Vsepr Handout - VESPR theory helper sheet PDF

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VESPR theory helper sheet...

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CHEM 3A | Bisceglia

Molecular Geometry & Molecular Polarity Valence Shell Electron Pair Repulsion (VSEPR) Theory Main Ideas: (1) Electrons repel each other, so electron pairs (i.e., bonds and lone pairs) will be as far away from each other as possible. (2) Lone pairs repel more than bonding electrons

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CHEM 3A | Bisceglia

Determining Electron and Molecular Geometries from Lewis Structures: Step 1. Determine electron pair geometry by adding the number of bonds an lone pairs around a central atom

Step 2. Determine the molecular geometry by accounting for the number of lone pairs. Placement of Lone Pairs for 2,3 and 4 electron pairs, it doesn’t matter where the lone pairs are attached.

for 5 pairs, place the lone pairs equatorially for 6 pairs, place lone pairs axially

Molecular Polarity Main idea: The three dimensional arrangement of electron density in a molecule determines its polarity. Polar Molecule Guide

Are there polar bonds present? |∆EN| ≥ 0.5?

YES Are polar bonds arranged so they cancel? (Vector sum is zero? Check direction and magnitude of polar bonds.)

NO

YES

Are there lone pairs on the central atom?

NO

Molecule is NONPOLAR

YES

Molecule is NONPOLAR

YES Are lone pairs on central atom arranged so they cancel? NO

NO Molecule is POLAR

Molecule is Weakly POLAR

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