3.3.1 Intro to organic chemistry for A-Level Chemistry (AQA)

What is the simplest whole-number ratio of atoms of each element in a compound called?

Empirical formula

It shows the simplest ratio of atoms present.

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What formula shows the actual number of atoms of each element in a molecule?

Molecular formula

For example, glucose has molecular formula C₆H₁₂O₆.

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Fill in the blank:

A formula showing the arrangement of atoms and bonds in a molecule is called the _______ formula.

structural

It indicates how atoms are connected.

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True or False:

A displayed formula shows every atom and bond in a molecule.

True

All covalent bonds are shown explicitly.

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What type of formula uses lines to represent carbon–carbon bonds and omits most hydrogen atoms?

Skeletal formula

Carbon atoms are implied at the ends and intersections of lines.

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True or False:

Skeletal formulas normally show all hydrogen atoms attached to carbon.

False

Hydrogens attached to carbon are usually omitted.

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Fill in the blank:

A family of organic compounds with the same functional group is called a _______ series.

homologous

Members differ by a repeating –CH₂– unit.

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What feature is common to all members of a homologous series?

Same functional group

This leads to similar chemical reactions.

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True or False:

Members of a homologous series show a gradual change in physical properties.

True

For example, boiling point increases with chain length.

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What naming system is used internationally for naming organic compounds?

IUPAC nomenclature

The International Union of Pure and Applied Chemistry sets the rules.

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Fill in the blank:

In IUPAC naming, the longest continuous chain of carbon atoms determines the _______ name.

parent

The parent chain forms the base name of the compound.

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According to A-level requirements, organic compounds should be named using chains of up to how many carbon atoms?

Six

Students must apply IUPAC rules to chains and rings up to six carbons.

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What term describes the step-by-step pathway showing how reactants form products in an organic reaction?

Reaction mechanism

It shows the movement of electrons and formation/breaking of bonds.

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What type of species has an unpaired electron and is involved in certain organic reactions?

Radical

Radicals are highly reactive species with a single unpaired electron.

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Fill in the blank:

In radical mechanisms, the unpaired electron is represented by a _______.

dot

A dot next to the atom symbol shows the radical.

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True or False:

Curly arrows are normally used to show electron movement in free-radical mechanisms.

False

Radical mechanisms usually use single dots rather than curly arrows.

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What type of arrow is used to show the movement of an electron pair in many organic mechanisms?

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Curly arrow

The arrow starts at the electron pair and points to where the electrons move.

True or False:

A curly arrow can start from a lone pair of electrons to show bond formation.

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True

This represents donation of an electron pair to form a covalent bond.

Fill in the blank:

When a covalent bond breaks in a mechanism, the curly arrow starts from the _______.

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bond

This indicates the electrons move away from that bond.

What does a curly arrow represent in an organic reaction mechanism?

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Movement of an electron pair

It shows how electrons rearrange during the reaction.

True or False:

Reaction mechanisms must show the structures of all species involved in each step.

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True

Each intermediate and transition step should be represented.

What must be written for each step in a free-radical mechanism besides structures?

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Balanced equation

Each stage (initiation, propagation, termination) must balance atoms.

Fill in the blank:

The formation of a new covalent bond occurs when an electron _______ is shared between atoms.

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pair

Curly arrows illustrate this movement of electron pairs.

Why are mechanisms useful in organic chemistry?

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Explains how reactions occur.

They show the detailed sequence of bond breaking and bond forming.

What term describes **compounds with the same molecular formula** but different **structural arrangements**?

Isomers ## Footnote Isomers share a formula but differ in structure or spatial arrangement.

What type of **isomerism** occurs when **atoms are connected in different ways** within molecules?

Structural isomerism ## Footnote These isomers differ in the arrangement of atoms in the molecule.

# Fill in the blank: **Structural isomers** have the same molecular formula but different _\_\_\_\_\_\_ formulas.

structural ## Footnote The atoms are connected differently.

# True or False: **Chain isomerism** occurs when the **carbon skeleton differs** between molecules.

True ## Footnote For example, straight-chain vs branched-chain hydrocarbons.

What type of **structural isomerism** occurs when the **functional group** is located in different positions?

Position isomerism ## Footnote The carbon skeleton remains the same but the group moves position.

# True or False: **Functional group isomers** have the same functional group but in different positions.

False ## Footnote Functional group isomers contain different functional groups.

# Fill in the blank: Isomers that differ only in the **spatial arrangement of atoms** are called _\_\_\_\_\_\_ isomers.

stereoisomers ## Footnote The bonding arrangement remains the same.

What type of **stereoisomerism** occurs due to **restricted rotation around a C=C double bond**?

E–Z isomerism ## Footnote The double bond prevents free rotation of substituents.

# True or False: **E–Z isomerism** can occur around **single carbon–carbon bonds**.

False ## Footnote Single bonds rotate freely so stereoisomerism does not occur.

# Fill in the blank: The system used to assign **priorities** when determining E or Z configuration is the _\_\_\_\_\_\_ rules.

CIP ## Footnote Cahn–Ingold–Prelog priority rules determine substituent ranking.

In **E–Z notation**, what does the letter **E** indicate about the highest priority groups?

Opposite sides ## Footnote E comes from the German “entgegen,” meaning opposite.

In **E–Z notation**, what does the letter **Z** indicate about the highest priority groups?

Same side ## Footnote Z comes from the German “zusammen,” meaning together.

What is the functional group isomer of an **aldehyde**?

A ketone

What is the functional group isomer of a **ketone**?

An aldehyde

What is the functional group isomer of an **alcohol**?

An ether

What is the functional group isomer of an **ether**?

An alcohol

What is the functional group isomer of a **carboxylic acid**?

An ester

What is the functional group isomer of an **ester**?

A carboxylic acid

3.3.1 Intro to organic chemistry Flashcards

Apply systematic nomenclature and structural representations to classify organic compounds and reaction mechanisms. (42 cards)