module 4 - chapter 13 key terms

Question 1

Alkenes

Answer 1

Alkenes are unsaturated hydrocarbons, they contain at least one carbon-carbon double bond. CnH2n

Question 2

Alkenes

Answer 2

Unsaturated hydrocarbons, they have at least one carbon-carbon double bond.

Question 3

Pi-bond

Answer 3

A pi bond is formed by the sideways overlap of two p-orbitals, one from each carbon atom of the double bond. Each carbon contributes one electron to the pair in the pi-bond. It locks the two carbons in position and stops them rotating around the double bond.

Question 4

Stereoisomers

Answer 4

Organic molecules with the same molecular formula and structural formula but having different arrangements of atoms in space.

Question 5

Cahn Ingold prolog rules

Answer 5

1) locate the double bond
2) On each carbon, look at the two substituents. Assign a priority to each group attached to the carbon based on its relative atomic mass. The highest priority group is the one with the highest relative atomic mass.
3) do the same with the other carbon, if the two highest priority groups are on the same side it is a Z isomer, if not its E.

Question 6

How to tell if something is a Z isomer?

Answer 6

If the two groups with the highest priority are on the same side of the double bond.

Question 7

How to tell if something in an E isomer?

Answer 7

If the two groups with the highest priority are on different sides of the double bond.

Question 8

Conditions for having E/Z isomerism

Answer 8

• a C=C double bond

- different groups attached to each carbon atom of the double bond

Question 9

Conditions for cis-trans isomerism

Answer 9

• must have a C=C double bond
• each carbon in the double bond must be attached to two different groups
• One of the groups must be hydrogen

Question 10

Cis-isomer

Answer 10

Hyrogens are on the same side of the double bond

Question 11

Trans-Isomer

Answer 11

Hydrogens are on different sides of the double bond.

Question 12

Electrophilic addition

Answer 12

The double bond represents a region of high electron density due to the pi-electrons. This attracts electrophiles, which leads to an addition reaction.

Question 13

Electrophile

Answer 13

Atom or group of atoms that is attracted to an electron-rich centre and accepts an electron pair.

Question 14

Carbocation

Answer 14

Contains a positively charged carbon atom.

Question 15

Markownikoff’s rule

Answer 15

When a hydrogen halide reacts with an unsymmetrical alkene the hydrogen of the halide attaches itself to the carbon atom of the alkene with the greater number of hydrogen atoms and smaller number of carbon atoms.

Question 16

Secondary carbocation

Answer 16

The positive charge is on a carbon atom with two carbon chains attached.

Question 17

Primary carbocation

Answer 17

The positive charge is on a carbon atom at the end of a chain

Question 18

Carbocation stability

Answer 18

The more alkyl groups the positive charge is attached to the more stable it is and therefore more likely it is to be made.

Question 19

Polymer

Answer 19

Large molecules made up of thousands of repeat units of smaller molecules know as monomers.

Question 20

Addition polymerisation

Answer 20

The addition of repeat units of monomers (unsaturated alkenes) to produce long saturated chains containing no double bonds. Different polymers have different properties depending on the monomer used. High molecular masses.

Question 21

Industrial polymerisation conditions

Answer 21

Carried out at high temperatures, high pressures and using catalysts.

Question 22

Repeat unit

Answer 22

The specific arrangement of atoms in the polymer molecule that repeats over and over again, it is always written in square brackets followed by n

Question 23

Poly(propene)

Answer 23

Formed from propene, used to make childrens toys, packaging, crates, guttering, uPVC windows and fibre for ropes.

Question 24

Poly(phenylethene)/ Polystyrene

Answer 24

Used for packaging material and also food trays and cups due to its thermal insulating properties.

Question 25

poly(tetrafluoroethene)

Answer 25

Used as a coating for non-stick pans, permeable membrane for clothing and shoes, and cable insulation.

Question 26

Feedstock recycling

Answer 26

Describes the chemical and thermal processes that can reclaim monomers, gases or oil from waste polymers. It is able to handle unsorted and unwashed polymers.

Question 27

Bioplastics

Answer 27

Bioplastics produced from plant starch, cellulose, plant oils and proteins offer a renewable and sustainable alternative to oil-based products. Protects environment, and conserves oil reserves.

Question 28

Biodegradable polymers

Answer 28

Polymers that can be broken down by microorganisms into water, carbon dioxide and biological compounds. Usually made from starch or cellulose, or contain additives that alter the structure of traditional polymers to allow the breakdown.

Question 29

Photodegradable polymers

Answer 29

When the use of plant-based polymers is not possible, photodegradable oil based polymers are being developed. These contain bonds that are weakened by absorbing light to start the degradation. Or light absorbing additives are used.

Question 30

Pi - bonds

Answer 30

formed by the sideways overlap of two p-orbitals, one from each carbon of the double bond. The pi-bond locks the carbon atoms in position and prevents them from rotating around the double bond, giving alkenes a different geometry.

Question 31

Stereoisomers

Answer 31

They have the same structural formula but different arrangements of the atoms in space.

Question 32

Conditions for E/Z isomerism

Answer 32

a C=C double bond

different groups attached to each carbon atom of the double bond.