Hmm, have you wondered about how atoms are attracted to each other? The attractive force is really just electrostatic forces of attraction!
it really simplifies your understanding of chemical bonding if you know that electrostatic forces of attraction is the thing holding everything together. Just this word “electrostatic” sums up what bonding is about
this refers to the positive and negative charges that can be found in lightning strikes, makes your hair stand and build up on door knobs to give you a shock.
but we know that atoms and molecules usually are uncharged right? like good old glucose c6h12o6 and the oxygen we breathe in…
so what happens is that somehow these uncharged guys are uncharged ON THE OVERALL, but if you can imagine a COIN, with its heads or tails side…. and we all know that electrons are zipping around an atom or a compound all the time…. at one time in time, ONE SIDE of the compound has more electrons than the OTHER SIDE…. then we have a slightly positively charged pole on one side of the compound and a slightly negatively charged pole on the other side…. then we get an electric dipole that may look familiar to you
the description above is for an INDUCED dipole for uncharged guys… more information here http://www.chem.purdue.edu/gchelp/liquids/inddip2.html
for permanent dipoles, we are interested in the electronegativity of the 2 guys forming a covalent bond between them.
take note that a COVALENT BOND is compulsory or necessary because sharing of electrons occurs, and the more electronegative of the pair of atoms in a covalent bond will cause unequal sharing to occur by attracting the electrons of the pair of atoms more towards its nucleus.
more information can be found here http://chemwiki.ucdavis.edu/Physical_Chemistry/Quantum_Mechanics/Intermolecular_Forces/Dipole_moments
dipole moment is another interesting thing, although the “moment” may be confused with the idea of moments in physics. The dipole moment really looks to find out how the electric field around a compound look like.
you saw the earlier picture of the dipole right, well there is clearly an electric field there and excitingly, this electric field is what causes atoms and compounds to be attracted to each other.
So to elaborate on this concept, you know that positive and negative electric charges attract, but they can only do so THROUGH AN ELECTRIC FIELD. Well, this is simply because electric charges will create a field around it, and the field of different atoms and compounds and even electrons interact with each other to either attract or repel each other:)
the idea of dipole moment becomes important in molecules like ammonia, water where the central atom (N and O respectively) forms a number of dipoles (each covalent bond is counted as one dipole) and we need to know whether on the overall the entire compound has an electric field.
this is interesting because we know that water has a mickey mouse sort of shape so and when we look at the dipole moments of the 2 dipoles (from the 2 covalent H-O bonds) in a water molecule, on the overall, we can see that the mickey mouse ears are gonna be positively charged and the mickey mouse face is gonna be negatively charged and so we know that water is a POLAR molecule on the overall because the top part is totally belonging to the slightly positive pole and the bottom part is a slightly negative pole.