3.3.1 Introduction to organic chemistry

Question 1

Define structural isomerism.

Answer 1

• Same molecular formula but different structures
• Chain isomerism (pentane, 2-methylbutane, 2,2,-dimethylpropane)
• Position isomerism (1-bromopropane, 2-bromopropane)
• Functional group isomerism (ethanol, hexene same MF but atoms arranged to give diff func. groups)

Question 2

Define stereoisomerism.

Answer 2

• Same structural formula but different spatial arrangement of atoms
• Alkenes = E-Z isomerism.

Question 3

How do E-Z isomerism arise?

Answer 3

• restricted rotation around the C=C
• 2 different groupsattached at both ends of double bond.

Question 4

How do you name e-z isomerism?

Answer 4

• determine the priority group on both sides of double bond.
• Priority group = atom with the bigger atomic n.o.

Question 5

What is Cahn-Ingold-Prelog priority rules?

Answer 5

1. Compare atomic number of atoms directly attached to each side of double bond. Highest atomic number = priority.
2. If atoms are the same, consider atoms at distance 2 from double bond.

Question 6

What is the molecular formula?

Answer 6

• The formula which shows the actual number of each type of atom

Question 8

What is the empirical formula?

Answer 8

shows the simplest whole number ratio of atoms of each element in the compound

Question 9

What is general formula?

Answer 9

algebraic formula for a homologous series e.g. CnH2n

Question 10

What is structural formula?

Answer 10

shows the minimal detail that shows the arrangement of atoms in a molecule without shwoing bonds, eg for butane: CH3CH2CH2CH3

Question 11

What is displayed formula?

Answer 11

• show all the covalent bonds and atoms present in a molecule i.e.
  —H H
  H-C-C-H
  —H H