3A3 Organic Functional Groups and Compounds

Question 1

Define:

organic molecules

Answer 1

Molecules containing carbon and hydrogen.

Example: Methane (CH₄), the simplest organic compound.

Organic molecules can also contain oxygen, nitrogen, or other elements.

Question 2

What is the basic building block of organic compounds?

Answer 2

Hydrocarbon, or a carbon bound to a hydrogen.

Hydrocarbons form the foundation of more complex organic molecules.

Question 3

How is the base name of an organic compound determined?

Answer 3

Based on the number of carbon atoms in the longest chain.

For example, ‘prop’ for 3 carbons and ‘hex’ for 6 carbons.

Question 4

True or False:

Inorganic molecules lack carbon.

Answer 4

False

Some inorganic compounds, like CO₂, contain carbon.

Question 5

Define:

hydrocarbons

Answer 5

Compounds consisting of carbon atoms bonded only to hydrogen atoms.

Hydrocarbons form the backbone of organic compounds.

Question 6

How are hydrocarbons classified?

Answer 6

Into four categories:

1. Alkanes
2. Alkenes
3. Alkynes
4. Arenes

Each category has distinct structural and chemical properties.

Alkanes contain single bonds, alkenes double bonds, alkynes triple bonds, and arenes an aromatic ring.

Question 7

What are aromatic hydrocarbons?

Answer 7

Hydrocarbons containing carbon atoms in a ring structure with delocalized pi-bond electrons.

Benzene is the most common example.

Question 8

What is the general formula for alkanes?

Answer 8

CₙH₂ₙ₊₂

Where n is the number of carbon atoms.

Question 9

What are the combustion products of alkanes?

Answer 9

• Carbon dioxide
• Water

Complete combustion requires sufficient oxygen.

Question 10

List two uses of alkanes.

Answer 10

1. Fuels
2. Solvents

Methane and propane are common examples.

Methane is the primary component of natural gas.

Question 11

Fill in the Blank:

Alkanes are also known as _______ hydrocarbons.

Answer 11

saturated

In saturated hydrocarbons, every carbon is attached to the maximum number of hydrogen atoms possible.

Alkanes are saturated since they contain only single covalent bonds. Alkenes are alkynes are unsaturated due to presence of double and triple bonds respectively.

Question 12

Which is the simplest alkene?

Answer 12

Ethene

(C₂H₄)

Alkenes contain a carbon-carbon double bond with the general formula; CₙH₂ₙ.

Ethene is commonly known as ethylene.

Question 13

List four types of reactions that alkenes undergo.

Answer 13

1. Addition reactions
2. Elimination reactions
3. Substitution reactions
4. Rearrangement reactions

These reactions are driven by the presence of the pi bond.

Question 14

What is the general formula for alkynes?

Answer 14

CₙH₂ₙ₋₂

Where n is the number of carbon atoms.

Question 15

What types of reactions can alkynes undergo?

Answer 15

Addition reactions

They cannot undergo elimination or rearrangement reactions due to the nature of the triple bond.

Question 16

Which hydrocarbon is used in welding?

Answer 16

Ethyne

(acetylene)

Its high energy release makes it suitable for welding.

Question 17

What are the physical properties of hydrocarbons?

Answer 17

• Low melting points
• Low boiling points
• Insoluble in water
• No conductivity

These properties increase with molecule size.

They are insoluble in water since they are non-polar.

Alkynes have the highest boiling and melting points followed by alkenes.

Question 18

What are the organic factors that affect boiling and melting points?

Answer 18

• Chain branching
• Chain length
• Functional groups
• Double and Triple Bonds

All of these factors must be taken into account, as they can either increase or decrease the boiling and melting points of different compounds.

Question 19

How does chain branching affect the boiling point of hydrocarbons?

Answer 19

Branched hydrocarbons have lower boiling points than straight-chain hydrocarbons.

Branching reduces surface area and intermolecular forces (van der Waals forces).

Question 20

What is a functional group?

Answer 20

A part of organic compounds that contains characteristic qualities that determines the chemical properties of a molecule.

Functional groups are essential for understanding the reactivity and properties of organic compounds.

They are often sites for chemical reactions.

Question 21

List five functional groups.

Answer 21

1. Alkanes
2. Alkenes
3. Alkynes
4. Alcohols
5. Ethers

These groups are crucial for naming and identifying organic compounds.

Other examples include aldehydes, ketones, carboxylic acids, esters, amides, amines, and alkyl halides.

Question 22

What is the general formula for alcohols?

Answer 22

R-OH

Alcohols contain a carbon bound to a hydroxyl (-OH) group.

Alcohols are polar due to the hydroxyl group. These organic compounds are often soluble in water due to their polarity, although their solubility depends on the length of the chain.

Question 23

List three types of alcohols.

Answer 23

1. Primary
2. Secondary
3. Tertiary

The classification depends on the number of carbon atoms bonded to the carbon with the alcohol group.

Question 24

What is an example of a tertiary alcohol?

Answer 24

Tert-butanol

(C(CH₃)₃OH)

Tertiary alcohols are less prone to oxidation than primary or secondary alcohols. The carbon is already bonded to three other carbon atoms as well as a hydroxy group, meaning that there are no free hydrogens for bonding.

Question 25

How does **hydrogen bonding** affect alcohol properties?

Answer 25

Alcohols have **higher boiling** points than alkanes. ## Footnote This also affects their solubility in water.

Question 26

What is the general **formula for carboxylic acids**?

Answer 26

R-COOH ## Footnote Carboxylic acids have both a carbonyl and a hydroxyl group. They are are acidic due to the -COOH group. They are named using the suffix -oic acid.

Question 27

What are the **uses of carboxylic** acids?

Answer 27

* Producing adhesives * Antimicrobial agents * Solvents * Food flavorings ## Footnote Butyric acid, for example, is used for artificial butter flavor.

Question 28

What is the general **formula for ethers**?

Answer 28

R-O-R’ ## Footnote Ethers have an oxygen atom between two alkyl groups. They are more polar than hydrocarbons, but less polar than alcohols.

Question 29

List *three* **uses of ethers**.

Answer 29

1. Solvents in laboratories 1. Anesthetics 1. Fuel additives ## Footnote Their moderate polarity makes them versatile.

Question 30

What distinguishes **ketones** from **aldehydes**?

Answer 30

* Ketones: They contain a **carbonyl group (C=O)** located at the **middle** of the molecule. * Aldehydes: They contain a **carbonyl group** located at the **terminal** carbon. ## Footnote The general formula for ketones is R-CO-R'. The general formula for aldehydes is R-CO-H. Acetone (CH₃COCH₃) is an example of a ketone while formaldeyde (HCHO) is an example of an aldehyde.

Question 31

What is the general **formula for esters**?

Answer 31

R-COOR’ ## Footnote Esters are derived from carboxylic acids where the hydrogen in the OH group is replaced with another R group. The ester group (-COO-) gives esters pleasant fruity odors.

Question 32

How are **esters named**?

Answer 32

The **alkyl group** is named first, followed by the **acid component** with an **-oate ending**. ## Footnote Example: Methyl acetate (CH₃COOCH₃).

Question 33

How does the **ether** group **differ** from the **ester** group?

Answer 33

* Ether has **-O-** group * Ester has **-COO-** group ## Footnote Ethers are more inert compared to esters.

Question 34

What is the general **formula for alkyl halides**?

Answer 34

RX ## Footnote Where R is a carbon chain and X is a halogen. Alkyl halides are also known as haloalkanes. The functional group is a halogen atom (F, Cl, Br, I) bonded to an alkane. Example: Methyl chloride (CH₃Cl).

Question 35

What distinguishes **primary, secondary, and tertiary amines**?

Answer 35

* Primary: **One R group** attached to nitrogen. * Secondary: **Two R groups** attached to nitrogen. * Tertiary: **Three R groups** attached to nitrogen. ## Footnote This classification determines reactivity and boiling points.

Question 36

What is the general **formula for amides**?

Answer 36

R-CONH₂ ## Footnote Amides are derivatives of carboxylic acids.

Question 37

What is a common **use of amides**?

Answer 37

Production of: * Plastics * Pharmaceuticals * Proteins ## Footnote Example: Nylon synthesis.

Question 38

What is the functional group for **phenols**?

Answer 38

An **OH** group attached directly to an **aromatic ring**. ## Footnote Example: Phenol (C₆H₅OH).

Question 39

# Define: arenes

Answer 39

Aromatic hydrocarbons with **alternating double bonds in a ring**. ## Footnote Example: Toluene (C₆H₅CH₃).

Question 40

What is the **role of a phenyl group** in a molecule?

Answer 40

It adds **aromaticity**. ## Footnote Phenyl groups increase stability and delocalization.

Question 41

What is the functional group of **nitriles**?

Answer 41

A carbon triple-bonded to a nitrogen (**C≡N**). ## Footnote Example: Acetonitrile (CH₃CN).

Question 42

What are **thioethers**?

Answer 42

**Sulfur analogs** of ethers. ## Footnote They have the general formula R-S-R’. Example: Dimethyl sulfide (CH₃SCH₃).