Can you please answer this question: Both water and carbon dioxide are triatomic molecules. Explain why one of these molecules is polar and the other is nonpolar?

Question

Carbon dioxide is linear :C::O::C: and therefore has no net electrical dipole.

Water is a bent molecule , so the O side acts a negative, making the molecule polar.
http://library.tedankara.k12.tr/chemistry/vol2/hydrogen%20bonding/z20.jpg

CO2 is a linear molecule like this
O=C=O. The difference in electronegativity (EN) of the O and C makes the left O=C bond polar and the right C=O bond polar but the linear symmetry cancels each other and the molecule as a whole is not polar. That isn't so with the water molecule. It is not linear. It's tough to draw the structure on these boards but it looks something like this.
H
|
O - H.
Now the difference of one EN for O and H makes both bonds polar (as in the case of CO2) but the water molecule is not linear, hence it isn't symmetrical, and the two polar bonds don't cancel each other. That is to say that there is a net dipole moment.

why is water a bent molecule, but carbon dioxide is linear?

Answer 1

Water is bent because of the two lone pairs of electrons on the oxygen atom. These lone pairs of electrons cause the molecule to be bent, rather than linear. Carbon dioxide is linear because the two oxygen atoms are bonded to the carbon atom in a linear fashion, and the lone pairs of electrons on the oxygen atoms do not cause the molecule to be bent.