Question

i cannot understand what a dipole is. can someone help me? and PLEASE use simple and layman terms

Answer 1

A dipole is the separation between +ve and -ve charges or you can say that the electric field of both the charges are intracting with each other.for example two equal and opposite charges separated by some distance more than thier nuclear distances

Answer 2

and ve is...?

Answer 3

+ve means positive and -ve means negative

Answer 4

Formally, an electrical dipole is separation of + and - charge. But when we are talking about molecules, we think of a dipole as the result of an uneven distribution of electrons throughout the molecule, since electrons are the charge that is moving around and may wind up, on average, spending more time clustered around certain parts of the atom. Imagine electrons as bees zooming around a yard - they won't spend an equal amount of time everywhere, but they will go to the plants and flowers they find most attractive. Not all atoms attract electrons to the same degree, but those that are most attractive to electrons are considered most electronegative, making the area around these atoms more likely to contain a higher density of electrons.

When we expand our viewpoint to include a larger universe than a single molecule, we realize that by creating regions of higher electron density (or uneven charge distribution) throughout a molecule, those areas will then interact very differently with nearby charged particles. Regions with more electrons will find themselves attracted to nearby positive charges, than regions with less electrons.

The dipole moment is how we describe that distribution of electrons (or charge) in a molecule- how big are the charges, and how far apart are they?

So how can you picture a dipole?
Did you ever watch the cartoon "catdog" because a dipole is kind of like that - it is "bipolar", and if one end of that molecule thinks it is positive, and wants to find electrons to hang out with, then the other end of the molecule thinks it is negative, and wants to hang out with positive charges.

Answer 5

what about dipole-dipole force...what is it?

Answer 6

btw...in your last paragraph @lizcody1 you made it seem like a dipole is not just one but sets because you said the sides will look for something to hang out with...then it cant be alone

Answer 7

dipose dipole forces are the forces that arise in between 2 different molecules (intermolecular forces) that arise as a result of the unequal distribution of charge.

Answer 8

a dipole can arise on a single molecule in isolation due to the unequal electronegativity (attractive force) of the component atoms, but molecules don't usually occur all by themselves do they? Since they usually have other molecules around, which also exhibit dipoles, this gives rise to attractive forces between the molecules.

Answer 9

when does it happen and when does it *not* happen? the dipole-dipole i mean

Answer 10

let's say you have a noble gas - all the elements are individual atoms that do not interact to form molecules, so no dipole will form, thus no dipole-dipole forces. Also molecules made up of 2 identical atoms (like O2) will have equal electronegativity, so electrons will on average spend equal amounts of time around both atoms, so no dipole forms, so these molecules will not participate in dipole-dipole interactions.

Answer 11

so noble gases and diatomic molecules do not form dipole-dipole force?

Answer 12

noble gases are subject only to london (dispersion) forces - I may need to double check about diatomics, since i'm imagining they might have unpaired e-.

Answer 13

but do noble gases have dipoles? or they dont either?

Answer 14

Noble gases do not have dipoles. However, I was wrong about diatomics - they can have dipoles due to the way electrons will fly around the molecule. Even homonuclear diatomics (where both atoms are the same) can have dipole moments. See here http://www.pi5.uni-stuttgart.de/en/research/news_from_the_lab/show_file.php/news_from_the_lab/145/

Answer 15

But in basic intro chemistry - you could probably get away with saying homonuclear diatomics don't have dipoles, or cite this link and get extra credit points
:)

Answer 16

i dont even know what homonuclear is =))

Answer 17

diatomic just means 2 atoms so CO is diatomic. Homonuclear diatomic means 2 atoms of the same kind like O2 or N2

Answer 18

so.....dipole is a behavior of a molecule? it's an event?

Answer 19

it sounds more exciting than it is..,. And yes, Dipole is behavior of electrons in a molecule that arises from the properties of its component atoms, but then this dipole "event" will cause the molecule(s) to behave in certain ways.

Answer 20

i see..i think im beginning to visualize it now...what about ion-dipole force what is it? how do i know if something has it?

Answer 21

if a molecule has a dipole (unequal distribution of electrons) than parts of that molecule will act more - or + which means it will act more like an ion and so molecules that are ions and molecules that have no net + or - charge, but do have dipoles will want to interact with eachother (since the + and - will atract)

Answer 22

good luck, I will check back later tonite if you have more questions!

Answer 23

thanks for the explanation :D

Answer 24

@lizcody1 can you give me an example or two of a molecule that has dipole-dipole force? i need to see the pattern it follows :)

Answer 25

Sure -water is a classic example. It has 2 Hydrogen atoms which are not very electronegative and 1 oxygen which is much more electronegative. When you draw a water molecule, you can also draw the distribution of charge, and then draw a vector (an arrow) that points from the more positive to the more negative area - in water, there are 2 arrows pointing from each hydrogen to the oxygen, but the net (total) dipole is the sum of these vectors...