4B alkenes

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Single bonds have free rotations and are constantly rotating around binds true or false

True

C=C bonds have restricted rotation. They are unable to move

this results in stereoisomers existing for some alkenes true or false

Definition of stereoisomers

Molecules with the same structural formula but a different arrangement of atoms in 3d space

How are bonds formed in alkenes

When orbitals on two different atoms overlap

A single bond is called what

A sigma bond

What is a double bond called

Pi bond

consequences of pi bonding

geometric isomerism = two points overlap prevent C=C bond from rotating

Reactivity = electrons in pi bonds are more accessible for reactions

How do pi bonds form

the sideways overlap of p-orbitals above and below plane of atoms

Diagram of how pi bonds form

Which bond is stronger sigma or pi bond

sigma bond

When do E/Z isomers exist

When carbon of C=C bond has 2 different groups

How do you name E/Z isomers

•Check each C of C=C is joined to 2 different groups if so E/Z isomers exist •Draw a dashed line down vertically C=C •List atoms joined directly to each C of C=C and circle atoms with highest atomic number (they have the higher priority) •If both priority groups are on the same side of dashed line it i Z isomer

What do you do if two atoms have the same atomic number

List the atomic number of atom one bond further out and whichever one has the highest atomic number has higher priority

How do you know when to use cis or trans isomerism

Need the same group attached to both sides of C=C bond If the same groups are on the Same side it's cis If opposite side it's trans

E isomers pack more closely together meaning more contact area and stronger London forces true or false

True

Alkenes can undergo what reactions

Addition reactions

What is an addition reaction

A reactant is added to an unsaturated molecule to make one saturated molecule.

The two new groups of atoms always attach to the carbon in the double bond

What are the 4 addition reactions and what conditions need to happen for reaction to occur

Alkenes can react with a halogens eg: chlorine but it needs to be at room temperature and pressure

Alkenes can react with water (H2O). The conditions needed are steam (high temperatures) and H3PO4 catalyst or H2SO4 catalyst

Alkenes can react with H2 (hydrogen gas). The conditions needed are 150° and Nickel (Ni) catalyst

Alkenes can react with Hydrogen halide (most of the time it's HBr) but it has to be at room temperature and pressure

Asymmetric alkenes can react with HX to form 2 addition products true or false

True

How do you tell an alkene is assymetrical

On both sides of carbon double bond there is not the same molecule on the top or bottom half or even opposite

In addition reactions you can have more than one possible product true or false

True

What is electrophillic addiction

Reactions where alkenes react with hydrogen halides, halogens or h20

What is an electrophile

electron pair acceptor

In these reactions what is the electrophile

Hydrogen halides

What is a nucleophile

An electron pair donor

In these reactions what is a nucleophile

Alkene

What does the curly arrow show in electrophilic addition

Shows movement of a pair of electrons

Steps of electrophillic addition

1.)Double bond in alkene attracts electrophiles 2.) pi bond of C=C breaks. The pair of electrons from the pi bond make a new bond with delta + atom of electrophile 3.) delta + atom has too many bonds. The polar bond in electrophile breaks and the electrons move onto the delta - atom as a lone pair 4.) The bond is broken by heterolytic fission forming two ions

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Sometimes electrophile is not polar and you can do electrophillic addition with molevules like Br2 or H2 true or false

True

What is addition polymerisation

Joining together of many alkene monomers to form a polymer

When an alkene molecule has the square brackets and letter n what word do you put infront of the molecule

Poly

Polymers are derived from what

Crude oil

Alkene monomers join to form what

Polymers

How can we dispose plastics

Recycle them Can be put in landfill Can be burned to produce energy Can be broken down into monomers and used as a feedstock for organic reactions

Biodegradable polymers are broken down by what

Microorganisms

Photodegradable polymers are broken down by what

UV light

Types of Carbocations

Tiertiary (a carbon joined to 3 other carbons) Secondary (a carbon joined to 2 other carbons) Primary ( a carbon joined to 1 carbon)

Which carbocation is the most and least stable

Tiertiary = most Secondary = second most Primary = least

When in electrophillic addition when 2 products form the carbocation that is most stable forms what

Major product

When in electrophillic addition when 2 products form the carbocation that is least stable forms what

Minor product

Formula for atom economy

Total Mr of useful products/ Total Mr of all products x 100

Big numbers are involved as well

Formula for percentage yield

Actual mass of product / theoretical maximum mass of product x 100

How to calculate theoretical maximum mass of product

Calculate moles of reactant used Calculate maximum amount of moles by seeing ratio Calculate mass with moles and mr

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