You probably take water for granted because it is so common, but water is an very unusual substance.
Its most spectacular property is that ice floats on water. You probably think, thats no big deal, but water is almost the only substance in the universe for which the solid floats in the liquid!
In nature, electric charges of the same sign repel, and electric charges of different sites attract. The bond that is formed is called a hydrogen bond.
Why does ice melt when the melting temperature is reached?
In nature, every atom or molecule undergoes a vibration or jiggling, because it has termal energy.
The strenght of vibration increases with temperature! When the temperature is high enough, the ice melts, because the thermal vibration is so strong that the hydrogen bonds are broken.
In the ice structure, the molecules have relatively open arangement . When the ice melts, the molecules become free to pack together more closely. THAT IS WHY WATER IS DENSER THAN ICE :).
Take a glass of water and look at it now. Perhaps the strangest thing about this colourless liquid is that it is liquid at all.
If water followed the rules, you would see nothing in that glass and our planet would have no oceans at all. All of the water on Earth should exist at vapour : part of a thick, muggy atmosphere sitting above an inhospitable, bonedry surface!
I dont really know how to end the post so: THE END :P
I hope you learned something new ;)