Could someone explain dipole-dipole forces for me?
It would be great to be able to draw on these boards but such is not the case. Probably better for me to give you a site where the pictures can tell you. Post back if they pictures are not clear. Pick one of the following and click on it. The first one looks good to me.
http://www.google.com/search?q=dipole+dipole+pictures&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a
Dipole means two ends having opposite charge.A dipole is usually formed in a molecule in which one of the atoms is highly electronegative.For example HCl
Here Cl is highly electronegative which attracts the electrons present between H and Cl towards itself.As a result a negative charge develops on Cl and positive charge is formed towards H.
Now the when these dipoles interact,the positive pole of one dipole is attracted towards negative pole of other dipole.This attraction is called dipole-dipole force.
NOTE-Dotted line you see in picture given in above link shows dipole-dipole force.
Certainly! Dipole-dipole forces are a type of intermolecular force that exists between two polar molecules. To understand dipole-dipole forces, it's important to first understand polarity.
Polarity refers to the separation of electric charge in a molecule, resulting in a positive pole and a negative pole. This occurs when the electronegativity (the ability to attract electrons) of two atoms within a molecule differ significantly. The atom with higher electronegativity will pull the shared electrons closer to itself, creating a partial negative charge, while the other atom will have a partial positive charge.
Now, when two polar molecules come close to each other, their positive and negative ends align and attract each other. This electrostatic attraction is called a dipole-dipole force.
One example of a compound with dipole-dipole forces is hydrogen chloride (HCl). In HCl, the electronegative chlorine atom attracts the electron pair in the covalent bond more strongly, resulting in a partially negative chlorine atom and a partially positive hydrogen atom. When two HCl molecules come close, the positive end of one molecule attracts the negative end of the other molecule, creating a dipole-dipole attraction.
To determine whether a molecule has dipole-dipole forces, you need to know the molecular shape and the electronegativity difference between atoms. You can find this information by looking up the electronegativity values of each atom in the molecule and calculating the polarity based on their positions and charges.
In summary, dipole-dipole forces are intermolecular forces that occur between polar molecules due to the attraction between the positive and negative ends of the molecules. These forces play a significant role in determining the physical properties of compounds such as boiling and melting points.