## Water molecule and dipole moments

Matthew Leung 1B
Posts: 20
Joined: Fri Jun 23, 2017 10:39 am

### Water molecule and dipole moments

Cam someone please explain why H2O is bent and how is this related to the dipole moments (i.e., why is it polar)?

Chem_Mod
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### Re: Water molecule and dipole moments

Water is bent because the oxygen has 2 single bonds and 2 lone pairs, which gives a structure of bent. This structure is because the 2 lone pairs have a negative charge causing them to repel each other and push what would normally be a linear molecule, from the 2 single bonds, to have a smaller angle. This means that there is an angle of $104.5^{\circ}$ between the 3 atoms, instead of the typical $108^{\circ}$ of a linear molecule. This means that when you look at the electronegativity (EN) difference between oxygen and the hydrogen, to determine dipoles and if a molecule is polar or non-polar, you will want to draw an arrow from the less EN atom to the more EN atom. So draw an arrow from the H to the O. If the molecule was linear then the two arrows would cancel out by pointing at each other, but since there is an angle the two arrows don't cancel and there is a net negative charge on the oxygen. This makes the water polar.

Matthew Leung 1B
Posts: 20
Joined: Fri Jun 23, 2017 10:39 am

### Re: Water molecule and dipole moments

Thanks, so detailed.