Functional Groups: Classification of Organic Compounds (DP IB Chemistry)

The condensed structural formula of propane is CH₃CH₂CH₃.

The skeletal formula of propene is:

False.

The stereochemical formula of 1-chloroethan-1-ol is:

False.

The structural formula of a chemical has all of the chemical bonds displayed, which means that ethanol is:

Functional groups are atoms or groups of atoms that are found in organic compounds and give them their characteristic physical and chemical properties.

True.

Organic compounds with the same functional group belong to the same class.

The functional group of an alkene is the carbon-carbon double bond (C=C).

The functional group for a carboxylic acid is -COOH.

True.

The IUPAC suffix for a ketone is -one.

For an amine:

• Functional group = -NH₂

• IUPAC prefix = amino-

• IUPAC suffix = -amine

Phenyl is the functional group name for aromatic compounds, implying that a benzene ring is present.

For an alcohol:

• Functional group = -OH

• IUPAC prefix = hydroxy-

• IUPAC suffix = -ol

True.

The functional group formula for an ester is R-COO-R.

The carbonyl functional group (C=O) is present in aldehydes and ketones.

True.

The functional group formula for an alkoxy compound is R-O-R.

The suffix for carboxylic acids is -oic acid.

Amides / amido compounds contain the following functional group.

A homologous series is a series or family of organic compounds that have similar features and chemical properties due to having the same functional group.

True.

A functional group is a group of atoms bonded in a specific arrangement that influences the properties of the homologous series

All members of a homologous series have:

• The same general formula

• Same functional group

• Similar chemical properties

• A clear trend in their physical properties

• The difference in the molecular formula between one member and the next is CH₂

The homologous series of alkanes contains only carbon-hydrogen bonds and saturated carbon-carbon bonds.

False.

The alkene functional group is represented by C=C.

The general formula for alkanes is C_nH_2n+2.

The general formula for alkenes is C_nH_2n.

The homologous series of alcohols has the general formula C_nH_2n+1OH.

False.

The general formula of the carboxylic acids is C_nH_2n+1COOH.

The general formula of an aldehyde is C_nH_2n+1CHO.

False.

Each homologous series can be described by a general formula.

False.

As the number of carbons in a straight-chain molecule increases, the boiling point increases.

In a homologous series, boiling point increases with molecular size due to the increased strength of London dispersion forces.

True.

Physical properties such as melting point, density, and viscosity show similar trends to boiling point in a homologous series.

The general formula of halogenoalkanes is C_nH_2n+1X.

True.

Aldehydes and ketones have the same general formula of C_nH_2nO.

False.

The general formula of an alkyne is C_nH_2n-2.

Two homologous series, with general formula, that contain nitrogen include:

• Amines - C_nH_2n+1NH₂

• Amides - C_nH_2n+1NO

The homologous series of esters has the general formula C_nH_2nO₂.

The following compound belongs to the homologous series of ethers.

Homologous series that contain a carbonyl, C=O, bond include:

• Aldehydes

• Ketones

• Carboxylic acids

• Amides

• Esters

The prefix tells you the number of carbon atoms in the longest continuous chain in the hydrocarbon.

There are three carbon atoms in the carbon chain if the prefix is prop-.

The suffix tells you what functional group is on the compound.

The name of CH₃CH₂CH₂CH₂OH is butan-1-ol.

The name of CH₃CH₂CH₂CH₂CH₃ is pentane.

The name of CH₃CH₂COOH is propanoic acid.

The name of CH₃(CH₂)₃HC=CH₂ is hex-1-ene.

False.

The name of CH₃COOCH₂CH₃ is ethyl ethanoate.

The two carbon atoms highlighted (in bold) come from the carboxylic acid used to form the ester.

False.

Numbering in organic compound names sometimes starts from the right to keep the numbers as low as possible.

Certain functional groups such as aldehydes, CHO, and carboxylic acids, COOH, normally have their carbon atom labelled as carbon-1.

The name of the following alcohol is butan-2-ol.

False.

The prefix "eth-" is used for compounds with two carbon atoms.

The prefix "prop-" is used for compounds with three carbon atoms.

An alkyl group is a hydrocarbon side chain, named by adding '-yl' to the normal alkane stem.

Multiple identical side chains are indicated by using prefixes di- (for two), tri- (for three), or tetra- (for four).

True.

In naming alkenes, the carbon atoms are numbered starting with the end closest to the double bond.

Halogenoalkanes are named using:

• The appropriate prefix fluoro-, chloro-, bromo- or iodo-, with a number to identify the carbon it is attached to in the chain

• The appropriate name to identify the longest carbon chain

• The suffix -ane to show that the halogenoalkane is saturated

The following organic compound is 3-hydroxypropanoic acid.

The carboxylic acid carbon is automatically carbon-1, which means the name ends in -oic acid.

The hydroxyl group is attached to carbon-3, which means the name starts with 3-hydroxy.

The chain is 3 carbons long and contains only single bonds, which means the name contains propan.

3-hydroxy + propan + oic acid = 3-hydroxypropanoic acid.

Isomers are compounds that have the same molecular formula but a different arrangement of atoms.

Structural isomers are compounds that have:

• The same molecular formulae

• But different structural formulae.

The three types of structural isomerism are:

1. Functional group isomerism

2. Positional isomerism

3. Branched chain isomerism.

Functional group isomerism is when different functional groups result in the same molecular formula.

True.

Alcohols and ethers can be functional group isomers of each other.

False.

Aldehydes and ketones are functional group isomers of each other.

Positional isomerism is where isomers have the same functional group in different positions on the carbon chain.

True.

Branched chain isomerism is when compounds have the same molecular formula, but their longest hydrocarbon chain is not the same.

A primary alcohol is an alcohol where the carbon atom attached to the -OH group is also attached to only one other carbon atom

False.

In amines, primary, secondary, and tertiary refer to the number of carbon atoms (or alkyl groups) attached to the nitrogen.

The smallest number of carbon atoms required for an alkane to exhibit branched chain isomerism is four.

Cyclic alkanes / cycloalkanes are functional group isomers of alkenes.

Hexan-2-ol, C₆H₁₄O, and ethoxypropane, C₅H₁₂O, are not functional group isomers of each other because they have different molecular formulae.

The positional isomer of propan-2-ol is propan-1-ol:

But-1-ene is a functional group isomer of cyclobutane and a position isomer of but-2-ene.

The branched isomer of butane is methylpropane:

The position isomer of 2-chloromethylpropane is a primary halogenoalkane because the halogen is bonded to a carbon atom that is attached to only one other carbon atom.