AS Organic Chemistry Key Terms and Processes

Question 1

Why does carbon form a large number of compounds?

Answer 1

• Each carbon atom can form four covalent bonds to other atoms
• They can be either single, double or triple bonds
• Carbon atoms can also bond to other carbon atoms forming long carbon chains

Question 2

Define the term ‘hydrocarbon’

Answer 2

A hydrocarbon is a compound containing hydrogen and carbon atoms only

Question 3

Define the term ‘saturated hydroacrbon’

Answer 3

A saturated hydrocarbon has single bonds only

Question 4

Define the term ‘unsaturated hydrocarbon’

Answer 4

An unsaturated hydrocarbon contains carbon to carbon multiple bonds

Question 5

Define the term ‘Homologous series’

Answer 5

A family of hydrocarbons with similar chemical properties who share the same general formula and have the same functional group and each successive member differs by CH2

Question 6

Define the term ‘functional group’

Answer 6

The part of the organic compound that is largely responsible for the molecule’s chemical properties

Question 7

Define the term ‘aliphatic’

Answer 7

Carbon atoms are joined in un-branched or branched chains, or non-aromatic rings

Question 8

Define the term ‘alicyclic’

Answer 8

Carbon atoms are joined to each other in ring structures, with or without branches

Question 9

Define the term ‘aromatic’

Answer 9

Some or all the Carbon atoms are found in a benzene ring

Question 10

Define the term ‘alkanes’

Answer 10

Containing C-C bonds

Question 11

Define the term ‘alkenes’

Answer 11

Containing C=C bonds

Question 12

Define the term ‘alkynes’

Answer 12

Containing at least one triple C to C bond

Question 13

Define the term ‘empirical formula’

Answer 13

Simplest whole number ratio of the atoms of each element present in a compound

Question 14

Define the term ‘molecular formula’

Answer 14

The number and type of atoms of each element present in a molecule

Question 15

Define the term ‘general formula’

Answer 15

the simplest algebraic formula for any member of a homologous series

Question 16

Define the term ‘displayed formula’

Answer 16

Shows the relative positioning of all the atoms in a molecule and the bonds between them

Question 17

Define the term ‘structural formula’

Answer 17

Uses the smallest amount of detail necessary to show the arrangement pf atoms in a molecule

Question 18

Define the term ‘skeletal formula’

Answer 18

a simplified organic formula that removes:
- all the the carbon and hydrogen labels from carbon chains
- any bonds to hydrogen
And leaves just a carbon skeleton and any functional groups

Question 19

Define the term ‘structural isomerism’

Answer 19

Compounds with the same molecular formula nut different structural formulae

Question 20

Covalent bond

Answer 20

A shared pair of electrons between two atoms

Question 21

Homolytic Bond Fission

Answer 21

When a covalent bond is broken, each of the bonded atoms takes one of the shared pair of electrons from the bond, each atom has a single unpaired electron called a radical

Question 22

Heterolytic Bond Fission

Answer 22

When a covalent bond beaks, one of the bonded atoms takes both bonded electrons; the atom that tales both electrons becomes an anion, and the other becomes a cation

Question 23

What do ‘curly arrows’ in reaction mechanisms represent?

Answer 23

Used to show the movement of electron pairs when bonds are broken/made

Question 24

Bonding in alkanes

Answer 24

• Each carbon atom is joined to four other atoms by single covalent bonds, sigma bonds, as a result of the direct overlap of two orbitals

Question 25

Shape of alkanes

Answer 25

Each C12 atom is surrounded by four e- pairs in four σ bonds, electron pair repulsion results in a tetrahedral structure, with a bond angle of 109.5 degrees

Question 26

Physical Properties of alkanes

Answer 26

• Alkanes have low melting or boiling points because of the very weak intermolecular forces between alkane molecules
• MP and BP increase with increasing chain length as there are more electrons in molecules, so more London forces
• insoluble in water, non-polar molecules, no points of attack for polar molecules

Question 27

Chemical properties of alkanes

Answer 27

• generally unreactive, harsh conditions needed to bring about a reaction

Question 28

Physical properties of alkenes

Answer 28

• MP and BP increase with increasing chain length and molecular weight
• MP and BP lower that respective alkanes, as they cannot pack together as well as alkanes, so less id:id forces are established, hence less energy is required
• insoluble in water

Question 29

Stereoisomers

Answer 29

compounds with the same structural formula but different spatial arrangement

Question 30

E/Z isomers

Answer 30

Restricted rotation about the C=C bond, and two different groups should be attached to each of the carbons in the double bond

Question 31

Cis-trans isomers

Answer 31

a special case where two groups attached to each C atom of the C=C bond are the same