Basic concepts and hydrocarbons

Question 1

what is the structural formula

Answer 1

minimal detail showing the arrangement of atoms in a molecule

Question 2

what is the displayed formula

Answer 2

relative positioning of atoms and the bonds between them

Question 3

what is the skeletal formula

Answer 3

simplified organic formula - removes hydrogen leaving carbon skeleton and associated functional groups

Question 4

what is a homologous series

Answer 4

series of organic compounds with the same functional group, but differing by CH2

Question 5

what is an alkyl group

Answer 5

alkane chain with a hydrogen removed

Question 6

definition of an aliphatic compounds

Answer 6

chain of carbon and hydrogen atoms that can be straight, branched or non-aromatic rings

Question 7

definition of an alicyclic compound

Answer 7

aliphatic compounds arranged in non-aromatic rings or without side chains

Question 8

definition of an aromatic compound

Answer 8

a compound containing a benzene ring

Question 9

difference between saturated and unsaturated

Answer 9

saturated) single carbon carbon bond
unsaturated) more than one carbon carbon bond eg double, triple

Question 10

what is a structural isomer

Answer 10

compounds with the same molecular formula but different structural formula

Question 11

what is a stereoisomer

Answer 11

molecule with the same molecular formula but different arrangement of atoms in space

Question 12

describe the 3 types of structural isomers

Answer 12

chain - differ in skeleton arrangement
position - functional group attached at different carbon atoms
functional - atoms form different functional groups

Question 13

describe homolytic fission

Answer 13

a covalent bond breaking, each bonding atom receives an electron pair forming 2 radicals
X-Y = X* + Y*

Question 14

describe heterolytic fission

Answer 14

a covalent bond breaking unevenly, one bonding atom receives both electron pairs
X-Y = X+ + Y-

Question 15

what is a radical

Answer 15

a species with an unpaired electron, represented by a dot

Question 16

what does a curly arrow represent

Answer 16

movement of an electron pair, shown in either heterolytic fission or formation of a covalent bond

Question 17

what is a reaction mechanism

Answer 17

they depict the sequential steps through which reactants transform into products. They employ curly arrows to represent the movement of electron pairs during the formation and breaking of bonds

Question 18

difference between primary, secondary and tertiary carbocation?

Answer 18

depends on how many carbon atoms are bonded to the positively charged carbon
primary - 1
secondary - 2
tertiary - 3

Question 19

what is Cis/Trans isomerism

Answer 19

special type of E/Z isomerism where the 2 substituents on the carbon atom are the same

Question 20

how is a covalent bond formed from 2 radicals

Answer 20

the radicals collide and the electrons are involved in the bond formation

Question 21

are alkanes polar
why

Answer 21

no because carbon and hydrogen have similar electronegativities

Question 22

shape and angle of an alkane?

Answer 22

tetreahedral
109.5

Question 23

describe sigma bond in a alkane

Answer 23

a covalent bond directly overlapping of the electron orbital clouds of the bonding atoms

Question 24

what type of intermolecular forces do alkanes have and why

Answer 24

-London forces/induced dipole-dipole bc bonds are non polar

Question 25

describe boiling point of alkanes as chain length increases

Answer 25

increases due to more dipole-dipole interactions , meaning more energy needed to overcome the attraction

Question 26

describe boiling point of alkanes as side chains increase

Answer 26

decrease due to less surface area, so less dipole-dipole interactions, meaning less energy is needed to overcome them

Question 27

are alkanes soluble in water and why

Answer 27

no - because their hydrogen bonding is stronger than their London forces of attraction

Question 28

how reactive are alkanes

Answer 28

very unreactive due to strong covalent bonds and non polar bonds

Question 29

what reactions will alkanes undergo

Answer 29

-combustion -reaction w halogens

Question 30

products of complete combustion of alkanes

Answer 30

carbon dioxide and water

Question 31

colour of bunsen flame during complete combustion

Answer 31

blue

Question 32

products of incomplete combustion of alkanes

Answer 32

carbon dioxide, water vapour, carbon monoxide and carbon soot

Question 33

are longer or shorter chains more likely to undergo incomplete combustion

Answer 33

longer chains because the oxidation reaction of combustion requires more oxygen

Question 34

how are halogenalkanes formed from alkanes and what does it require

Answer 34

radical substitution requires uv light

Question 35

what are the 3 stages of radical substitution

Answer 35

initiation - breaking halogen bond to form free radicals propagation - chain part where products are formed but free radical remains termination - free radicals removed, stable products form

Question 36

what's the formula for radical substitution of alkanes

Answer 36

alkane + hydrogen = halogenalkane + hydrogen halide

Question 37

how is a pi bond in alkenes formed

Answer 37

electrons in adjacent p orbitals overlap above and below carbon atoms. they can only be made after a sigma bond is formed

Question 38

what bond restricts rotation on carbon atoms in alkenes

Answer 38

pi bond

Question 39

angle and shape of double bond

Answer 39

trigonal planar 120

Question 40

why are alkenes more reactive than alkanes

Answer 40

high electron density of double bond and pi bonds are slightly easier to break because they overlap adjacently

Question 41

what type of intermolecular forces do alkenes have and why

Answer 41

only London forces due to non-polar bonds and no permanent dipoles

Question 42

are alkenes soluble in water and why

Answer 42

no due to non polar bonds ( C and H similar in electronegativity )

Question 43

what is an electrophiles and nucleophiles

Answer 43

electrophile - electron pair acceptor nucleophile - electron pair donator

Question 44

what is the most stable type of carbocation intermediate

Answer 44

alkyl groups have a positive inductive effect - so the most stable is the one bonded to the most other carbon atoms, eg tertiary carbocation

Question 45

what kind of carbocations are major products formed from

Answer 45

tertiary / most stable available

Question 46

conditions for H2O to react w alkene? what is the reaction called and what are its products

Answer 46

steam in the presence of an acid catalyst, usually phosphoric acid hydration forms an alcohol

Question 47

conditions for electrophilic addition of a hydrogen halide to an alkene?

Answer 47

hydrogen halide gases must be at room temperature

Question 48

name for reaction of halogen added to an alkene

Answer 48

halogenation

Question 49

how does a molecule with non polar bond act as an electrophile

Answer 49

C=C double bond w/ high electron density induces a temporary dipole in the halogen molecule then delta + atom is attracted to the double bond

Question 50

explain markovnikovs rule

Answer 50

in electrophilic addition of a hydrogen halide to an alkene, the hydrogen will attach to the carbon with the most hydrogens attached to it, and the carbon will attach to the carbon with the least hydrogens attached to it

Question 51

explain hydrogenation

Answer 51

alkene + hydrogen = alkane requires 150C and nickel catalyst

Question 52

what is an addition polymer

Answer 52

many monomers bonded together via rearrangement of bonds without loss of atom/molecule

Question 53

what are monomers

Answer 53

molecules which combine to form a polymer from repeating units -usually have C=C bond which breaks to leave a repeating pattern

Question 54

what is combustion

Answer 54

reaction between fuel and oxygen releasing energy as heat

Question 55

What is the ester functional group

Answer 55

R-C=O-O-R