I'm not exactly sure but it's probably: electrons, neutrons, and protons.
The electron is the smallest particle of the atom, in the traditional sense. However, the neutrino is far smaller than the electron, and is thus the smallest particle. You could also argue that the photon, with zero rest mass, is actually the smallest, but that's a quantum mechanics question that seems to be beyond the scope of this question.
An atom is the smallest particle of matter.
An atom is the smallest particle of a substance.
An iron atom is the smallest iron particle that still has the properties of iron.
This particle is the atom.
An atom
An atom is the smallest particle that comprises a chemical element.Source:http://en.wikipedia.org/wiki/Atom
The atom is the smallest known particle.
The smallest particle of an element is called an atom.
The smallest particle in the atom is the electron.
An atom is the smallest particle of a substance.
An atom is a particle, the smallest particle that can exist by itself.
An iron atom is the smallest iron particle that still has the properties of iron.
An atom is the smallest particle of an element that can be uniquely identified as that specific element.Note that this question is different from asking "What is the smallest particle in an atom?" (see related question below). Atoms are composed of smaller particles (protons, electrons, and neutrons), but the smallest thing that has the identity of a specific element is the atom.The smallest particle of an element that still retains all that element's properties is called an ATOM.
atom is the smallest particle of matter
Atoms are NOT the smallest particle- they are the smallest COMPLETE particle. In an atomic reaction, the atoms are broken apart, and release energy.
the atom
An atom
Electron