Organic I

• Covalent Bonding & Molecular Shape involve the study of the structure, properties, composition, reactions, and preparation of carbon-containing compounds.
• Whenever atoms are involved in resonance that has one or more contributing structures involving a π bond to that atom, the atoms must be sp2 hybridized.
• On rare occasions, the atoms can be sp hybridized, but never sp3 hybridized.
• Each bond consists of 2 valence electrons.
• Be sure to use the total number of valence electrons when adding lone pairs.
• Chemical bonds form via valence electrons.
• In Covalent Bonding using VB + MO Theory, sigma bonds (s) are formed by atomic orbitals involved in three hybridization states of atoms ( sp 3 , sp 2 , and s p ), and pi bonds (p) are formed by overlapping atomic p orbitals.
• Valence Bond (VB) Theory states that bonds are created by the overlap of atomic orbitals on adjacent atoms.
• Electrons in molecules exist in molecular orbitals, just as electrons in atoms exist in atomic orbitals.
• A combined valence bond and molecular orbital theory approach to covalent bonding, known as Covalent Bonding using VB + MO Theory, is commonly used in organic chemistry.
• Valence-Shell Electron-Pair Repulsion (VSEPR) Theory is based on the idea that electron groups repel each other.
• A Lewis structure is a representation of a molecule's electron structure, where electrons are represented by dots and bonds are represented by lines.
• Hybrid orbitals then overlap with orbitals on other atoms to form bonds in VB Theory.
• VSEPR Theory predicts molecular geometries and bond angles of chemical structures.
• Atomic orbitals on the same atom combine to form hybrid orbitals (sp, sp 2 , and sp 3 ) in VB Theory.
• Molecular dipole moment determines whether a molecule is polar or nonpolar.
• Tetrahedral geometry has bond angles of 109.5°, trigonal planar geometry has bond angles of 120°, and linear geometry has bond angles of 180°.
• Functional groups allow the organization of organic molecules, are sites of characteristic chemical reactions, and are the basis for naming organic compounds.
• Pauling’s Electronegativity Scale: A measure of an atom’s attraction for electrons that it shares with another atom in a chemical bond.
• Bond Dipole Moment (μ): Measure of the polarity of a covalent bond.
• Exceptions to octet rule: Electron-deficient atoms, odd-electron species, expanded valence shells, and period 3 and below.
• Octet Rule: Group 1A to 7A elements react to achieve an outer shell of eight valence electrons.
• Common Bonding Patterns in Neutral Molecules: Hydrogen has 1 bond, carbon has 4 bonds and no lone pairs, nitrogen has 3 bonds and 1 lone pair, oxygen has 2 bonds and 2 lone pairs, halogens have 1 bond and 3 lone pairs.
• Formal charges: Valence electrons - (all unshared electrons + 1/2 shared electrons).
• All resonance structures must have the same number of valence electrons
• Common errors include violating the octet rule, having a carbon atom with 5 bonds, and incorrect arrow placement
• Curved arrows show the redistribution of valence electrons between contributing structures
• The relative importance of resonance structures is determined by filled valence shells, maximum number of covalent bonds, and least separation of unlike charges
• The real molecule or ion is a resonance hybrid
• Tail of arrow shows where electrons are coming from
• Never move atoms, only move lone pairs and pi bonds
• All resonance structures must obey the rules of covalent bonding
• Third-period elements may be drawn indicating up to 12 electrons in their valence shells
• All resonance structures must have the same number of paired and unpaired electrons
• Individual Lewis structures are called contributing structures (or resonance structures)
• does 1s2 orbitals participate in chemical bonding?

  No.
• atomic number is equal to what?

  number of electrons
• How are bonds created?

  overlap of atomic orbitals on adjacent atoms
• atomic orbitals (s and p) on the same atom combine to form hybrid orbitals

  (sp, sp2,sp3)
• if i have 4 atomic orbitals, how many hybridized orbitals can I form?

  4