# Why is a compound as common as water considered a "weird" chemical substance?

Dec 1, 2016

#### Explanation:

Water contains hydrogen bonds between the molecules which means that it will remain as a liquid at much higher temperatures than you would expect. This also enables the molecules to 'stick' together and gives water surface tension. The way that water forms into a solid also means that the solid of water (ice) is much less dense than the liquid, allowing it to float.

Dec 1, 2016

Consider its normal boiling point, which you know........

#### Explanation:

Compare the normal boiling point of water to that of $C {H}_{4}$, $S i {H}_{4}$, $H F$, ${H}_{2} S$, or $P {H}_{3}$. The boiling point of water is disproportionately high. This is also unusual in that water has a very small molecular mass (and thus little possibility of $\text{van der Waals interactions}$.

And now compare the density of liquid water to the density of solid water. Icebergs float in the ocean! I grant that things are more buoyant in salty water, however, ice cubes also float in ice-water or in your gin and tonic. This is highly unusual, in that, save water, there are very few substances that as liquids are DENSER than their solid phases.

I would consult a textbook on the unusual properties of water. These properties are largely the result of the propensity of the water to $\text{hydrogen-bond}$ intermolecularly.