Why does Ice float? Because God made it that way so it wouldn’t crowd out the little fishes by sinking and filling up the seas, then getting them all frozen. This was an explanation by a four year old child. Sounds like an interesting theory to me and for all I know, may be partly correct, if you believe God rather than natural cause, or that God plans things through natural ways! But maybe we need a more technical definitition.
The why of ice floating is because water reaches its densest point at 4 degrees Celsius, so sinks up[ and until that point, and which time the molecules appear to start a shifting and reorganization and the water starts to actually get lighter. This means the cold water starts to stay on top as temperatures go below 4 and the ice floats, It also results in a temperature disparity because while the top can get thicker as the water (or ice) gets colder, the ice acts as insulation and slows the freezing. Thus the top of a glacier can be much colder than the bottom, which is below the water.
Chemically, which is probably what is wanted for this article, ice floating has to do with the way the actual bonds form. Her is an excert from the About.com:Chemistry website that best explains it! ” A water molecule is made from one oxygen atom and two hydrogen atoms, strongly joined to each other with covalent bonds. Water molecules are also attracted to each other by weaker chemical bonds (hydrogen bonds) between the positively-charged hydrogen atoms and the negatively-charged oxygen atoms of neighboring water molecules. As water cools below 4°C, the hydrogen bonds adjust to hold the negatively charged oxygen atoms apart. This produces a crystal lattice, which is commonly known as ‘ice’.”
It is like connecting “V’s” with the space in between and also explains why ice expands as it form. The expansion results in less weight per volume, and makes the ice float. Sounds complex? It can be, but doesn’t have to. This is actually something that people wondered about for ages and wasn’t understood until chemistry was able to understand atoms and bonding, if it actually does!
You can always go with the 4 year old’s explanation and enjoy the fact that it does!
