An Ironclad Molecular Bond:
Hydrogen and oxygen have so great an affinity for each other that,given even the slightest nudge,they come together violently,forming water and releasing great quantities of energy. In 1937 the huge dirigible Hindenburg exploited over Lakehurst,New Jersey,when its Hydrogen,ignited by a spark,fused with the oxygen in the air;amid the explosive release of energy,water was produced.
Conversly,it takes a great deal of energy to split water into its components. In fact,in ancient timer water was considered a basic,indestructible element of the universe. Not until Henry Cavendish started the scientific community in 1783 by synthesizing the water molecule did it become clear that the sunstance is actually a compound made up one part oxygen and two parts of hydrogen.
The reason water was long thought to be a single element was that the sturdy water molecule remains intact even when frozen solid or heated to temperatures at which many other compounds disintegrate. For the atoms of the water molecule are laced together by powerful bonds,which can be severed only by the most aggressive agents-such as electric energy or certain chemicals. One such chemicals is potassium is dropped into water,it pulls the molecules apart so violently that the containor of water may actually explode.
A Network of Nimble Molecules:
Once formed,water molecules join with each other in a unique way,creating the liquid latticework shown in the diagram at far right. The connection between water molecules is called a hydrogen bond. When water is in the form of ice,these bonds hold the molecules in a more or less rigid pattern. But in a liquid state this structure gives way to a chaotic moleculer square dance in which groups of molecules take turns whirling about with one another,breaking their bonds,and finding new groups to form partners with.
When water is heated the pace increases until the bonds,no longer able to keep their partners at arm’s length,snap,and the molecules fly off as gas. It is these bonds that pull water’s surface into a taut sheet-a phenomenon known as surface tension.