What is an intramolecular force ionic covalent polar

What is an intramolecular force? ionic, covalent, polar covalent bonds What do these forces hold together? atoms

Intermolecular Forces Attraction forces between molecules

H Cl H H H Cl l H Cl C l CH HH H Cl Cl C l Cl H HH H HCl. Cl CCl l H Cl Cl

+ d H d Cl H H H Cl l H Cl C l CH H H Cl. Cl H HH H HCl. Cl CCl l H Cl Cl

H Cl H H H d Cl Cl. H + d Cl

+ d H d Cl

+ d H d Cl

Van der Waals forces: dipole-dipole • molecule must have at least 1 polar covalent bond • molecule must be polar • d- side of the molecule is attracted to the d+ side • can be intramolecular as well

Cl Cl

Dipole moment d - - - London force + d

Which would you expect to have the greater dipole moment? - H - - O -

van der Waals forces: London forces • molecule is non polar or polar • weak and short-lived attractive force caused by momentary dipole recall e- distribution is described as a probability at any given point in time, the distribution might be uneven, creating a temporary dipole on the molecule • increases with increasing #e- and size of molecule

-25 2. 20 x 10 lbs rubbing alcohol 2. 12 x 10 -25 lbs nail polish remover

+ d d

Which is Stronger? dipole-dipole H-bond

H–F

H–F

Example: Among H 2 O, CO 2, and H 2 S, explain why H 2 O has the highest boiling point at 100 C, followed by H 2 S at -60. 33 C, then CO 2 at-78. 44 C all 3 molecules are similar in size – boiling point difference must be attributed to intermolecular forces H 2 O is polar and has dipole-dipole interactions, and can H-bond H 2 S is polar and has dipole-dipole interactions CO 2 is nonpolar, only has London forces