# Why are H2O asymmetric while CO2 is not? [duplicate]

What is the reason for water molecules $\ce{H_2O}$ being asymmetric while other molecules like $\ce{CO_2}$ being completely symmetric? See the pictures below:

In both case there is an electronegative difference between the atoms in the molecule. I have read that the angle in the water molecule is always a specific value. Is this a special thing for water or is there a common mechanism I should know?

• That's because of the lone pairs of oxygen. We have the notorious VSEPR, the mathematical hybridization, and the ultimate molecular orbital theory to explain this. Have you studied any of them? Jun 8 '15 at 18:13
• Related: Why is H₂O a dipole?
– user7951
Jun 8 '15 at 18:39