Introduction to organic chemistry

Question 1

What does ‘organic’ mean?

Answer 1

Things to do with living beings

Question 2

What is special about Carbon?

Answer 2

Carbon can form rings and very long chains, which may be branched

Question 3

How can carbon form rings and chains?

Answer 3

• It has four electrons in its outer shell, so it forms four covalent bonds
• carbon-carbon bonds are relatively strong and non-polar

Question 4

How strong are carbon-carbon bonds?

Answer 4

347 kJ mol-1

Question 5

What chains form the skeleton of most organic compounds?

Answer 5

Hydrocarbon chains formed by fairly strong carbon-hydrogen bonds

Question 6

How many electrons does carbon have in its outer shell?

Answer 6

8

Question 7

What is the general suffix for compounds with a triple bond?

Answer 7

-yne (e.g. EthYNE)

Question 8

What is the “empirical formula”?

Answer 8

The empirical formula is the simplest ration of the atoms of each element present in a compound

Question 9

What is the molecular formula?

Answer 9

It is the formula that shows the actual number of atoms of each element in the molecule

Question 10

What three factors is the molecular formula found from?

Answer 10

• the empirical formula
• the relative molecular mass of the empirical formula
• the relative molecular mass of the molecule

Question 11

What is the structural formula?

Answer 11

This formula shows the unique arrangement of atoms in a molecule in a simplified form, without showing all the bonds

Question 12

What is the structural formula for ethane?

Answer 12

CH3CH3

Question 13

How are branches in carbon chains shown in the structural formula?

Answer 13

In brackets

Question 14

What is different about the skeletal formulae?

Answer 14

In skeletal notation, carbon atoms are not drawn at all. Straight lines represent carbon-carbon bonds.

Question 15

What is assumed when drawing the skeletal formula of a compound?

Answer 15

Each carbon is assumed to form enough C-H bonds to make a total of 4 bonds

Question 16

What are the bond angles in an unbranched alkane chain?

Answer 16

109.5 degrees

Question 17

What does the “root” of a chain mean?

Answer 17

It tells us the longest unbranched hydrocarbon chain or ring

Question 18

What is the prefix for a side chain with two carbons?

Answer 18

Ethyl (C2H5-)

Question 19

What is different about the prefix of ring molecules?

Answer 19

They have the additional prefix “cyclo”

Question 20

What are functional groups?

Answer 20

Reactive groups attached to hydrocarbon chains

Question 21

What is the general functional group for an alcohol?

Answer 21

R-OH

Question 22

What is a lo and used for?

Answer 22

To tell us the position of any branching in a chain and the position of any functional group

Question 23

What are structural isomers?

Answer 23

They have the same molecular formula but different structures

Question 24

If a chain has more than one functional group, what order do you write the substituting groups?

Answer 24

Alphabetical

Question 25

How do you show that you have more than one of the same substituting group?

Answer 25

By adding prefixes such as di- , tri- , and tetra-

Question 26

What is a homologous series?

Answer 26

It is a family of organic compounds with the same functional group but different carbon chain length

Question 27

Name 5 features of a homologous series:

Answer 27

• they have a general formula (e.g CnH2n+2)
• each member of the series differs from the next by CH2
• the carbon chain length has little effect on the chemical reactivity of the functional group
• the length of the carbon chain affects physical properties like MP and solubility
• chain branching generally reduces melting points because the molecules pack together less well

Question 28

What are isomers?

Answer 28

They are molecules that have the same molecular formula but have a different atom arrangement

Question 29

What three things can structural isomers have?

Answer 29

• the same functional group attached to be main chain at different points (position isomerism)
• functional groups that are different (functional group isomerism)
• a different arrangement of the carbon chain (chain isomerism)

Question 30

What is position isomerism?

Answer 30

Where the functional group is attached to the main chain at different points

Question 31

What is functional group isomerism?

Answer 31

Where there are different functional groups

Question 32

What is chain isomerism?

Answer 32

Where the hydrocarbon chain is arranged differently

Question 33

What does the existence of isomers make difficult?

Answer 33

The identification of an unknown organic compound as there may be a number of compounds with different structures but the same molecular formula

Question 34

What is Stereoisomerism?

Answer 34

Where two (or more) compounds have the same structural formula. They differ in the arrangement of the bonds in space

Question 35

What are the two types of Stereoisomerism?

Answer 35

• E-Z isomerism

* optical isomerism

Question 36

What does E-Z isomerism tell us?

Answer 36

The positions of substituents at either side of a carbon-carbon double bond.

Question 37

What does the ‘Z’ mean in Stereoisomerism?

Answer 37

That the substituents are on the same side of the bond (cis)

Question 38

What does the ‘E’ of E-Z isomerism mean?

Answer 38

That the substituents are on opposite sides of the bond (trans)

Question 39

What can substituted groups joined by a single bond do?

Answer 39

Rotate around the single bond

Question 40

What does the rotation around these single bonds mean?

Answer 40

That there are no isomers

Question 41

What are Z- and E- isomers?

Answer 41

They are separate compounds and are not easily converted from one to another

Question 42

What is life on our planet based on?

Answer 42

Carbon