Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: chstudent24 on July 07, 2009, 11:20:04 AM
-
I'm at a loss of how to even begin this question.
What kind of intermolecular attractive force is shown in each of the following cases? (They show little circle diagram shapes with 5 dots connection each)
a. HF....HF
b. FF.....FF
c. Na+..OH2
d. SO2.....SO2
I'm really stumped on how to even begin.
-
It may be helpful to first list the possible intermolecular forces that you know, organize them from strongest to weakest, then go down the list and see which force one applies to which case.
-
Ok so here is my updated thought process please let me know if I'm wrong in my thinking.
a. HF....HF
Ok so this is a Hydrogen bond since they exist when H is covalently bonded to N, O, or F which we have here. And since F has a very high EN this makes it very polar which hydrogen bonds are
b. FF.....FF
This is a London Dispersion since the F2 and F2 cancel out the EN of each other creating a non polar molecule which defines a London Dispersion force
c. Na+..OH2
This is an ionic bond because it first invovles a bond between a metal and non metal and is formed by 2 oppositley charged ions.
d. SO2.....SO2
Dipole-Dipole because this force requires 2 polar molecules. The polarity can be easily determined from the bent shape of these molecules
-
Great! All are correctly explained except for c. As you correctly state, an ionic bond is a bond between two oppositely charged substances. Clearly Na+ fits this description, but H2O is not charged. This is actually an example of an ion-dipole interaction (because Na+ is an ion and H2O is polar and has a permanent dipole), and interaction that is generally weaker than an ionic bond.