Organic Groups

Question 1

What are saturated hydrocarbons?

Answer 1

Alkanes (formed from only hydrogen & carbon with just single bonds)

Question 2

Are alkanes saturated or unsaturated hydrocarbons?

Answer 2

Alkanes are saturated hydrocarbons

Question 3

What’s the general formula for alkanes with no ring?

Answer 3

Cn H2n+2

Question 4

What type of bond do alkenes contain?

Answer 4

Double bond between carbon atoms

Question 5

What type of bond do alkynes contain?

Answer 5

Triple bond between 2 carbon atoms

Question 6

What are arenes?

Answer 6

Compounds that contain a benzene ring

Question 7

What are aliphatic compounds?

Answer 7

Compounds that don’t contain a benzene ring

Question 8

What are structural isomers?

Answer 8

Molecules with the same molecular formula (same number and type of atoms) but with different structures (atoms connected in a different order) they are different compounds with different properties

Question 9

What’s the general formula for cycloalkanes

Answer 9

Cn H2n (unless there’s more than 1 ring)

Question 10

What are small alkane molecules like? ( up to 4C)

Answer 10

Colourless gases

Question 11

What are medium (5 to 16C) alkanes like?

Answer 11

Colourless liquids

Question 12

What are large alkanes like?

Answer 12

White waxy solids

Question 13

Why are alkane molecules non-polar?

Answer 13

C & H have very similar electronegativity values

Question 14

Why are alkanes good fuels?

Answer 14

They don’t burn until ignited (have very high activation energies) & when they do burn a lot of energy is given out

Question 15

What is an alkene?

Answer 15

hydrocarbons which contain one or more C=C, they are therefore unsaturated

Question 16

what does a functional group determine?

Answer 16

how a molecule reacts

Question 17

what’s the formula for alkenes with one double bond and no rings?

Answer 17

CnH2n

Question 18

where do the shared pair of electrons of each covalent bond exist?

Answer 18

in a molecular orbital

Question 18

what are the two main types of molecular orbital?

Answer 18

sigma and pi

Question 18

how are atoms bonded together in molecules?

Answer 18

covalently

Question 19

where is the shared pair of electrons in a sigma bond?

Answer 19

directly between the 2 nuclei

Question 20

what’s the strongest type of covalent bond?

Answer 20

sigma bonds

Question 21

why are sigma bonds the most common type of covalent bond?

Answer 21

all single bonds are sigma bonds and the first bond of a double or triple bond will also be a sigma bond

Question 22

draw a double bond (as pi and sigma)

Answer 22

the weird burger thing

Question 23

what reaction do alkenes undergo?

Answer 23

electrophilic addition reactions

Question 23

why are C=C prone to attack by electrophiles?

Answer 23

it consists of 2 pairs of electrons so is very electron rich (high electron density & the pi bond sticks out above and below the plane of the molecule)

Question 24

define electrophilic addition reaction

Answer 24

an addition reaction where 2 molecules react to give just 1 product molecule (by adding together)

Question 24

what's the difference between a pi bond and a sigma bond?

Answer 24

a sigma bond is caused by the direct overlap of the p-orbitals of carbon atoms, pi bond are caused by the indirect 'leaning' overlap of p-orbitals

Question 25

which bond breaks when alkenes react?

Answer 25

the pi bond

Question 26

under which conditions do alkenes react with Br2 (both pure liquid bromine and br water)?

Answer 26

at room temperature and pressure

Question 27

how can you test for alkenes/unsaturated molecules?

Answer 27

add a few drops of bromine water (orange) and shake well, if the compound is unsaturated, a colour change from orange to colourless is seen

Question 28

draw the mechanism for electrophilic addition

Question 29

what is a carbocation?

Answer 29

a compound containing a carbon atom bearing a positive charge

Question 30

what conditions do you need to react an alkene with hydrogen bromide?

Answer 30

room temperature and pressure

Question 31

how many products will there be if a unsymmetrical alkene is reacted with hydrogen bromide?

Answer 31

2 (the bromine could be on either side of the carbon double bond)

Question 32

what are the reagents for a reaction between an alkene and water?

Answer 32

an alkene and water(steam) must include steam!

Question 33

what are the conditions to react an alkene an water?

Answer 33

high temperature, high pressure and a phosphoric acid catalyst

Question 34

what are the conditions needed to react an alkene with hydrogen?

Answer 34

platinum catalyst under room teperature and pressure or nickel catalyst with high temperature and pressure

Question 35

what is a cycloalkane?

Answer 35

alkanes with a ring of carbon atoms, with two hydrogens attached to each carbon

Question 36

why are benzene rings so stable?

Answer 36

the double bond electrons are delocalised around the carbon ring (they're not attached to any particular carbon atom)

Question 37

what's the general formula for an alcohol?

Answer 37

CnH2n+1OH

Question 38

Define an electrophile

Answer 38

A positive ion or molecule with a delta+ (slightly positive) region which is attracted to a negative region in a molecule, and reacts by accepting a pair of electrons to form a covalent bond