Organic Chemistry Introduction

Experiment in Reverse Psychology

• The presenter used a reverse psychology technique by telling viewers not to watch the video to see if they would watch it anyway.
• Asked viewers to comment on why they chose to watch the video.

Lewis Structures

Periodic Table Groups and Bonds

• Group 1 elements (e.g., H, Li, Na): 1 valence electron, form 1 bond
• Group 2 elements (e.g., Be): 2 valence electrons, form 2 bonds
• Group 3A elements (e.g., B): 3 valence electrons, form 3 bonds (4 bonds if negatively charged)
• Group 4A elements (e.g., C): 4 valence electrons, form 4 bonds
• Group 5A elements (e.g., N): 5 valence electrons, form 3 bonds (neutral state)
• Group 6A elements (e.g., O): 6 valence electrons, form 2 bonds
• Group 7A elements (e.g., F, Cl, Br, I): 7 valence electrons, form 1 bond
• Elements tend to form bonds to match their valence electrons up to 8 (octet rule).

Example Molecules

• Ammonia (NH3): Nitrogen has 1 lone pair, 3 bonds
• Water (H2O): Oxygen has 2 lone pairs, 2 bonds
• Hydroxide (OH-): Oxygen has 3 lone pairs, 1 bond (negative charge)
• Methane (CH4): Carbon has 4 bonds

Alkanes and Structure Examples

• Methane (CH4), Ethane (C2H6), Propane (C3H8): Single bonds, saturated with hydrogen
• C2H4 (Ethene/Alkene): Double bond
• C2H2 (Ethyne/Alkyne): Triple bond
• Bond strength and length: Triple bonds are strongest and shortest; single bonds are longest and weakest.

Naming Organic Compounds

Alkanes, Alkenes, and Alkynes

• Methane: CH4
• Ethane: C2H6
• Ethene (Alkene): C2H4
• Ethyne (Alkyne): C2H2
• Naming rule: CnH2n+2 (Alkane), CnH2n (Alkene), CnH2n-2 (Alkyne)

Functional Groups and Naming

• Alcohol: -OH group (e.g. Methanol: CH3OH)
• Ether: R-O-R' (e.g. Dimethyl ether: CH3OCH3)
• Ketone: R-CO-R' (e.g. Propanone)
• Aldehyde: R-CHO (e.g. Ethanal)
• Carboxylic Acid: R-COOH (e.g. Propanoic acid)
• Ester: R-COO-R' (e.g. Methyl ethanoate)
• Amine: R-NH2 (e.g. Ethylamine)
• Amide: R-CONH2 (e.g. Butanamide)
• Nitrile, Acid Chloride, Benzene Ring: Other important groups

Formal Charge and Resonance Structures

Calculating Formal Charge

• Formula: Valence electrons - (bonds + dots)
• Example: Oxygen typically has 6 valence electrons

Resonance Structures

• Allows movement of electrons (not atoms)
• Shows different possible structures of a molecule
• Examples: Acetate ion, Amide
• Major vs. Minor Resonance Structures: More stable ones are major contributors

Organic Chemistry Nomenclature (IUPAC)

• Examples:
  • 3-methyl hexane
  • 5-ethyl-4-methyl octane
• Count longest carbon chain and identify substituents with lowest numbers

Additional Resources

• Link provided in the description to detailed videos for further learning