Unit 2 Lewis structure

Calculate bond order

(1+2+1)/3=1.33 Note I am not kidding all the bonds in one of the structures are all equal. This is because they are all averages of the same bond in the resonance structure right next to it.

Expanded octet

An exception to the octet rule that permits atoms in the third row or lower on the periodic table to have more than eight electrons in a Lewis structure. This is because they have open d sub levels that can be filled up

Note

Bond angles get smaller when there are uncharted electron pairs that exert more repulsion than shared pairs. If a question asks for shape, it only wants the broader geometry

Trick to find hybridization

Find the total amount of domains 2-sp 3-sp^2 4-sp^3 5-sp^3d 6-sp^3d^2

CH4 hybridization

It's orbitals hybridize and become one hybrid orbital that is 1 parts p and 3 parts s or sp^3

CH4 hybridization

Let's focus on the central aroma carbon. We know it only uses it's valence electrons to bond. Let's look at those and their orbitals

Valence Shell Electron Pair Repulsion Theory

Molecules will attain whatever shape keeps the valence electrons of the central atom as far apart from one another as possible

Note

Notice that N2O has both 2 equal resonance structured but but 3 unequal structures

Unequal resonance structures

Resonance structures that can be drawn for a molecule or polyarimic ion but, they are not equally because in order tonintainnesch structure you have to make new types of bonds or rearrange atoms

Molecular geometry vs electron geometry

The main difference between electron geometry and molecular geometry is that electron geometry is found by taking both lone electron pairs and bonds in a molecule whereas molecular geometry is found using only the bonds present in the molecule. Lucky you is that there's no need to memorize all of the geometries and angles because you already did.

Bond order

The strength and length of all the bonds in any set of equal resonance structures are the same: in between the strength and length of the single binds and double binds or single binds and triple bonds. Bond order calculation will tell you the relative length and strength of the resonances. Single binds have bond order of 1, 2 are 2 and 3 are 3. Pick one resonance structure, add opup all the bond orders. Divide that by number of BOND areas. REMEMBER the higher the bond order: the stronger the binds and therefore the shorter the bonds

Lewis electron dot diagram

To mimic the structure of a singular molecule or formula unit or large molecule, you want to draw the Lewis structure.

Polarity

Unbalanced regions of negativity caused by line pairs causes polarity on one end of a molecules

Formal charges

When more than one unequal resonance structure is possible, the determination of the best structure can made based on the formal charges in the structure. The calculation of the formal charge is given by: #valence electrons - (½ shared electrons + lone electrons)

Equall resonance structure

one of the two or more equally valid electron dot structures of a molecule or polyatomic ion. Resonance can only occur when the bond or bonds can be rotated without changing the atoms. These Resonance structures are equall and are thus called equally resonance structures

Hybridization

the mixing of several atomic orbitals to form the same total number of equivalent hybrid orbitals