Atomic Structure
An atom is the basic building block of all matter and is composed of 3 principle particles: protons, neutrons and electrons. Each atom is made up of a combination of these elementary particles. Protons are positively charged and resides in the nucleus of an atom. The neutron is of a neutral charge (not positive or negative) and also resides in the nucleus of an atom. The electron is much much smaller than the proton or neutron particles, and remains outside of the nucleus surrounding the center as various energy levels.
Centrifugal Force
Since the proton and electron are attracted to one another because of their opposite charges, what is there to keep the two from crashing into one another? Well, the centrifugal force of the rotating electron around the center, or nucleus, keeps the two from colliding. The same force that works on the planets in our solar system from colliding with the sun also works within and forms the atomic structure.
Electron Cloud
Most of us have seen an illustration of electrons around the nucleus of the atom represented as tiny dots. This demonstration is actually a bit misleading. It is actually more correct to portray the electrons around a nucleus as a cloud. Electrons have many of the same properties as a wave and thus are more similar to a beam of light than they are being represented as a dot circling the atomic center. An electron is a wave that surrounds the center of an atom as an electron cloud.