[lokifenrir96]

Hi, can someone explain why a polar molecule must fulfill the condition of having asymmetry about the central atom, and not just the condition of different atoms having different electronegativities? I mean, IF a water molecule was linear, wouldn't the O atom in the centre still have a negative dipole, and the two H atoms still have positive dipoles, so shouldn't it still be able to act as a polar solvent and do stuff like solvate ionic compounds? Thanks!

[sjb]

Hi, can someone explain why a polar molecule must fulfill the condition of having asymmetry about the central atom, and not just the condition of different atoms having different electronegativities? I mean, IF a water molecule was linear, wouldn't the O atom in the centre still have a negative dipole, and the two H atoms still have positive dipoles, so shouldn't it still be able to act as a polar solvent and do stuff like solvate ionic compounds? Thanks!

If water was linear, you could consider it to be similar to carbon dioxide. Do you think that is polar?

[lokifenrir96]

Exactly, no. But that doesn't answer the question

[sjb]

Consider working out the dipole moment for the entire molecule, rather than individual bonds.

[curiouscat]

Exactly, no. But that doesn't answer the question

Think vectors!

Two elephantine pulls in exactly opposite directions will yet yield a zero net force. Not so if they are angled though. 

 

[AWK]

IF a water molecule was linear

Wrong assumption, water molecule is bent.

[lokifenrir96]

Haha okay I guess the vector explanation works. Though I'd welcome any better explanations? I was just confused because to me, it seems that there is still a negative dipole in the middle, and positive dipoles at the side. But okay if considering the entire molecule.

I know the assumption was wrong. It was just hypothetical.