What is the smallest unit of matter which substances can be divided without loosing its basic properties?

Answer 1

Molecule is the smallest identity of a substance/compound
An Atom is the smallest identity of an element

Answer 2

I already answered a question simliar to this one, and so I'll give the same response: To exist is to have properties, whether it be mass, spin, charge, frequency, phase, etc. Size is another such property, but even if something had no size at all, it still could have other attributes, such as phase, which is a pretty abstract thing but nonetheless can have a real presence. Ordinary matter that we're familiar with does have a lower bound, called Planck Scale (see wiki article) which is considered by many physicists as the boundary between ordinary matter, and something currently beyond physical understanding. String theorists believe that vibrating strings reside in compactified dimensions in the order of Planck Length, or about 10^-35 m, but other theories being proposed probe even smaller features. And they are very exotic. Nevertheless, however exotic "existence" may be at those tiny dimensions, even as "ordinary properties" are squeezed out at this scale, it does not rule out the possibility of other realms of physical existence at those "so small that it can't possibly exist" scales. It's just not like anything you and I would be familiar with. For example, ordered time may even cease to exist at those scales.

Answer 3

elements can be reduced to atoms as they only have one type of atom. For example: Hydrogen is made of nothing but hydrogen atoms.

Compounds can be reduced to molecule (a group of atoms). Eg: Water is two hydrogen atoms and one oxygen atom.

Answer 4

A molecule.

Answer 5

either an atom or a molecule

Answer 6

An electron

Answer 7

depends, if its a compound then a molecule, if it is an element an atom.

Answer 8

molecule