Of course chemists had little doubt in the existence of atoms. But they could not determine their masses. All "atomic masses" were relative to that of hydrogen. (And they still are, at least approximately, given that 1/12 of carbon-12 is almost the same.)
To condense that a bit, the idea is roughly that the relative variance goes as ##\sqrt{\frac{1}{n}}## rather than as ##\frac{1}{n}## where n is the number of atoms per smoke particle?
By whom>
Who?
I believe that Max Planck was skeptical of atomic theory until the 1890's. There's a piece here, for example:
This is a very interesting addition to the "story." Especially when combined with
As discussed in David Lindley's book Boltzmann's Atom, The Great Debate That Launched A Revolution In Physics, and above, Einstein explained Brownian Motion using Boltzmann's atomic theory in 1905. The book has the history of the development of these ideas.
Many physicists of the time were not convinced of the existence of atoms. This persisted well into the 1900's. Einstein presented an argument for the existence of atoms, but these things are never proofs. They are simply pieces of evidence that support the existence of atoms. It's not like one day there's suddenly proof and everyone instantaneously becomes convinced.
I suspect even those who did accept the existence of the atom eventually died as well!
Historically the "atomic hypothesis" in the 19th century was much more accepted by chemists, because the then well-established stoichometrics found a very natural explanation from it, i.e., why chemical reactions go in integer proportions involving "elements", which could be (at least roughly) ordered in systems like Mendeleev's "periodic table". Of course, the details are not always that clear. Even today there is some discussion about the correct ordering in some parts (lanthanides and actinides etc.). Nevertheless the idea of "discrete building blocks" was much more natural for chemists than physicists. The latter had more continuum/field theories of matter, including phenomenological thermodynamics, in mind than atomistic ones. That's why the early "atomists", using statistical methods (kinetic theory of gases a la the Bernoullis, Gibbs, Maxwell, Boltzmann et al), had a hard time to convince their more conservative colleagues.
Yes, but the point is that those who remained shared their acceptance of the atom.
No no, Democritus was right. It's not his fault that our atoms are misnamed. Using his terminology, neutrinos and quarks and electrons and so forth are atoms.
For now.
He certainly managed to tidy things up a lot but IMO Lavoisier more or less introduced the idea of atoms before he had his head removed by those nasty French Revolutionaries in 1794. The experimental evidence didn't all arrive at once and it's a matter of opinion what constituted an actual proof. The existence of isotopes didn't exactly help things.
Dalton generally gets the credit for atomic theory in chemistry, followed closely by Avogadro. Lavoisier is more known for his formulation of the law of mass conservation.
Did Democritus said that one kind of atom can turn into another? In other words, that atoms can be created and destroyed?
To Democritus an atom was the smallest amount of something possible. Neutrinos, quarks, and electrons don't fit this definition. For example the smallest amount of gold is one atom of gold. That part he got right. He thought of these atoms as indivisible. He got that part wrong.
What a loser. ?
I think modern particles are so far from anything he imagined, e.g. in typical states their properties and even their number are undefined, that one can't really say he was right.
I suspect that even if Democritus had come up with the basics of QFT, you'd give him no credit!
Hardly, he's my favourite 5th Century Thracian.
Yes, QM has changed our view of the world a lot. In hindsight, we only have experience with 'clumps' of quantum stuff and can only probe the quantum world by interacting with those clumps. That this led to a theory predicting the probabilities of those interactions (aka observations) is only expected. We are lucky, though, in that mathematical analysis shows it is just an example of a broader class of probabilistic theories than ordinary probability theory and led to the creation of a new area of mathematical investigation called Generalised Probability Theories: