Organic 1 Section 3 - Unit 11: Introduction to Organic Chemistry

Question 1

Define empirical formula

Answer 1

Simplest whole number ratio of atoms in a molecule

Question 2

Define molecular formula

Answer 2

Actual ratio of the number of atoms in a molecule

Question 3

Define displayed formula

Answer 3

Shows every atom and every bond in a molecule

Question 4

Define structural formula

Answer 4

Shows arrangement of atoms in a molecule without showing every bond

Question 5

Define structural isomer

Answer 5

Compounds with the same molecular formula but different structural formula

Question 6

Define positional isomer

Answer 6

Compounds where the functional group is attached to the main chain at a different place

Question 7

What is functional group isomerism

Answer 7

Same atoms but a different functional group due to a different arrangement of atoms

Question 8

What is chain isomerism

Answer 8

Hydrocarbon chain is organised differently

Question 9

Define stereoisomerism

Answer 9

When molecules have the same structural and molecular formula, but have a different arrangement of atoms in space

Question 10

What is E-Z isomerism and how are the E and Z isomers decided?

Answer 10

• E-Z isomerism is caused by the limited rotation about C=C double bonds
• If the two substituents with the highest molecular mass are on the same side of the double bond, it is the Z isomer
• If they are on different sides, it is the E isomer

Question 11

State two general features of an homologous series of compounds (2 marks)

Answer 11

• Same functional group

- Same general formula

Question 12

How is the unpaired electron in a radical represented?

Answer 12

By a dot before or after the molecule

Question 13

Define homolytic fission

Answer 13

• The breakage of a bond to form 2 free radicals

- Each atom gets one electron from the covalent bond

Question 14

Define free radical

Answer 14

A reactive species which possess an unpaired electron

Question 15

Define heterolytic fission

Answer 15

• The breakage of a bond to form ions

- One atom gets both electrons from the covalent bond

Question 16

How is the formation of a covalent bond shown?

Answer 16

By a curly arrow that starts from a lone electron pair or from another covalent bond

Question 17

How is the breakage of a covalent bond shown?

Answer 17

By a curly arrow starting from the bond

Question 18

When do E-Z stereoisomers form? (2)

Answer 18

• When there is restricted rotation around the C=C double bond.
• When there are two different groups attached both ends of the double bond

Question 19

Explain the CIP rules used to determine the name of an alkene

Answer 19

• Compare the atomic number of the atoms directly attached to each side of the double bond
• The atom of higher atomic number is given priority