Download Polarity

Polar vs Non-Polar Molecules
• Polar bonding means that molecules have
different charges on different parts of the
molecule.
Content Objectives
• SWBAT predict whether molecules are polar or
non-polar based on the geometry of the
molecules and the differences in electronegativity
between atoms.
Polar molecules Attract Each Other
The molecules arrange themselves so
that the opposite charges attract
Polar Molecules Attract Ions Too
This is how salts dissolve in water
Non-Polar Molecules
• If all of the bonds are non-polar, then the
molecule is non-polar.
• If the bonds are polar, but the partial charges are
distributed evenly across the molecule, the
molecule is non-polar.
C-H bonds are non-polar, thus so is the molecule
Non-polar molecules usually do not mix with polar ones
Oil is non-polar, so it does
not dissolve in polar
substances like water
Polar dissolves in Polar
Molecular Polarity Distribution
• If polar bonds are distributed symmetrically, it is a
non-polar molecule.
• Thus, there is no one part of the atom that is more
positive/negative than the rest.
Uneven Molecular Polarity
• CO2 and H2O both have ends that are uneven
polarity. But, geometry matters.
• CO2 has an even distribution of charge, while
water is bent leaving a – and two + ends.
Is Ethanol polar or non-polar
• C2H5OH
-
+
Polar vs. Non-polar
• C2F4
• HCl
• NH3
• BF3
• CH3Cl
+
+
-+
+
+
+
+
+
-
Is Alanine Polar?
• A critical amino acid in your body
Dimethyl Sulfide
Nitrous Acid
Glucose?
Content Objectives
• SWBAT predict whether molecules are polar or
non-polar based on the geometry of the
molecules and the differences in electronegativity
between atoms.