Almost every substance known to modern science expands
when it melts, and continues to expand as it is heated. That is,
its volume increases.
A shocking exception to this rule is the substance Dihydrogen Monoxide.
This substance contracts when it changes from the solid phase
to the liquid phase, and its volume continues to decrease as the
liquid is heated for 4 more degrees Celsius above its freezing/melting
point.
The result is that this amazing substance is the only one known whose
solid form floats in its liquid form, and whose liquid form near freezing
temperature rises to the top of a pool of slightly warmer liquid.
The chemical formula for Dihydrogen Monoxide is: H₂O .
The pure form is colorless, odorless, tasteless, and non-toxic.
In addition to its occurrence in nature, it is also found in faucets,
sinks, and toilets in most homes.