1 / 21

Molecular Geometry

Molecular Geometry. VSEPR model. V alence S hell E lectron P air R epulsion Shape of molecule is determined by the repulsion of electron pairs around the central atom . The repulsion must be minimum , i.e. Electron pairs are farthest from each other ( potential energy minimum ).

inoke
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 model • Valence Shell Electron Pair Repulsion • Shape of molecule is determined by the repulsion of electron pairs around the central atom. • The repulsion must be minimum, i.e. Electron pairs are farthest from each other (potential energy minimum).

  2. Rules • Draw the right Lewis Structure (formal charge!). • Determine the number of electron pairs around the central atom. • Multiple bonds are treated as if they were one electron pair because these electron pairs can not be separated from each other • 2, 3, 4, 5 or 6 EP.

  3. CA Two EP around Central Atom (AX2) BeCl2 Cl Be Cl 2 EP Cl Be Cl Shape:linear Bond angleCl-Be-Cl = 180º X-A-X

  4. F F B F CA Three EP around Central Atom (AX3) 3 EP AX3 BF3 F B F F Shape:planar triangular Bond angleF-B-F = 120º X-A-X

  5. O S O CA Three EP around Central Atom (AX3) 3 EP AX2E SO2 S O O < Shape:V-shaped (bent) Bond angleO-S-O = 120º X-A-X Lone EP occupies a larger space than bonding EP.

  6. H C H H H CA Four EP around Central Atom (AX4) 4 EP AX4 CH4 H C H H H Shape:tetrahedral Bond angleH-C-H = 109.5º X-A-X

  7. N H H H CA N H H H Four EP around Central Atom (AX4) AX3E 4 EP NH3 < Shape:trigonal pyramidal Bond angleH-N-H = 109.5º X-A-X Lone EP occupies a larger space than bonding EP.

  8. O H H CA O H H Four EP around Central Atom (AX4) AX2E2 4 EP H2O < Shape:V-shaped Bond angleH-O-H = 109.5º X-A-X Lone EP occupies a larger space than bonding EP.

  9. Cl Cl P Cl Cl Cl CA Five EP around Central Atom (AX5) AX5 5 EP PCl5 Cl Cl Cl P Cl Cl Shape:trigonal bipyramidal Bond angleCl-P-Cl = 120º, 90º X-A-X

  10. F S F F F F CA F S F F Five EP around Central Atom (AX5) AX4E 5 EP SF4 Lone EP occupies a larger space than bonding EP. Shape:disordered tetrahedral Bond angleCl-P-Cl = 120º, 90º X-A-X

  11. Cl I Cl Cl Cl CA Cl I Cl Five EP around Central Atom (AX5) ICl3 5 EP AX3E2 Lone EP occupies a larger space than bonding EP. Shape:T-shaped Bond angleCl-P-Cl = 120º, 90º X-A-X

  12. Cl I Cl Cl CA I Cl Five EP around Central Atom (AX5) ICl2- 5 EP AX2E3 Lone EP occupies a larger space than bonding EP. Shape:linear Bond angleCl-I-Cl = 180º X-A-X

  13. F F F S F F F CA Six EP around Central Atom (AX6) SF6 6 EP AX6 F F F S F F F Shape:octahedral Bond angleF-S-F = 90º X-A-X

  14. Cl Cl Cl I Cl Cl CA Six EP around Central Atom (AX6) ICl5 6 EP AX5E Cl Cl Cl I Cl Cl Shape:square pyramidal Bond angleCl-I-Cl = 90º X-A-X

  15. F F Xe F F CA Six EP around Central Atom (AX6) XeF4 6 EP AX4E2 F F Xe F F Shape:square planar Bond angleF-Xe-F= 90º X-A-X

  16. Polarity of molecules • Molecules polar if net dipole moment ≠ 0 • If molecule is “pure” AXn type • No lone EP • All surrounding atoms are the same element non-polar m1 m3 m2 m1 m2

  17. Usually, if there is a lone EP  polar NH3 AX3E H2O AX2E2

  18. Exceptions: Cl AX2E3 I Cl F F AX4E2 Xe F F

  19. Different ligand atoms Cl m3 BF2Cl m1+m2 > m3 m1 B F Net dipole moment ≠ 0 m2 m1+m2 F XeF2Cl2 F F Cl Cl Xe Xe Cl Cl F F nonpolar polar

More Related