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Free online chemistry
lesson for elementary school, middle school and high school.
All materials around us are made up of microscopic particles. These
tiny particles of matter that are invisible to the naked eye are called
These molecules are so small
that the conventional optical microscopes are not powerful enough to
To give an order of magnitude, the smallest molecules are about one
million times smaller than a grain of sand.
However, there are thousands if
not millions of kinds of molecules that have different sizes and shapes.
These molecules are present in all the matters that surround us like
gases, liquids or solids. They are also present in the materials that
constitute living beings but yet the molecules are not living organisms
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