Alkenes: Structure, Nomenclature, and Stability in Organic Chemistry

What forms the pi bond in ethylene?

The overlap of the unhybridized p orbitals of sp2 hybrid carbon atoms.

What is required to break a pi bond?

Energy.

What is a saturated hydrocarbon?

A hydrocarbon where all carbons are bonded to as many hydrogens as possible.

What is the general formula for alkenes?

CnH2n.

What does each pi bond or ring represent in terms of hydrogen deficiency?

One element of unsaturation.

How many elements of unsaturation does a triple bond count as?

Two elements of unsaturation.

What is the first step in IUPAC nomenclature for alkenes?

Find the longest continuous carbon chain that includes the double-bonded carbons.

What suffix is used for alkenes in IUPAC nomenclature?

-ene.

What is the rule for numbering the carbon chain in alkenes?

Number the chain so that the double bond has the lowest possible number.

What is the stability condition for trans cycloalkenes?

Trans cycloalkenes are not stable unless the ring has at least eight carbons.

What does E-Z nomenclature help identify?

Geometric isomers that cannot be labeled cis or trans due to having more than 2 substituents on the pi bond.

What indicates a Z isomer in E-Z nomenclature?

High-priority groups are on the same side of the pi bond.

What indicates an E isomer in E-Z nomenclature?

High-priority groups are on opposite sides of the pi bond.

How does polarity affect the boiling points of alkenes?

Higher polarity increases the boiling point.

What is the relationship between molecular mass and boiling points of alkenes?

Boiling points increase with molecular mass.

What is the heat of hydrogenation in relation to alkene stability?

The more substituted the double bond, the lower its enthalpy of hydrogenation, indicating more stability.

What does the degree of substitution in alkenes refer to?

The number of alkyl groups attached to the C=C double bond.

What is Bredt's Rule?

A bridgehead carbon in a bridged bicyclic compound cannot have a double bond unless one of the rings contains eight carbon atoms or more.

What is the stability condition for small cycloalkenes?

The cis isomer is more stable than the trans isomer.

What is a bicyclic compound?

A compound containing two rings in its structure.

What are bridgehead carbons?

The carbon atoms where the two rings meet.

What is a fused bicyclic compound?

One where a single bond joins the two bridgehead carbons.

What is a bridged bicyclic compound?

One where at least one of the bridges contains one or more carbon atoms.

What happens to the stability of trans double bonds in rings larger than eight carbons?

The trans double bond is almost as stable as the cis double bond.

What is the effect of ring strain on alkene stability?

Ring strain can affect the stability of an alkene, especially in small rings.

What is the boiling point trend for alkenes with branching?

Branching lowers the boiling point.

What is the relationship between heat of hydrogenation and alkene stability?

Lower heat of hydrogenation indicates more stable alkenes.