UnitA - Molecular Polarity

When is a bond non-polar?

• If there is an equal sharing of e-

• When the electronegativities are the same

• ex) H2, O2

When is a bond polar?

• If there is an unequal sharing of e-

• When atoms in a molecule are different

• ex) H2O

Define dipole

When a bond or molecule has “two poles” - a positive side and a negative side

Can polar bonds cancel each other out?

Yes

What shape(VSPER) indicates that the molecule is non-polar?

• They will usually have a symmetrical shape

  • Tetrahedral

  • Trigonal planar

  • Linear

What shape(VSPER) indicates that the molecule is polar?

• They will always have a asymmetrical shape

  • bent

  • trigonal pyramidal

• Tip: If there are lone pairs around a central atom, it will be polar

What molecules are polar?

• Diatomic with difference atoms(ex. HCl)

• Nitrogen + other atoms(ex. NH3)

• Oxygen + other atoms(ex. H2O)

• Carbon + 2 other kinds of atoms

  (ex. C2H5OH)

What molecules are non-polar?

• All elements(ex. Cl2, N2)

• Carbon + only 1 other atoms(ex. CO2)

• All hydrocarbons(ex. CxHy, doesn’t matter what x or y is, always non-polar)