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Why does water expand when cooled, unlike other substances which contract when...
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Water's uniqueness arises from the fact that the water molecule is polar. The orientation of the two smaller hydrogen atoms is such that they occupy one side of the larger oxygen atom. Because the water molecule is held together by a covalent bond, the electrons, although being shared between the oxygen and hydrogens, tend to congregate nearer the oxygen side of the molecule. So one side of the molecule is slightly negative, resulting in the other side being slightly positive.
Because each water molecule is polar, the interaction between them allows for a hydrogen bond to be created, whereby the negative end of one molecule aligns with the positive end of another. In liquid form, the molecules bounce off each other, but when water cools, the polarity and hydrogen bonds orient the molecules in a rigid pattern, where they are actually further apart from each other than in a liquid state. On a macroscopic level, we see then that water expands rather than contracts when cooling into ice.
Posted by enotechris on November 17, 2009 at 12:30 AM (Answer #1)
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the water molecules have the simplist atom that is hydrogen and easily compressable essential element oxygen. hydrogen has the tendensy to occopy more volume under low temperatures than the other elements.so with hydrogen oxygen also does the same.
Posted by alphadav on November 16, 2009 at 10:33 PM (Answer #2)
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