Organic Chemistry

A comprehensive set of 300 question-and-answer flashcards covering key concepts, definitions, mechanisms, and examples from Module 1 Organic Chemistry lecture notes.

What essential element must organic compounds contain?

Carbon

Which carbon-containing compounds are generally excluded from organic chemistry?

Carbon dioxide and carbonates (CO3^2–)

What does the suffix “-ol” signify in an organic compound’s name?

Presence of a hydroxyl functional group

How many valence electrons does carbon have?

Four

How many valence electrons does nitrogen have?

Five

How many valence electrons does oxygen possess?

Six

How many valence electrons are found in halogens (F, Cl, Br, I)?

Seven

How many valence electrons does hydrogen have?

One

According to the octet rule, how many bonds does carbon typically form?

Four

How many bonds does nitrogen usually need for an octet?

Three

How many bonds does oxygen usually form for an octet?

Two

How many bonds do halogens generally form?

One

Why is hydrogen excused from the octet rule?

Its first shell requires only two electrons for stability

Which structural formula shows every atom and bond explicitly?

Expanded / Lewis / Kekulé (line-bond) formula

Which structural formula omits most single bonds for brevity?

Condensed or abbreviated formula

In skeletal formulas, what is implied at each vertex?

A carbon atom

In skeletal formulas, which hydrogens are usually drawn in?

Hydrogens attached to heteroatoms (O, N, etc.)

Name the three main carbon-skeleton frameworks.

Linear, branched, cyclic

What is a ring containing only carbon atoms called?

Carbocyclic ring

What term denotes a ring containing heteroatoms?

Heterocyclic ring

What does “saturated” mean in reference to carbon–carbon bonds?

All C–C bonds are single

What term describes a system of alternating single and double bonds?

Conjugated

When adjacent double bonds share no single bond between them, the system is _.

Cumulated

Two C=C bonds separated by two or more single bonds are called _ double bonds.

Isolated

Which body establishes the rules for systematic organic nomenclature?

IUPAC (International Union of Pure and Applied Chemistry)

In IUPAC naming, what is the “parent”?

Usually the longest continuous carbon chain

Which infix denotes only single bonds in a hydrocarbon chain?

“-an-”

Which infix indicates one or more double bonds?

“-en-”

Which infix signals the presence of a triple bond?

“-yn-”

What prefix is used for a one-carbon chain?

Meth-

What prefix designates a two-carbon chain?

Eth-

What prefix corresponds to three carbons?

Prop-

What prefix corresponds to four carbons?

But-

What prefix corresponds to five carbons?

Pent-

What two electronic conditions are required for a covalent bond to form?

Two unpaired electrons in overlapping orbitals

Sigma bonds arise from what type of orbital overlap?

Head-on (axial) overlap

Pi bonds arise from what type of orbital overlap?

Sideways overlap of p orbitals

Which is generally stronger, a sigma bond or a pi bond?

Sigma bond

Which bond between two atoms always forms first?

Sigma bond

Pi bonds result from overlap of which orbitals only?

p orbitals

How many sigma bonds does an sp3-hybridized carbon form?

Four sigma bonds

What is the molecular geometry of an sp3 center?

Tetrahedral

What ideal bond angle is associated with sp3 hybridization?

Approximately 109.5°

How many total substituents surround an sp3 atom?

Four

How many sigma and pi bonds are associated with an sp2 carbon?

Three sigma and one pi bond

What geometry corresponds to sp2 hybridization?

Trigonal planar

What bond angle is typical of an sp2 center?

About 120°

In sp2 hybridization, how many unhybridized p orbitals remain?

One

How many sigma bonds can an sp-hybridized atom form?

Two

What is the geometry of an sp-hybridized center?

Linear

What bond angle characterizes sp hybridization?

180°

How many unhybridized p orbitals remain on an sp center?

Two

Shortcut: a carbon with four single bonds is usually _ hybridized.

sp3

Shortcut: a carbon in one C=C double bond is _ hybridized.

sp2

Shortcut: a carbon in a C≡C triple bond is _ hybridized.

sp

Do intermolecular forces act within or between molecules?

Between molecules

Name five common types of intermolecular forces.

London dispersion, dipole-dipole, hydrogen bonding, ion-dipole, ion-ion

Which intermolecular force is present in all molecules?

London dispersion forces

Dipole-dipole forces occur between molecules that are _.

Polar (possess permanent dipoles)

Hydrogen bonding requires hydrogen attached to which three electronegative atoms?

Fluorine, oxygen, or nitrogen

Among dispersion, dipole-dipole, and hydrogen bonds, which is strongest?

Hydrogen bonding

Increasing molecular polarity generally _ intermolecular attractions.

Strengthens

Hydrocarbons are generally _ with respect to polarity.

Nonpolar

Adding electronegative atoms to a hydrocarbon chain _ its polarity.

Increases

What rule summarizes solubility behavior by polarity?

Like dissolves like

How does increasing carbon chain length affect water solubility?

It decreases solubility

How does branching influence water solubility?

Branching usually increases solubility

London dispersion forces become stronger with greater molecular _.

Surface area (or molar mass)

Linear molecules exhibit _ dispersion forces than highly branched ones.

Stronger

As intermolecular forces get stronger, boiling point generally _.

Increases

For alkanes of equal carbon number, more branching leads to _ boiling points.

Lower

Which has the higher boiling point: hexane or pentane?

Hexane

Relationship between molecular strain and stability: more strain equals _ stability.

Lower

List three types of molecular strain.

Angle strain, steric strain, torsional strain

Which common cycloalkane is essentially strain-free?

Cyclohexane

Cyclopropane’s high strain energy is due mainly to what kind of strain?

Angle strain

Electron delocalization tends to _ molecular stability.

Increase

Two requirements for electron delocalization are an electron source and an adjacent _ carbon.

sp2

Electron-withdrawing groups exert what inductive effect?

They pull electron density (electron-withdrawing IE)

Electron-donating groups push electrons via the _ effect.

Inductive (electron-donating IE)

Electron-withdrawing groups generally _ acidity.

Increase

Electron-donating groups generally _ basicity.

Increase

Define constitutional isomers.

Compounds with the same molecular formula but different connectivity

Name the three subclasses of constitutional isomers.

Chain (skeletal), positional, functional

Define stereoisomers.

Compounds with identical connectivity but different spatial arrangement

Difference between conformational and configurational isomers?

Conformers interconvert by rotation; configurational need bond breaking

Two major categories of configurational isomers are and .

Geometric (cis/trans, E/Z) and optical (enantiomers, diastereomers)

In cyclohexane, bonds parallel to the ring axis are called _ bonds.

Axial

Bonds roughly around the ring equator are called _ bonds.

Equatorial

Which conformation of ethane is most stable?

Anti (staggered anti)

Rank ethane conformations by stability.

Anti > gauche > eclipsed > fully eclipsed (syn)

Geometric isomerism arises from restricted rotation in or .

Double bonds or rings

The term “cis” indicates substituents on the _ side.

Same

“Trans” indicates substituents on _ sides.

Opposite

Cis/trans labels apply only when each sp2 carbon bears how many substituents?

Exactly one substituent (besides H)

When double-bond carbons bear more than one substituent, which notation is used?

E/Z notation

What rules assign E or Z configuration?

Cahn-Ingold-Prelog (CIP) rules

CIP priority is based primarily on _ number.

Atomic

For priority, a double bond counts as the attached atom appearing _.

Twice

A carbon attached by a triple bond is counted how many times in CIP?

Three times