What is the Octet Rule, a Bohr Diagram, and Lewis Dot Diagram?

The Octet rule states that atoms will lose, gain, or share electrons to achieve the electron configuration closest to the nearest noble gas. Every element has one electron more than the one before. When it has 8 in one shell it is full. If it has 9 then one electron goes to the next outer shell. The atomic number lists the amount of electrons a stable atom of an element has.

Source: http://groups.molbiosci.northwestern.edu/holmgren/Glossary/Definitions/Def-O/octet_rule.html

A Bohr diagram is a simplified model to represent atoms. It was designed by the physicist Niel Bohr. In the center is the nucleus, where the static protons and neutrons reside. On the outside, in the surrounding circles representing electron shells where the electrons float around. The Bohr diagram shows difference in charges by having a plus sign for a positive charge, a minus sign for a negative one, and none for no charge.The top illustration shows what it looks like. If there was a neutron it would be in the center with no charge.

Source: http://homepages.ius.edu/GKIRCHNE/Chem.htm

A Lewis Dot Diagram shows the bonding of atoms within a molecule. In the center is the abbreviation of the element. Surrounding it are dots each representing the valance or outer electrons of an element. The central element is the one with the largest amount of electrons or the largest atom. Around the atom go the other elements within the molecule. You place them according to electrons they share with the central atom. (This means that every bond shares two electrons.)

Source: http://en.wikipedia.org/wiki/Lewis_dot
            http://antoine.frostburg.edu/chem/senese/101/bonds/faq/simple-lewis-structures.shtml