Question

How does the chemical structure of water relate to its unique properties?

Answer 1

The geometry of molecules depends on the number of atoms present in the molecule and the angles between bonds in the molecule.

For example, molecules `CO_2` and `H_2O` both have three atoms. The angle between bonds is 180° in carbon dioxide making this molecule linear. The angle between bonds in water is 104.5° making water a bent molecule.

The shapes of molecules have important implications. One is that even though both C=O bonds and O-H bonds have dipoles, carbon dioxide molecules are non-polar due to their linear shape and water molecules are polar due to their bent shape.

Here is a video which discusses VSEPR theory and molecular geometry.

video from: Noel Pauller

The polarity of water means that it will be able to form hydrogen bonds, have a high surface tension and is a very good solvent.

Check out video of a stream of water being bent - a plastic ruler is used in the demo. The stream of water bends due to the polarity of water molecules.

video from: Noel Pauller

Here is video showing how a paperclip can "float" on water - it's actually being held up by the hydrogen bonds formed between water molecules which give water its surface tension.

video from: Noel Pauller

Hope this helps!