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Answer:
The reason why ice is lighter than water is that a certain mass of ice
occupies more space than the same mass of water. This is related to
“hydrogen bonding”.
Hydrogen bonding
A water molecule is composed of two hydrogen atoms (H) and one oxygen
atom (O). The atoms of hydrogen and oxygen are bound by sharing their
electrons with one another. This bond is called a “covalent bond”.
However, since oxygen atoms pull electrons more strongly than hydrogen
atoms, the oxygen atom in a water molecule has a slightly negative
charge and the hydrogen atoms have a slightly positive charge. So
adjacent water molecules are attracted
to one another through the
slightly negatively charged oxygen atoms and
the slightly positively
charged hydrogen atoms. This interaction is called “hydrogen bonding”.
Hydrogen bonding is much weaker than covalent bonding, however, this
type of bonding has a large total effect because there are so many
hydrogen bonds.
Structure of ice and water
Ice has a diamond structure due to the hydrogen bonding. Water does not
have such an orderly structure, but water molecules are squeezed close
to one another because of the hydrogen bonding.
Take a look at the actual structures of ice and
water (see pictures below, pictures are kindly donated
by
MathMol).
The red balls represent oxygen atoms, and the while balls represent
hydrogen atoms.
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Ice |
Water |
There is more space in ice than in water! This is the reason why ice
is lighter than water. Therefore, ice can float on water.
Acknowledgement
MathMol
There is a more detailed explanation about the characteristics of
water in this website. We referred to part of this website when we
created this article.
This article is translated by Chemistryquestion.com from the original article in Chemistryquestion.jp. Please let us know if you find any errors.
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