This video uses animation and introduces Lewis Structures to demonstrate stable and unstable electron configurations to explain the octet rule. The program shows viewers how they can use the periodic table to understand the octet rule. The examples featured in the video will assist students in realizing that elements react so that their electron configuration matches that of the noble elements and that this stable configuration is eight electrons in the outer shell for low atomic number elements.
The octet rule is a chemical rule of thumb that reflects observation that elements tend to bond in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas. The rule is especially applicable to carbon, nitrogen, oxygen, and the halogens, but also to metals such as sodium or magnesium.
The valence electrons can be counted using a Lewis electron dot diagram as shown at the right for carbon dioxide. The electrons shared by the two atoms in a covalent bond are counted twice, once for each atom. In carbon dioxide each oxygen shares four electrons with the central carbon, two (shown in red) from the oxygen itself and two (shown in black) from the carbon. All four of these electrons are counted in both the carbon octet and the oxygen octet.
