2012 Molecule Polarity

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2012 Molecule Polarity

  1. 1. IB Chemistry Power Points Topic 4 Bondingwww.pedagogics.ca LESSON Determining Molecule Polarity
  2. 2. DEMONSTRATION - POLAR MOLECULESEvidence place a liquid in a burette allow it to run out place a charged rod alongside the stream of liquid polar molecules are attracted by electrostatic attraction non-polar molecules will be unaffected NET DIPOLE - POLAR NON-POLAR
  3. 3. Determining Molecular PolarityWe must know if individual covalent bonds are polar and the shape of the moleculeExample 1 : nitrogen gas molecules containing only non-polar bonds ARE NOT POLAR
  4. 4. Determining Molecular PolarityWe must know if individual covalent bonds are polar and the shape of the moleculeExample 2 : hydrofluoric acid HF bond dipole
  5. 5. Determining Molecular PolarityWe must know if individual covalent bonds are polar and the shape of the moleculeExample 2 : hydrofluoric acid HF molecule dipole molecule is POLAR
  6. 6. Example 3 Methane C-H bonds slightly polar but molecule is symmetrical bond dipoles cancel out C molecule is NON-POLAR
  7. 7. Example 4 Ammonia N-H bonds polar molecule is asymmetrical lone pair (negative) hydrogen atoms (positive) molecule is POLAR
  8. 8. Example 5 water
  9. 9. POLAR MOLECULES - SUMMARYConcept s molecules containing non-polar bonds are non-polar symmetrical polar bonds: the molecule isn’t polar asymmetrical polar bonds: the molecule will be polar HYDROGEN CHLORIDE TETRACHLOROMETHANE WATERNET DIPOLE - POLAR NON-POLAR NET DIPOLE - POLAR To determine molecular polarity, we must know molecular shape and bond polarity.

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