3.3.1 Introduction to Organic Chemistry

Question 1

Define General Formula

Answer 1

An algebraic formula that can describe any member of a family of compounds

Question 2

Define Empirical formula

Answer 2

Simplest ratio of atoms of each element in a compound

Question 3

Define Molecular formula

Answer 3

Actual number of atoms of each element in a molecule

Question 4

Define Structural Formula

Answer 4

Shows the atoms carbon by carbon + attached hydrogens & functional groups

Question 5

Define Skeletal Formula

Answer 5

Shows the bonds of the carbon skeleton ONLY + any functional groups

Question 6

Define Displayed Formula

Answer 6

Shows how all the atoms are arranged and all the bonds between them

Question 7

What is the functional group for alkanes?

Answer 7

C—C

Question 8

What is the functional group for alkenes?

Answer 8

C=C

Question 9

What is the functional group for haloalkanes?

Answer 9

C—halogen

Question 10

What is suffix for alkenes?

Answer 10

-ene

Question 11

What is the prefix for haloalkanes? (4x)

Answer 11

• fluoro-
• chloro-
• bromo-
• iodo-

Question 12

What is the general formula for alkanes?

Answer 12

C_nH_2n+2

(n = 1,2,3 etc.)

Question 13

What is the general formula for alkenes?

Answer 13

C_nH_2n

(n = 1,2,3 etc.)

Question 14

What is the general formula for haloalkanes?

Answer 14

C_nH_2n+1X

(n = 1,2,3 etc.)

(X = F, Cl etc.)

Question 15

Name 5 features of a homologous series

Answer 15

1. Chemically similar / react in same way
2. Each successive member differs by CH₂
3. Same general formula
4. Same functional group
5. Gradation in physical properties or specified trend

Question 16

What effect does the length of the carbon chain have on chemical reactivity of the functional group?

Answer 16

Has little effect

Question 17

What affects the physical properties (e.g. melting/boiling point & solubility) of carbon molecule?

Answer 17

The length of carbon chain

Question 18

In general: small molecules are ___ and larger ones are ____ + _____

Answer 18

gas & liquids + solids

Question 19

Why does the length of the carbon chain affect physical properties?

Answer 19

Melting/boiling points increase by small amounts as no. of C in chain increases ∵ intermolecular forces increase

Question 20

How does chain branching generally affect melting points and why?

Answer 20

• Reduces melting points
• ∵ less surface area (molecules pack together less well) & weaker van der Waals forces

Question 21

Hydrogen ring molecules have prefix of ____

Answer 21

‘cyclo’

Question 22

What are isomers?

Answer 22

Molecules that have the same molecular formula but their atoms are arranged differently

Question 23

Name 2 type of isomers

Answer 23

Stereoisomers & structural isomers

Question 24

What are structural isomers?

Answer 24

Have same molecular formula but different structural formulas

Question 25

Name 3 types of structural isomers

Answer 25

• Chain Isomers
• Positional Isomers
• Functional Group Isomers

Question 26

What is a chain isomer?

Answer 26

• Same molecular formula
• Hydrocarbon chain is arranged differently

Question 27

What is a positional isomer?

Answer 27

• Compounds with same molecular formula
• But different structures due to different positions of the same functional group on
• The same carbon chain

Question 28

What are functional group isomers?

Answer 28

• Same molecular formula
• Have the same atoms but have different functional groups

Question 29

What are stereoisomers?

Answer 29

(Where 2 or more) compounds with the same structural formula but with atoms arranged differently in space

Question 30

_____ show E/Z Isomerism

Answer 30

Alkenes

Question 31

The atoms connected to the C=C double bonds _____ rotate around them like they can around single bonds

Answer 31

Cannot

Question 32

What causes the type of stereoisomerism called E/Z isomerism?

Answer 32

Restricted rotation around the (planar) C=C double bond

Question 33

Explain how alkenes show E/Z isomerism

Answer 33

1. Alkenes have restricted rotation around their C=C double bonds
2. & if both of the double-bond carbons have different functional groups attached to them = get 2 stereoisomers (E/Z isomerism)

Question 34

Where are the same groups situated in (cis) Z-isomer?

Answer 34

Either both above or both below double bond

(matching groups are on ‘ze zame zide’)

Question 35

Where are the same groups situated in (trans) E-isomer?

Answer 35

Same groups positioned across the double bond

(matching groups are ‘enemies’)

Question 36

What rules do we use to identify whether a molcule with a C=C bond, surrounded by 3 or 4 different functional groups, is a E- or Z- isomer?

Answer 36

Use the Cahn-Ingold-Prelog (CIP) priority rules

Question 37

Describe how we use the CIP rules to identify a E-/Z-isomer

Answer 37

1. Identify the groups directly bonded to each of the C=C carbon atoms
2. Assign a priority by finding the atom with the highest atomic number - this given the highest priority
3. If higher priority groups = same side of molecule = Z-isomer OR if higher priority groups = different sides of molecule = E-isomer

Question 38

CIP rules: What do you do if the atoms directly bonded to carbon are the same?

Answer 38

Look at next atom in the groups to work out which has the higher priority

Question 39

Why is the IUPAC system used for naming organic compounds?

Answer 39

It’s the agreed international language of chemistry so it allows scientific ideas to be communicated across the globe more effectively

Question 40

State the name of CH₃CH=CHCH₂OH

Answer 40

But-2-en-1-ol