Topic B3 - Alkenes

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Total cards: 23•Content version: v4•Public deck•Updated: 8/1/2026

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Front (Question)

What bonds are present in alkenes?

Back (Answer)

-sigma bonds -pi bonds

Front (Question)

What is the shape of each c–c bond and its bonded hydrogens?

Back (Answer)

-trigonal planar -120 -4 bonding pairs -2 single bonds, 1 double bond -double bond repels more than single bond

Front (Question)

Why is pi bond weak?

Back (Answer)

electron density spread over a wider distance

Front (Question)

Where is pi bond found?

Back (Answer)

double carbon-carbon bond

Front (Question)

What does stereoisomers mean?

Back (Answer)

same structural formular but a different arrangement of atoms in space

Front (Question)

How does stereoisomerism arise?

Back (Answer)

due to rotation around double bond being restricted, so groups around carbon are fixed to each other

Front (Question)

How do you identify E isomerism?

Back (Answer)

-ensure both sides of double bond contain 2 different side chains -assign priority groups (highest atomic number = top priority) -if top priorities are on different sides, then it is E isomerism

Front (Question)

How do you identify Z isomerism?

Back (Answer)

-ensure both sides of double bond contain 2 different side chains -assign priority groups (highest atomic number = top priority) -if top priorities are on same side, then it is Z isomerism

Front (Question)

Addition reactions: with hydrogen conditions

Back (Answer)

-hydrogen -nickel catalyst -423k (temp)

#10

Front (Question)

Addition reactions: with hydrogen example

Back (Answer)

propene ——> propane

#11

Front (Question)

Addition reactions: with steam conditions

Back (Answer)

-add steam -phosphoric acid catalyst (or conc. sulfuric acid)

#12

Front (Question)

Addition reactions: with steam example

Back (Answer)

propene + steam —-> propan-1-ol or propan-2-ol

#13

Front (Question)

Addition reactions: with hydrogen halides conditions

Back (Answer)

-room temperature -gaseous hydrogen halide

#14

Front (Question)

Addition reactions: with hydrogen halide example

Back (Answer)

prop-1-ene + hydrochloric acid —-> 1-chloropropane or 2-chloropropane

#15

Front (Question)

What is an electrophile?

Back (Answer)

electron pair acceptor

#16

Front (Question)

What do curly arrows in an electrophile mechanism show?

Back (Answer)

movement of electron pairs

#17

Front (Question)

How do you work out the major product of a reaction?

Back (Answer)

-more stable carbocation -more alkyl groups attached to charged carbon atom, means charge is more spread out so ion is more stable

#18

Front (Question)

What bond breaks during addition polymerisation?

Back (Answer)

double bond (pi bond)

#19

Front (Question)

How are waste polymers used for energy production?

Back (Answer)

-combustion -incinerated to produce heat -generates steam to turn turbine

#20

Front (Question)

How are waste polymers used for organic feedstock?

Back (Answer)

-chemical and thermal processes reclaim monomers -materials produced as raw materials for new polymers

#21

Front (Question)

How is toxic waste removed from waste polymers?

Back (Answer)

solvents dissolve polymer and precipitation of solvent removes polymer

#22

Front (Question)

Biodegradable polymers

Back (Answer)

-broken down by microorganisms to produce carbon dioxide/ water/ biological compounds -compostable polymers leave no toxic residue (e.g. shopping bags made from plant starch)

#23

Front (Question)

Photodegradable polymers

Back (Answer)

bonds weakened by absorbing light