How do scientists know that atoms exist?

I know this might sound like a ridiculously simple question, but how do scientists actually know about the structure of atoms and their constituent parts? Who proved it? If they're so small, how the hell do they actually know all the stuff seen in chemistry books?

And what do scientists mean when they say they've 'fired' particles in experiments? How can they even do that? How can they 'fire' an electron?

How do we know that the universe is made up of trillions and trillions of these little things called 'atoms'?

Why do you have to hit a base? I'm not talking about creating anything 'new', so to speak; I'm just talking about getting smaller and smaller ad infinitum. There seems to be no logical reason why you couldn't go on dividing forever.

if we do get to a fundamental base particle, then it would very hard to break it into smaller peices, as you need something to break it, but there is nothing smaller...in simple terms, knives can cut things because the knive edge is narrower than the object you are cuting, so it would also be impossible to cut your hair lengthwise, as your hair is very much likely to be narrower than the knives edge?......understand?....I'm not very good at explaining things....

It wouldn't just be 'very hard', it would be - by definition - impossible. :P

I know this might sound like a ridiculously simple question, but how do scientists actually know about the structure of atoms and their constituent parts? Who proved it? If they're so small, how the hell do they actually know all the stuff seen in chemistry books?

And what do scientists mean when they say they've 'fired' particles in experiments? How can they even do that? How can they 'fire' an electron?

How do we know that the universe is made up of trillions and trillions of these little things called 'atoms'?

I thought you couldn't know an atom's exact position and momentum?
[Heisenberg Uncertainty Principle]

they don't know its a guess and a representation of what they believe just like religion, its something they want you to believe just like what does 2 + 2 = ? 4 or 5 just because your told and fed that it does add you to 4 doesn't mean that its right

It's a very good question actually! I have often wondered how they managed to surmise the exact nature of atoms and molecules. I mean, they can even measure the length of certain covalent bonds!

However, I know the way they managed to draw these conclusions is incredibly complex and not something I could easily understand at this stage, so I don't give it much thought. Technically since I haven't seen the proof with my own eyes, I only believe that atoms exist, but it doesn't really matter. They're insignificant in terms of my life. At the end of the day, my knowledge on atoms is only really useful for getting good marks in exams.

Electron microsopes and Scanning tunnelling microscopes can be used to make observations on the atomic scale.

We can't actually see inside them but Rutherford's alpha scattering investigations shows that there is a heavy (but tiny) positive mass in the centre with most of the atom being empty space.
It's just a model, it isn't actually confirmed with real physical observations of the internal atom itself but the model works and fits all scientific theory.

You make it sound like that's easy. I don't know about you, but I certainly don't have a lab with that kind of facility in my bedroom now (this is real life, not Dexter's Laboratory)

Atoms have been proven with absolute certainty since the Electron microscope, and in 1827 with Brownian motion.

Don't reply unless you know what you are talking about.

have you personally seen them? or you believe what you been told and has been published

have you personally seen them? or you believe what you been told and has been published

I CAN DO THAT! I dunno if I want to be responsible for the OPs exploding head though =P

Yeh, according to science, the wings of the bees are too light, and the bee are too heavy fot them to be able to fly.

Do it! 5 points for every tsr user you kill due to head explosions, -5 points if you kill a kitten though