Organic chemsitry

Question 1

Define electronegativity

Answer 1

A chemical property which describes the tendency of an atom to attract a shared pair of electrons towards itself

Question 2

What is the electronegativity of carbon?

Answer 2

Low, so it will share its electrons

Question 3

What are the two main categories of carbon compounds?

Answer 3

• aliphatic (either alicyclic or acyclic)

- aromatic

Question 4

Describe the difference between aliphatic and aromatic molecules?

Answer 4

• aromatic are always unsaturated whereas aliphatic can be saturated or unsaturated.
• aromatic are always cyclic whereas aliphatic can be linear aswell
• aromatic need special conditions to react whereas aliphatic can react more freely and easily

Question 5

Define a heteroatom

Answer 5

Any atom not hydrogen or carbon

Question 6

What is a homologous series?

Answer 6

A group of organic compounds with similar structural formulae and similar properties but whose formulae differ by a constant component

Question 7

What happens to energy when bonds are formed?

Answer 7

Energy is released and the system becomes more stable

Question 8

Name the first 4 alkanes

Answer 8

methane (CH4)
ethane (C2H6)
propane (C3H8)
butane (C4H10)

Question 9

What are isomers?

Answer 9

A compounds with the same molecular formula, but different molecular structures

Question 10

What are the rules in naming alkanes?

Answer 10

1. identify longest carbon chain
2. identify branches on this chain, name them according to no. c atoms they contain e.g. methyl, ethyl
3. number the carbon atoms on longest chain to describe the positions of the branches
4. write branches in alphabetical order

Question 11

What is the formula for alkanes?

Answer 11

CnH2n+n

Question 12

What is the formula for alkenes?

Answer 12

CnH2n

Question 13

What is the formula for alkynes?

Answer 13

CnH2n-2

Question 14

Describe the difference in bonds between alkanes, alkenes and alkynes

Answer 14

alkanes= all carbon double bonds are single bonds
alkenes = at least 2 carbon atoms are joined by a double bond
alkynes = at least 2 carbon atoms are joined by a triple bond

Question 15

Name some common functional groups

Answer 15

alcohol, alkene, alkane, alkyne carboxylic acid, ester,

Question 16

Describe the reactivity difference between alkanes and alkenes?

Answer 16

Alkanes are not very reactive but alkenes are very reactive due to double bond

Question 17

What is hybridisation?

Answer 17

the mixing of atomic orbitals into new hybrid orbitals

Question 18

How are atomics formed?

Answer 18

From sp2 (1 s orbital and 2p orbitals) hybrised carbon atoms joined in a 6 membered ring e.g. benzene C6H6

Question 19

What is the orbital structure of carbon?

Answer 19

1s2,2s2,2p1,2p1

Question 20

Name the two ways in which atoms can be arrange differently in a compound

Answer 20

trans, opposite orientations, across

Cis = same spatial orientations, on the same side

Question 21

What is stereo isomerism?

Answer 21

all atoms in the compounds are attached to the same partners, but the partners are arranged differently in space

Question 22

What is geometric isomerism?

Answer 22

the isomerism shown by some alkenes because there is no free rotation about the double bond

Question 23

What is optical isomerism?

Answer 23

organic molecules can exist in two forms that are mirror images of one another- they are super imposed

Question 24

What is the ‘chiral centre’ in terms of optical isomerism?

Answer 24

The carbon atom where it is bonded to four different atoms or groups

Question 25

What are the ‘enantiomers’ in terms of optical isomerism?

Answer 25

The mirror images

Question 26

name 4 chemical reactions of alkenes

Answer 26

• combustion
• addition
• oxidation
• polymerisation

Question 27

Describe polymerisation

Answer 27

Where many monomers join together in multiple addition reactions to make a polymer

Question 28

Name 3 different types of polymer

Answer 28

• block copolymer ( contains blocks of monomers the same type)
• graft copolymer (contains a main chain polymer of other monomers)
• random copolymer (contains a random arrangement of the multiple monomer)

Question 29

What are biopolymers?

Answer 29

Polymers are produced by living organisms aka polymeric biomolecules

Question 30

Name 3 properties of synthetic polymers

Answer 30

• resistant to chemicals
• can be both thermal and electrical insulators
• light in weight

Question 31

What is valence?

Answer 31

• The number of electrons available for bonding

Question 32

Name two nucleic acids

Answer 32

DNA and RNA

Question 33

What are nucleic acids made up of?

Answer 33

nucleotides

Question 34

Name the 4 main types of macromolecules

Answer 34

• carbohydrates
• lipids
• proteins
• nucleic acids

Question 35

What are carbohydrates made up of?

Answer 35

carbon, hydrogen and oxygen

Question 36

Name 4 functions of carbohydrates

Answer 36

• energy storage (starch and glycogen)
• energy transport
• structure (cellulose and chitin)
• molecular recognitions

Question 37

Name 3 functions of lipids

Answer 37

energy storage = triglycerides
Membrane structure = phospholipids
signalling molecules = steroidal hormones

Question 38

What 2 properties does fatty acid saturation affect in triglycerides?

Answer 38

fluidity and metabolism

Question 39

What 4 things can cause denaturation?

Answer 39

• heat
• detergents
• ionic conditions
• pH

Question 40

What determines and stabilizes protein tertiary structure? (4)

Answer 40

• amino acid sequence
• bonding
• hydrophobic exclusion
• chaperon proteins

Question 41

What is an arene?

Answer 41

A hydrocarbon that contains both aromatic and aliphatic groups