Who first proposed that matter is made up of atoms the smallest particles of matter?
Democritus and/or his mentor Leucippus came up with the idea, but for them it was a really lucky guess; they had no evidence for this (and they were completely wrong about what the atoms were actually like).
The modern concept of atoms dates back to John Dalton, who unlike them had an actual reason for suspecting this was true.
Describe the discovery that demonstrate for the first time that atoms are not the smallest particles of matter?
No, atoms are not the smallest particles of matter. Atoms are the smallest pieces of a chemical element, but atoms are made of even smaller particles. We know that neutrons, protons and electrons make up atoms. And there are even smaller particles when we begin to look at what is called the particle zoo.
Small matter, this can be answered depending on how you look at it, originally atoms were named because they were believed to be the smallest particle of matter and cannot be split anymore but scientists now know that subatomic particles exist such as quarks. They and others are building blocks of matter. http://www.nyu.edu/pages/mathmol/textbook/atoms.html A particle is a very small piece of matter. Particles are part of atoms. Atoms are the smallest unit of all substances.
Are molecules the smallest subdivision of matter that can retain a substance and its chemical properties?
When atoms were first discovered it was believed that they were, but now we know that they are not. Atoms contain sub-atomic particles called electrons, protons and neutrons and these sub-atomic particles are also made up of other smaller particles. It is not yet known what the smallest particle is because all of the particles that have been found can be divided into smaller particles.
An atom is not the smallest particle of matter. Atoms are made up of protons, neutrons and electrons, all of which are (obviously!) smaller than the atom itself. Electrons are regarded as fundamental particles, but protons and neutrons are believed to be composed of three quarks, held together by gluons. All of these particles are millions of times smaller than atoms, and there is no guarantee that they don't comprise even smaller particles...
No,it is not the smallest one because atoms are smaller than molecule,again sub atomic particles like neutron,proton,electron,positron etc are even smaller than atoms. No, a quark is the smallest particle of matter that we know of. Quarks make up many small particles, such as protons, neutrons, and electrons, which make up atoms. Which in turn, make up molecules.
No, this is a misconception. Atoms are the smallest particles which have the same properties of an element. Smaller still, the nucleus of the atom, it contains the protons and neutrons of the atom, and electrons orbit around the nucleus. Protons and neutrons are made out of even smaller particle, quarks.