what is the difference between bond polarity and molecular polarity?
Since HCl molecule is defined as a molecule that consist of a hydrogen atom bonded to a chlorine atom, and the bond is polar, this also implies that the molecule is polar.UrbanXrisis said:so does HCl have a polar or nonpolar "molecular bond"? I wrote down polar but I think it has to be nonpolar acording to what you said
For instance, for a bond to be polar, there must be an unequal distribution of electrons amongst the bonded pair, due to the unequal electronegativity. Usually the less electronegative element is in the center of the molecule. However, if the molecule is symmetrical, by vector-adding, the attraction of the electrons is "cancelled" out since a substance on the opposite end provides an equal attractive force , due to the symmetry, upon the electrons.UrbanXrisis said:how is the molecule polar if the structure is symmetrical?
does this mean every polar bond must have be a polar molecule?
because that's all the molecule is made of, just the linear polar bond of hydrogen and chlorine. There's nothing there to counter-act the electronegativity difference, unlike in a symmetrical molecule, and thus the molecule is polar. And by the way, being a linear molecule does not mean it will always be symmetrical, for instance HCl molecule. In general, if the opposite sides do not resemble each other, then the molecule should not be symmetrical (this is going on a limb here, but it works in most cases)...UrbanXrisis said:all I know is that symmetrical molecules are nonpolar molecules. That means linear and tetrahedral bonds are considered nonpolar molecules. However, if the EN is between .5-1.7 then it has a polar BOND. So, back to HCl
H-Cl has a linear bond, that means it is a nonpolar molecule.
However, HCl is a EN difference over .5 which means it is a polar bond.
Why is HCl a polar molecule as you said?
You are correct.UrbanXrisis said:what about H2CO? it's a polar molecule and also has a polar bond right?
Did your teacher explain to you about the different molecular geometries? I'll help you out. Well there's 0 nonbonding pairs and 3 bonding pairs... There's your hint...UrbanXrisis said:would this molecular structure be called bent or pyramidal? or is it called something else?
great job... way to help someone learn...t!m said:The structure of [tex]H_2CO[/tex] would be trigonal planar, with 120 degree bond angles.
Yes. C=N bond is nonpolar, but once you bond it with hydrogen ion, H+ and CN- forms together and becomes polar. Due to the positive and negative attraction in between these two ions, Hydrogen ion(the positive end of the polar vector) reaches, or becomes pulled towards the CN- ion(also known as the negative end of the polar vector which attracts the positive end).t!m said:Ack, this sort of thing really depends on teacher. No bond is truly nonpolar except for bonds between identical atoms, i.e. C-C bonds. If you're following the rules for END, then yes, I suppose, C=N is a nonpolar bond.
To be specific of what T!M is implying, linear bonds with the same bond type/strength would be always nonpolar. The example given by T!M, HCN, is a polar molecule indeed because there is a single bond on the left, and a triple bond on the right. Thus, cannot balance these two different bond types. On top of that, according to the vector analysis, both of the vector lines are facing right, and cannot cancel each other out, making the HCN polar. O=C=O would be nonpolar(linear) because of the equalivalent attrativeness/polarity between the O=C and C=O.t!m said:Linear bonds are not always nonpolar. I think you're overgeneralizing the concept of symmetry. HCN is actually a polar molecule. Also, both bonds are polar as well, which is actually the reason for the molecule's polarity. Try http://onsager.bd.psu/~jircitano/polar.html [Broken] site.