What is organic chemistry?

Organic chemistry is the study of carbon-containing compounds, including hydrocarbons and their derivatives. It focuses on the structure, properties, reactions, and applications of organic molecules.

What is catenation?

Catenation is the ability of carbon atoms to form long chains and rings by bonding with other carbon atoms. This property allows the formation of a vast number of organic compounds.

What was the first organic compound synthesized in a laboratory?

Urea (NH₂CONH₂) was the first organic compound synthesized by Friedrich Wöhler in 1828 from ammonium cyanate, proving that organic compounds can be synthesized from inorganic.

Why is carbon tetravalent?

Carbon has four valence electrons and forms four covalent bonds to complete its octet, making it tetravalent.

What are the three types of hybridization in organic molecules?

• sp³ Hybridization (tetrahedral, 109.5° bond angle) – Example: Methane (CH₄)
• sp² Hybridization (trigonal planar, 120° bond angle) – Example: Ethene (C₂H₄)
• sp Hybridization (linear, 180° bond angle) – Example: Ethyne (C₂H₂)

Why are π-bonds more reactive than σ-bonds?

π-bonds are formed by sideways overlap of p-orbitals and have electron density above and below the plane of the molecule, making them more accessible to attacking reagents.

What are the two main types of organic compounds?

Acyclic (Open-chain) Compounds – Straight or branched-chain structures (e.g., alkanes, alkenes, alkynes).

Cyclic (Closed-chain) Compounds – Carbon atoms form a ring.

• Alicyclic (only carbon in the ring, e.g., cyclohexane).
• Aromatic (contains benzene or related structures, e.g., benzene, toluene).
• Heterocyclic (contains atoms other than carbon in the ring, e.g., furan, thiophene).

What is a functional group?

A functional group is an atom or group of atoms in a molecule responsible for its chemical properties.

Give examples of common functional groups.

-OH (Hydroxyl) → Alcohols

-CHO (Aldehyde) → Aldehydes

>C=O (Carbonyl) → Ketones

-COOH (Carboxyl) → Carboxylic acids

-NH₂ (Amino) → Amines

What is a homologous series?

A homologous series is a group of organic compounds with the same general formula, similar chemical properties, and a difference of CH₂ in molecular formula between consecutive members.

How do you name an organic compound using IUPAC rules?

Identify the longest carbon chain (parent chain).

Number the carbon chain to give lowest numbers to substituents.

Identify and name the functional groups and substituents.

Arrange substituent names alphabetically and use prefixes (di-, tri-, etc., for multiple identical groups).

Give the IUPAC names for:

• CH₃CH₂OH
• CH₃CH₂CH=CH₂
• CH₃COCH₃

• Ethanol
• But-1-ene
• Propan-2-one (Acetone)

What is isomerism?

Isomerism is the phenomenon where compounds have the same molecular formula but different structures or properties.

What are the two main types of isomerism?

What are the types of bond cleavage?

Homolytic Cleavage → Each atom takes one electron (forms radicals).

Heterolytic Cleavage → One atom takes both electrons (forms ions).

What are nucleophiles and electrophiles?

Nucleophiles (electron-rich) → Donate electron pairs (e.g., OH⁻, NH₃, CN⁻).

Electrophiles (electron-deficient) → Accept electron pairs (e.g., H⁺, NO₂⁺, BF₃).

What are the major types of organic reactions?

• Substitution Reactions – One atom/group replaces another (e.g., CH₄ + Cl₂ → CH₃Cl + HCl).
• Addition Reactions – Unsaturated compounds react with small molecules (e.g., C₂H₄ + H₂ → C₂H₆).
• Elimination Reactions – Removal of atoms/groups to form double/triple bonds (e.g., dehydration of alcohols).
• Rearrangement Reactions – Atoms/groups shift within the molecule to form isomers.

What are common purification techniques?

• Sublimation → Used for volatile solids (e.g., camphor).
• Crystallization → Used to purify solids based on solubility.
• Distillation → Used for liquids with different boiling points.
• Fractional Distillation → Separates liquids with close boiling points (e.g., petroleum refining).
• Chromatography → Separates components based on adsorption (used for colored compounds).

What is resonance?

Resonance occurs when a molecule has two or more valid Lewis structures, leading to electron delocalization and stability. Example: Benzene (C₆H₆).

What is the inductive effect?

It is the electron withdrawal or donation through sigma bonds due to electronegativity differences.

What is hyperconjugation?

It is the delocalization of electrons from a C-H bond adjacent to a double bond or carbocation, increasing stability.