molecule
an atom of sugar
The smallest part of any chemical element that can exist is an atom of that element. The smallest part of a chemical compound that can exist is a molecule of that compound.
The smallest value is 0.
An 'atom' is the smallest unit that ANY element can be divided up into. An 'atom' of silver is the smallest piece of silver that there can be, similarly an 'atom' of oxygen is the smallest bit of oxygen that can be. Thus all elements are made of 'atoms'.
molecule
Cell
A monosaccharide (a molecule of sugar).
There is no smallest number and, since it does not exist, it cannot be used for anything!
The pawn.
Atoms
smartie
We could say what the second smallest piece of matter if we knew what the smallest piece of matter was. Since the smallest pieces of matter known are quarks-down, strange and bottom have the lowest charge -3, they can be regarded as the first, second and third smallest particles.