An ancient Greek we're the first to use the word atom which means indivusble, to describe the smallest particle of any substance therefore an atom is the smallest particle of an element which can take part in a chemical reaction in order words an atom of an element that can ever exist and still possess the chemical properties of that element
Molecules
Most atom can not exist alone they generally bond with other atom to form molecules. Molecules may be made up of atoms of the same element or of different elements
The number of atoms in each molecules of an element is called the atimicity of the element these number is usually small
Most gasgous element lirk oxygen and chlorine are diatomic that is the molecules consists of two atoms others like phosphorus and sulphur exist as polyatomic molecules
Therefore a molecule is the smallest particle of a substance that can normally exist alone and still retain the chemical properties of the substance be it an element or a compound.
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