structural isomers

What are structural isomers?

Compounds that have the same molecular formula but different arrangements of atoms.

How do structural isomers differ from each other?

They differ in the connectivity of atoms

Give an example of two structural isomers with formula C4H10.

Butane and 2-Methylpropane.

What is the molecular formula of all isomers of butane?

C4H10.

Draw or imagine two structures for C4H10 and name them.

CH3CH2CH2CH3 (butane) and CH3CH(CH3)CH3 (2-methylpropane).

How many structural isomers does propane (C3H8) have?

Only one.

How many structural isomers does pentane (C5H12) have?

Three: pentane

Name the straight-chain isomer of C5H12.

Pentane.

Name the branched isomer of C5H12 with one methyl group on carbon 2.

2-Methylbutane.

Name the most branched isomer of C5H12.

2

How many structural isomers does hexane (C6H14) have?

Five.

Name all five isomers of hexane (C6H14).

Hexane; 2-Methylpentane; 3-Methylpentane; 2

What is the molecular formula of all isomers of hexane?

C6H14.

Name the isomer of C6H14 with a methyl group on carbon 2.

2-Methylpentane.

Name the isomer of C6H14 with methyl groups on carbons 2 and 3.

2

What rule determines which chain is the parent chain in IUPAC naming?

Choose the longest continuous chain of carbon atoms.

How do you number the chain when naming an alkane?

Number to give the substituents the lowest possible numbers.

How are substituents named in IUPAC nomenclature?

By using prefixes such as methyl-

How is 2

3-Dimethylbutane different from 2

What is the condensed structural formula for 2-Methylpentane?

CH3CH(CH3)CH2CH2CH3.

What is the condensed structural formula for 2

2-Dimethylpropane?

What is the molecular formula for all alkanes with six carbons?

C6H14.

What general formula represents all alkanes?

CnH2n+2.

Why does the number of isomers increase with chain length?

Because longer chains allow more possible branching patterns.

What type of isomerism is shown by 2-Methylpropane and Butane?

Structural (chain) isomerism.

What type of isomerism is NOT shown by alkanes?

Functional group or position isomerism (since all have single bonds only).

How can you confirm two molecules are isomers?

They have the same molecular formula but different structural formulas.

What does the prefix “iso-” traditionally refer to in alkane names?

A chain with a single methyl branch at the end (e.g.

Which alkane has three structural isomers?

Pentane (C5H12).

Which alkane has five structural isomers?

Hexane (C6H14).

How many isomers does ethane (C2H6) have?

Only one.

How many isomers does methane (CH4) have?

Only one.