Molecule
Molecule In chemistry, the molecule is the smallest indivisible portion of a pure compound that retains a set of unique chemical and physical properties. A molecule consists of two or more atoms bonded together. One might wish to view molecules analogically; as a word: the word "can" could be an example of a molecule; if "e" is added, one obtains "cane" -- in a similar fashion, H20 is the water molecule; whereas, (CH20)3 is a form of sugar molecule.
Most molecules are much too small to be seen with the naked eye, but there are exceptions. A grain of salt, or the diamond on an engagement ring, are giant crystal lattices, repetitive molecules with atomic bonding (usually ionic bonding) connecting the entire structure.
A property of molecules is the integer ratio of the elements that constitute the compound, the empirical formula. For example, in their pure forms, water is always composed of a 2:1 ratio of hydrogen to oxygen, and ethyl alcohol or ethanol is always composed of carbon, hydrogen, and oxygen in a 2:6:1 ratio. However, this does not determine the kind of molecule uniquely - dimethyl ether has the same ratio as ethanol, for instance. Molecules with the same atoms in different arrangements are called isomers.