Hybridization and Resonance

Hybridization is the idea that atomic orbitals fuse to form newly hybridized orbitals, which in turn, influences molecular geometry and bonding properties. Hybridization is also an expansion of the valence bond theory. It is found by counting the number of electron domains around the central atom, which determines the number of hybrid orbitals are required. It uses the sub-levels: s, p, d, f. S has one orbital, p has three, d has five, and f has seven.

Hybridization looks similar to locations of electrons, but the amount of space in each sub-level is counting the number of orbitals, not the number of electrons. More information can be found here.

The resonance of a molecule or ion were the bond aren't all the same (all either single, double, or triple) and the other bonded atoms can take the bond that is being moved, were the double or triples bonds are can switch. Basically the Lewis dot structure of a molecule or ion can be drawn in multiple ways.

Carbon trioxide had resonance

The structure with the mean resonance is called the resonance hybrid. This is the most accurate form of the molecule or ion. It equalizes bond length and strength. More infomation if resonance can be found here.

VSEPR

Valence Shell Electron Pair Repulsion Theory (VSEPR) is used to predict the molecular shape of a molecule. Unlike a Lewis Dot Structure, VSEPR is in three dimensions, and thus, is more accurate; however, takes longer to find.

Nitrogen trioxide 

The wedges and lines show that the bonds move towards or away form you, thus giving the bond it's 3-D shape. The shape of a molecule determines how it acts towards other molecules. The example given above is polar, so the molecule has a charge and reacts differently than a molecule that is non-polar would. Each shape also had a unique electron geometry, which depends on its number of electron domains around its central atom. The example is tetrahedral, because their is four electron domains around the nitrogen, three bonds and one pair.

More information found here and here.

Lewis Dot Stucture

No more ionic bonds, and its terrible. This unit is over how covalent bonds bonds look. This can be done on a two dimensional plane, called a Lewis Dot Structure. The structure tells you what atoms have electrons and which atoms share electrons with other atoms.

The dots next to each elements tell the number of electrons that stay next to each element. The lines represent two electrons that are shared between elements. The total number of electrons in the structure have to equal the total number of valence electrons of the elements. The number of bonds needed can be found using a have, need, share method.

More information on Lewis Dot Structure here and here.