>I heard from my teacher, that its not possible to see Atoms, because they are "energy levels"...<

With respect to your teacher, on the assumption that you have correctly understood and reported him/her, it is highly arguable whether it is meaningful to define atoms as energy levels.

Even if it were meaningful, then how would it follow that anything whatsoever is anything but energy levels? Seen any good hard objects lately that did not consist of those energy levels called atoms? This argument tempts one into the fallacy of composition, but at what stage does a structure of "energy level atoms" comprise a real, visible honest-to-goodness object?

And if we can see the energy levels that comprise hard-boiled eggs, porcelain cups, cricket balls and Uluru, then why can't we see the energy levels of their atoms? And following from the conclusion from that, what is "seeing" anyway?

I suggest that you compose a tactful, friendly, carefully worded request along those lines, that your teacher clarify some such relevant points.

And Re the "visibility" of atoms :

http://en.wikipedia.org/wiki/Field_emission_microscopy

Such microscope tubes are sold as a physics teaching

apparatus since the 30ties, I think You could purchase

one for some hundred $s.

Georg

Sorry, iam from germany so i used the wrong word. For example i saw some pictures of atoms but i couldn't imagine what this  atoms are. Is it the electrons or protons which i can sse on some photos or something else. that was my question. Also because I'm in the 12. grade and we are learning that atoms,electrons... are like waves( maybe the wrong word) not like a ball.

"Waves" is the right word.  The problem is that the concepts that you are dealing with are confusing and cannot simply be expressed in everyday words. In fact, some people think that we simply cannot understand them in everyday senses at all. For more detailed ideas of the subject, you will have to work through writings on quantum theory.

Part of the problem is that on the scale of the size of atoms and below, there are two basic ways of looking at an object: as a wave packet of high frequency, or as an object. By looking at an object in the one way we affect its reality in the other way and we cannot measure it in both ways at extremely accurately. The more accurately we try to measure the position of the object, the less precisely we can measure its wavelength, and the more precisely we measure the wavelength, the more vague its position becomes.

I cannot put that more precisely here and now; you will have to read some material on quantum theory if you need to understand that.

However, some of the consequences of those facts about what things "look like" on the atomic and subatomic scale permit us to "see" various things about atoms, electrons and other particles, up to certain limits of accuracy or fuzziness in various ways.  We can for example use field effect microscopes to "see" individual atoms and molecules under suitable conditions, and for the last twenty years or so, we can see a great deal more detail than before with the STEM (scanning transmission electron microscope)  and since then with AFM (atomic force microscope).

Although there is some philosophical argument about whether we could call that "seeing" atoms, my personal opinion is that the question is a non-problem at practical levels. The short answer is that what we do looks very like seeing, behaves like seeing, and works like seeing. If anyone is to deny that it amounts to seeing, then he will have to redefine "seeing", rather than deny our definition of what such "microscopes" do as "seeing".

There is a great deal of written material on such subjects on line and in print, and I hope that what I have said can give you some idea of the basic ideas.