Module 4

Question 1

whats a hydrocarbon

Answer 1

a compound containing carbon and hydrogen only

Question 2

saturated hydrocarbon

Answer 2

has single bonds only

Question 3

unsaturated hydrocarbon

Answer 3

contains double or triple bonds

Question 4

homologous definition

Answer 4

a family of compounds with similar properties whose successive members differ by the addition of a CH2 group

Question 5

whats a functional group

Answer 5

the part of the organic molecule that is largely responsible for the molecules chemical properties

Question 6

aliphatic definition

Answer 6

carbon atoms are joined to each other in unbranched or branched chains or non aromatic rings

Question 7

alicyclic definition

Answer 7

carbon atoms are joined to each other in ring structure with or without branches

Question 8

aromatic definition

Answer 8

some or all of the carbon atoms are found in a benzene ring

Question 9

alkynes

Answer 9

contain a triple bond

Question 10

empirical formula

Answer 10

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

Question 11

general formula

Answer 11

the simplest algebraic formula for any member of a homologous series

Question 12

molecular formula

Answer 12

shows the number and type of atoms of each element present in a molecule

Question 13

structural isomerism

Answer 13

compounds with the same molecular formula but different structural formulae

Question 14

homolytic fission

Answer 14

each of the bonded atoms takes one of the shared pair of electrons from the bond

Question 15

radical definition

Answer 15

an atoms or group of atoms with an unpaired electrons

Question 16

heterolytic fission

Answer 16

when a covalent bond breaks one of the atoms takes both the electrons from the bond

Question 17

curly arrows

Answer 17

show the movement of a pair of electrons

Question 18

the bonding in alkanes

Answer 18

only contain single bonds (saturated)
sigma bonds

Question 19

shape of alkanes

Answer 19

tetrahedral arrangement around each carbon atoms with a bond angle of 109.5

Question 20

boiling points in alkanes

Answer 20

as the chain length increases so does the boiling point as london forces act between molecules that are in close surface contact so as chain length increases the molecules have a larger surface area with more surfaace contact between molecules , so london forces will be greater

Question 21

affects of branching on boiling point of alkanes

Answer 21

branched isomers have lower boiling points as there will be fewer surface contact between molecules of the branched alkanes giving fewer london forces

Question 22

reactivity of alkanes

Answer 22

do not react with most common reagents because:
c-c and c-h sigma bonds are strong
c-c bonds are non-polar
c-h electronegativity is similar so baso non polar

Question 23

alkanes + halogens mechanism name

Answer 23

free radical substitution

Question 24

conditions for free radical sub

Answer 24

uv light

Question 25

what happens in initiation

Answer 25

covalent bond in a halogen molecule is broken by homolytic fission and 2 radicals are formed

Question 26

what happens in propogation

Answer 26

usually 2 steps where a halogen radical is reacting with an CH4 (as an example) to form CH3 and a hydrogen halide, this CH3 radical then reacts with eg br2 to from CH3Br and a br radical to react again with CH4

Question 27

what happens in termination

Answer 27

2 radicals collide forming a molecule with all electrons paired

Question 28

limitations of radical sub

Answer 28

further substitution
substitution at different positions in a carbon chain

Question 29

structure of alkenes

Answer 29

unsaturated hydrocarbons
pi bond which locks the 2 carbon atoms in position and prevents rotation

Question 30

whats a pi bond

Answer 30

the sideways overlap of 2 p orbitals above and below the carbon atoms

Question 31

conditions for E/Z isomerism

Answer 31

c=c
different groups attached to each carbon atom of the double bond

Question 32

Z isomerism

Answer 32

both priority groups are on the same side of the double bond

Question 33

E isomerism

Answer 33

the priority groups are on different side of the double bond

Question 34

priority groups in isomerism

Answer 34

the higher the atomic number the higher the priority

Question 35

cis/trans isomer

Answer 35

one of the attached groups on each carbon atom of the double bond must be the same

Question 36

cis isomer

Answer 36

baso same as z isomer , both groups on the same side

Question 37

trans isomer

Answer 37

baso same as a E isomer , groups on opposite side of the double bond

Question 38

reactivity of alkene

Answer 38

more reactive than alkanes because of the presence of the pi bond which as an electron dense area and so alkenes undergo addition reactions quite easily

Question 39

hydrogenation of alkenes

Answer 39

h2 and a nickel catalyst at 423k

Question 40

halogenation of alkenes

Answer 40

at rtp with a halogen

Question 41

testing for unsaturation

Answer 41

add bromine water to solution , if theres a double bond the solution turns colourless