Objectives (the things you need to know and be able to do):
You need to know that:
*Atoms are far too small to see.
*Atoms combine to make molecules.

You need to be able to:
*Diagram the arrangement of particles in the three physical states of matter (solid, liquid, gas).
*Describe the limitations of using models to represent atoms.
*Learn how our knowledge of the structure of matter developed.

Information:

"The scanning tunneling microscope has a small probe which actually more like
"feels" the size of the atoms and reads this out on a computer screen. The
probe can pick up individual atoms. IBM used a STM years ago to spell I B M
with uranium atoms and took a picture of it. But one does not actually
directly "see" the atoms."
Peter Faletra Ph.D.
Assistant Director
Science Education
Office of Science
Department of Energy
 

All particles of matter are in motion.

Atoms are made up of the positively charged Proton and uncharged Neutron (in the nucleus)
and the negatively charged electron (in the energy shell or orbital).
Particles in solids are closer, and move much slower, than particles in a liquid of the same substance (Think Ice and liquid water). Likewise, particles of liquids are much closer, and move much more slowly, than gasses of the same substance (think liquid water and water vapor or steam).

Depending on the amount of energy they have, atoms will be in one of three phases of matter: solid, liquid, or gas.
The particles in a gas move very fast because they are high energy! Solids don't tend to move much because their atoms are low energy, liquids are somewhere inbetween.

Ok so yes, there is a 4th phase of matter (plasma) but we are not dealing with it in this class, just the 3 physical states of matter.
 

If you were at American Fork Jr High School and you could take a nucleus of an atom, and enlarge it to the size of a marble, the closest electron would be out orbiting around the cemetery. As you can see, atoms are mostly empty space.