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Published byAugustine Miles Modified over 9 years ago
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CHM 101 Predicting and Understanding the Behavior of Molecules
Sinex Molecular Polarity Predicting and Understanding the Behavior of Molecules PGCC CHM 101 Sinex
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Molecular Polarity - How?
Lewis dot structure geometry bond polarity (DEN) and lone pairs how is the charge distribution – symmetrical or asymmetrical? Electrostatic potential map using Chime N2 HCl Spartan 02 Chime activity - Click here
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Molecular Polarity - Why?
Interactions with other molecules and physical properties such as boiling point, surface tension, and solubility Intramolecular interactions – within molecule such as proteins Reaction mechanisms – where attacked
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An experimental measurement
The dipole moment, m, is given by = Qd where Q is the charge and d is the separation distance of the charge The unit is the debye, D.
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Measurement: Dipole Moment
No voltage applied on metal plates d- d+
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Measurement: Dipole Moment
- + Voltage applied on metal plates d- d+
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Dipole Moments DEN m (D) Hydrogen Halide Bond length (pm) HF 1.9 92
1.82 HCl 0.8 127 1.08 HBr 0.6 141 0.82 HI 0.3 161 0.44 Increasing polarity
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Dichloromethane, CH2Cl2 mcalc = 1.50 D Spartan 02
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Ammonia, NH3 mcalc = 1.85 D Spartan 02
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A square planar complex - Pt(NH3)2Cl2
Polar or Non-polar Cl-Pt-N = 80o Cl-Pt-Cl = 101.4o polar Non-polar Spartan 02
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Polar or non-polar molecules?
CCl2F2 HCN SCl4F2 ICl3 BCl3 BrCl
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