. Molecular geometry. Area of chemistry that deals with the shape of molecules . Shape determines many properties about a molecule: Reactivity Smell Taste. Molecular shape.

hanne
Download Presentation

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 Theory

  2. Molecular geometry • Area of chemistry that deals with the shape of molecules. • Shape determines many properties about a molecule: • Reactivity • Smell • Taste

  3. Molecular shape • Lewis Structures do not reveal anything about the 3-D arrangement of atoms in a molecules. • Could you have predicted the 3-D shape of CCl4 from the Lewis structure on the left?

  4. VSEPR Theory • Valence Shell Electron Pair Repulsion Theory • States that molecules will take on shape that is lowest in energy. • A low energy shape is one that minimizes the valence shell electron pair repulsion (VSEPR) between adjacent atoms. • Atoms in a molecule try to spread out from one another as much as possible to reduce the “like charge repulsion” between their outer electrons.

  5. Vsepr Example • Methane, CH4 • You might think this is the farthest that the hydrogens can get away from each other. • But if you think in 3 dimensions, this shape actually causes less repulsion between the bonding pairs of electrons.

  6. Steps for determining molecular geometry • 1. Draw proper Lewis structure. • 2. Count the # of bonded atoms and # of lone pairs around the central atom. • 3. Use CHART to determine name of shape. • 4. Redraw shape with proper geometry.

  7. 0 Geometry Chart

  8. Big picture on molecular geometry • These bonds (shared electrons) and lone pairs of electrons are all negatively charged so they want to spread out from each other as much as possible within a molecule. • This minimizes “like charge repulsion” between electrons and represents for the molecule.

  9. Difference between bonded electrons & Lone Pairs • Lone pairs take up more space than bonding pairs and thus push atoms farther away from each other. • This decreases the predicted bond angles.

  10. Example – nH3 • 1. Draw proper Lewis Structure. • 2. Count the # of bonded atoms and # of lone pairs around the central atom. • 3 Bonded Atoms • 1 Lone Pairs • 3. Use CHART to determine name of shape. • Trigonal Pyramidal • 4. Redraw shape with proper geometry.

  11. Example – CH3F • 1. Draw proper Lewis Structure. • 2. Count the # of bonded atoms and # of lone pairs around the central atom. • 4 Bonded Atoms • 0 Lone Pairs • 3. Use CHART to determine name of shape. • Tetrahedral • 4. Redraw shape with proper geometry.

More Related