Why are atoms mostly empty space?

Question

Okay so this question is: In the early 1900s, Ernest Rutherford set up an experiment to study the atom. he bombarded thin metal sheet with protons and neutrons. he found that most of particles got deflected a bit, but some of them bounced back as if bouncing off a brick wall. Waht conclusion came form this experiment?
The answer was: Atoms are mostly empty space... well I didn't understand that much so does anybody mind explaining? I really want to ace an upcoming test!! THANKS!!!

Answer 1

The actual answer is that electrons are constrained to shells around the nucleus of the atom. These shells correspond to allowed energy levels governed by quantum mechanics. It turns out that the allowed energy levels of the electrons put them at a huge distance away from the nucleus of the atom (with respect to the diameter of the nucleus). Other atoms interact only with the outer shells of electrons making it look like the atoms are "solid" whereas they are mainly empty space. A poor analogy would be the solar system. The planets are very far away from the sun and the solar system is mainly empty space.

Answer 2

You can think of an atom and its particles as a mucher smaller fan. When off the fan's diameter is mostly empty space. When turned on the fan's empty space seems to be filled with the moving propellers. This is the same thing with an atom. The particles are so small and so fast it may seem that an atom is completly solid but this is false. The fact that atoms are pretty much empty space however doesn't mean we can move through walls. The particles are moving so fast they are virtually solid. Put your hand through a fan and you will understand what I mean. In order to move through a wall lets say, we would have to line up all of our body's subparticles to match that of the wall which right now is impossible to fathom.

Answer 3

I agree with all answers, but specifically I would like to mention two things. First the Rutherford experiment decides the concentration of positive charge and therefore mass of atom in a very small distance (10^5 times smaller)compared to atomic dimensions. As you go very near the spherical charge distribution the electric field increases but if you enter inside it the electric field will decrease. So Thomson model will not be able to describe correctly the distance of closest approach correctly for alpha particle of a given energy. So alpha particle scattering decided the size of the nucleus.



Second thing to understand about feeling of the hardness of matter, when one piece of matter tries to inter-penetrate the other, in spite of the empty space both contain, one must take recourse to quantum nature of electron. in atom electron cannot be considered like a point particle present all the time in the classical orbit, but as a probability cloud whose probability of finding any where other than orbit is not zero only on orbit it is maximum. So quantum mechanically speaking it is not empty space but electron-space. So when two pieces of matter interpenetrate two electrons tend to occupy the same quantum state, being Fermion this is not allowed to happen giving rise to some kind of repulsive force of quantum origin arising due to Pauli Exclusion, principle comes into play.

Answer 4

You are half correct. If you think of atoms the way they taught us in Elementary then if you were the size of the nucleus then the electron would be about 3 miles away from you or some such. However, atoms aren't like that model according to recent theories (or proof i'm not sure) Electrons are more fizzing about around the nucleus. they are here one sec, then somewhere else or something like that. I can't remember exactly.

Answer 5

If you threw a ball through a patch of trees, or a picket fence, and almost all of the time the ball went through and came out the other side, you would realize that there was a lot of non-tree or non-picket area through which the ball traveled.



The same is true of Rutherford firing particles at various foils (or did he just use gold?).