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Audio 0:06:38.049121
- Formal charges: located on “appropriate atoms”
- Audio 0:10:37.025317
- Per atom, to calculate formal charge, you take the valence electrons minus the electrons on it minus the number of pairs on it.

Audio 0:19:11.165662
Resonance structures must have the same connectivity.
- Only electron positions can change.
Resonance structures must have the same number of electrons.
Second row elements have a maximum of eight electrons.
- Bonding and nonbonding
- Third row can have expanded octet
Formal charges must total the same.
- Better structures have fewer formal charges.
- Better structures have smaller formal charges.
- Better structures have the negative formal charge on the more electronegative atom.

Audio 0:21:06.805441
The exceptions:
Expanded octets:
- Molecules or ions with more than eight electrons around an atom
- Involve the nonmetal elements located in the 3rd period and below
Nonmetals (3rd period down in the periodic table) follow the octet rule when they are not the “center” atom.
- The center atom is the atom in the molecule where the other elements individually bond to (attach).
- When they are the center atom, they can accommodate more than eight electrons.
Using empty valence d orbitals that are predicted by quantum theory
Odd-electron species (free radicals or radicals):
Molecules or ions with an odd number of electrons
- Legitimate Lewis structures cannot be written for they do not meet the “octet rule” as required by the Lewis model.
- Example: NO
  - Has 11 valence electrons
  - Distribution of 11 electrons cannot meet the criteria under the Lewis model.
  - NO does exist as a molecule.
    - The Lewis model is not sophisticated enough to work for an odd number of electron compounds.
Audio 0:22:20.060270
Incomplete octets:
- Elements (specifically metalloids and H atom) whose tendency is not to have a complete octet
  - H can only accompany two electrons (duet).
  - Boron (metalloid)
    - Prefer 6 electrons than 8 electrons

What is the formal charge on the sulfur for best structure for the sulfate anion, SO4^2-?
- Audio 0:27:21.796062
- Most people said plus 2, but the answer is actually 0

Audio 0:32:36.686918
Chemical reactions involve breaking bonds in reactant molecules and making new bonds to create the products.
The change in energy for a reaction can be estimated by comparing the cost of breaking old bonds to the energy released from making new bonds.
The amount of energy, in the gaseous state, that it takes to break one mole of a bond in a compound is called the bond energy.
Audio 0:34:03.982413
The energy change required to break a particular bond in one mole of gaseous molecules is the bond energy

Audio 0:36:20.771621
In general, the more electrons two atoms share, the stronger the covalent bond.
- For comparison of bonds between like atoms
- C≡C (837 kJ) > C═C (611 kJ) > C—C (347 kJ)
- C≡N (891 kJ) > C ═ N (615 kJ) > C—N (305 kJ)
In general, the shorter the covalent bond, the stronger the bond.
- For comparison of bonds between like atoms
- Br—F (237 kJ) > Br—Cl (218 kJ) > Br—Br (193 kJ)
- Bonds get weaker down the column.
- Bonds get stronger across the period.

Audio 0:39:20.498710
Lewis theory predicts that the more electrons two atoms share, the stronger the bond.
- Single bond < Double bond < Triple bond
- Lewis theory would predict that double bonds are twice as strong as single bonds, but the reality is they are less than twice as strong.
Bond strength is measured by how much energy must be added into the bond to break it in half.

Audio 0:40:57.263317
Lewis theory predicts that the more electrons two atoms share, the shorter the bond should be.
- When comparing bonds to like atoms
Bond length is determined by measuring the distance between the nuclei of bonded atoms.
In general, triple bonds are shorter than double bonds, and double bonds are shorter than single bonds.

Audio 0:42:20.387950
The distance between the nuclei of bonded atoms is called the bond length.
Because the actual bond length depends on the other atoms around the bond, we often use the average bond length.
- Averaged for similar bonds from many compounds

Term	Definition
bond energy	the amount of energy, in the gaseous state, that it takes to break one mole of a bond in a compound
bond strength	measured by how much energy must be added into the bond to break it in half
bond length	determined by measuring the distance between the nuclei of bonded atoms
as bonds get longer they get _	weaker
bonds get _ down a column and _ across a period	weaker / stronger