11.0 Introduction to organic chemistry

Question 1

What is an empirical formula and how is it calculated?

Answer 1

Simplest ratio of elements in a compound. Divide the experimental element values by Ar, then find the simplest ratio.

Question 2

What is a molecular formula?

Answer 2

The number and symbol of each element in a molecule.

Question 3

What is a general formula?

Answer 3

The numerical relationship between each element in a compound. Used to identify homologous series.

Question 4

What is a structural formula?

Answer 4

The number and symbol of each element bonded to the sequence of carbon atoms in an organic molecule.

Question 5

What is a displayed formula?

Answer 5

The symbol of each atom with lines to show how they are covalently bonded to each other.

Question 6

What is a skeletal formula?

Answer 6

Use of connected lines to show the position of carbon atoms in a molecule, plus any other elements that are not hydrogen. Hydrogen atom positions are assumed.

Question 7

What are the characteristics of a homologous series?

Answer 7

1. Same general formula
2. Same functional group
3. Differ by CH2
4. Similar trend in physical properties

Question 8

Give the root names for organic molecules containing one to six carbon atoms

Answer 8

Meth, eth, prop, but, pent, hex

Question 9

Give the main stages in IUPAC naming of organic molecules

Answer 9

1. Name the root (longest unbranched chain)
2. Identify and name any functional groups or side chains.
3. Place the names as prefix/suffix in alphabetical order.
4. Add locant numbers to give the lowest possible
   combination of values.

Question 10

What is a structural isomer?

Answer 10

Same molecular formula but different structural formula

Question 11

What are the three types of structural formula?

Answer 11

1. Chain isomer (change arrangement of carbon atoms)
2. Positional isomer (change position of functional group)
3. Functional group isomer (change arrangement of atoms in functional group to give a different functional group)

Question 12

What is a stereoisomer?

Answer 12

Same structural formula but different 3D arrangement of bonds in space

Question 13

What are E/Z isomers?

Answer 13

Where priority groups are fixed in position either on the same plane (Z) or opposite planes of the molecule (E).

Question 14

Why do E/Z isomers exist?

Answer 14

C=C bonds are non-rotating, so if each C has differing groups bonded to it, the largest ‘priority’ group affects the E/Z naming. CIP Priority rules.