Haloalkanes

Question 1

Electronegativity definition

Answer 1

Power or an atom to attract the 2 elections in a covalent bond

Question 2

3 factors effect ion electronegativity

Answer 2

Number of protons
Atomic radius
Shielding

Question 3

How does number of protons affect electronegativity?

Answer 3

Stronger attraction between negative electrons in bonding pair and positive nucleus

Question 4

How does atomic radius affect electronegativity ?

Answer 4

Closer the bonding pair to nucleus stronger the attraction

Question 5

How does shielding affect electronegativity ?

Answer 5

More shells between bonding pair and nucleus, weaker attraction

Question 6

Electron negativity down a group

Answer 6

Decreases

Question 7

Explaination for electronegativity down a group

Answer 7

• atoms bigger
• more shielding
• weaker attraction between bonding pair and nucleus
• decreases

Question 8

Electronegativity across a period

Answer 8

Increases

Question 9

Explaination for electronegativity across a period

Answer 9

• atoms smaller
• more protons
• stronger attraction between bonding pair and nucleus

Question 10

When does a non-polar covalent bond happen?

Answer 10

Two atoms in covalent bond have same electronegativity

Question 11

When do polar covalent bonds happen?

Answer 11

Two atoms in covalent bond have different electronegativity

Question 12

What is a non-polar covalent bond?

Answer 12

Covalent bond where 2 electrons are shared equally

Question 13

What is a polar covalent bond?

Answer 13

Covalent bond where the 2 electrons are not shared equally

The more electronegative the greater the electron share

Question 14

What is a bond dipole moment?

Answer 14

A measure of the strength + direction of the polarity in the bond

Question 15

What does the bigger difference in electronegativity mean for bond dipole moment?

Answer 15

The bigger the bond dipole moment

Question 16

3 things that determine electronegativity

Answer 16

• Nuclear charge
• Distance between nucleus + outer electron shell
• shielding by inner electron shells

Question 17

Electronegativity across a period

Answer 17

Increases

• more protons = stronger nuclear charge
• smaller atomic radius
• stronger attraction between nucleus + outer electron shell

Question 18

Electronegativity down a group

Answer 18

Decreases

• more shielding
• larger atomic radius
• weaker attraction between nucleus + outer electron shell

Question 19

bond polarity definition

Answer 19

Unequal sharing or electrons between atoms rhat are covalently bonded

Question 20

What is charge separation referred to as?

Answer 20

Dipole

Question 21

Test for polarity

Answer 21

Balloon next to tap

Question 22

3 types of halogen Alkanes

Answer 22

Primary
Secondary
Tertiary

Question 23

What are the haloalkane types dependant on?

Answer 23

Bonding in the carbon atom to which the halogen atom is bonded to

Question 24

What do bond enthalpies show?

Answer 24

Bond strongness

Question 25

How are halogen allowances formed?

Answer 25

When a halogen takes place of hydrogen in an alkane

Question 26

General halogen alkanes formula

Answer 26

CnH2n+1 (R-X)

Question 27

What can haloalkanes be used for?

Answer 27

Solvents (dry cleaning) Refrigerants Pesticides

Question 28

What is the ozone layer beneficial for?

Answer 28

it filters out mush of the suns harmful UV radiation

Question 29

What does CFCs stand for?

Answer 29

Chloroflurocarbons

Question 30

What do man made CFCs do?

Answer 30

Cause a hole in ozone lay a

Question 31

What do chlorine free radical atoms do?

Answer 31

Catalyse the decomposition of ozone

Question 32

Cl. free radical equation

Answer 32

Cl. + O3 -> ClO. + O2 ClO. + O3 -> 2O2 + Cl. 2O3 -> 3O2

Question 33

What does regenerated Cl radical mean?

Answer 33

Means 1 Cl radical could destroy many thousands of ozone molecules

Question 34

What bond is not affected by UV?

Answer 34

C-F

Question 35

Why is c=c bond not 120 degrees?

Answer 35

Higher density so repels H electrons

Question 36

What is a Z isomer?

Answer 36

Together

Question 37

What is an E isomer?

Answer 37

Opposite

Question 38

What is hydrolysis?

Answer 38

Splitting of a molecule using water

Question 39

What is the reactivity of the C-X bond?

Answer 39

- C-X bond broken when haloalkane reacts | - reactivity depends on how easy C-X bond is to break

Question 40

What 2 factors determine how easy C-X bond is to break?

Answer 40

- C delta + - X delta - bond polarity | - C-X bond enthalpy

Question 41

What results in a electron - deficient carbon?

Answer 41

More electronegative halogen removes charge from carbon it is bonded to

Question 42

What is electron - deficient carbon vulnerable to?

Answer 42

Vulnerable to attack by electron-rich reagents called nucleophiles

Question 43

What would we expect more reactive electronegative halogens to give?

Answer 43

More reactive haloalkanes

Question 44

What is the deciding factor for rate of hydrolysis?

Answer 44

Bond enthalpy

Question 45

Bond enthalpies from strongest to weakest

Answer 45

``` C-F C-H C-Cl C-Br C-I ```

Question 46

What will be more reactive is the bond polarity is important to the reaction?

Answer 46

R-F

Question 47

What will be more reactive is bond enthalpy is important to the reaction?

Answer 47

R-I

Question 48

What happens in a nucleophilic substitution reaction in hydrolysis?

Answer 48

A nucleophilic attacks a polar molecule + kicks out a functional group + settles itself down in its place

Question 49

General equation for nucleophilic substitution of halogen alkane

Answer 49

CH3CH2X + Nu- -> CH3 CH2 Nu+ X-

Question 50

What are the 3 nucleophiles

Answer 50

OH- (alcohol) CN- (nitrile) NH3- (amines)

Question 51

Hydrolysis of haloalkane method

Answer 51

``` Put test tubes of haloalkane + ethanol in hot water bath add silver nitrate White = chloride Cream = bromide Yellow = iodide ```

Question 52

What does R replete sent in nucleophilic substitution?

Answer 52

Alkyl group

Question 53

What does X represent in nucleophilic substitution?

Answer 53

Any halogen

Question 54

What does mechanism of nucleophilic substitution depend on?

Answer 54

Depends on C-X bonds strength

Question 55

What is a nucleophile?

Answer 55

A particle with a lone pair of electrons which can donate to form a bond

Question 56

Nucleophilic aubstitution steps

Answer 56

1) halogenoalkane undergoes nucleophilic substitution 2) lone pair of electrons on nucleophile attracted to electron deficient carbon 3) curly arrows show movement of pair of electrons 4) nucleophile causes electron in C-X bond to repel toward more electronegative halogen 5) forms halide ions

Question 56

Free radical 3 steps

Answer 56

First propagation step Second propagation step Termination

Question 57

Why do we use HFCs and not CFCs?

Answer 57

CFCs attached ozone layer + thinned down

Question 58

Structural isomer definition

Answer 58

Molecules with same molecular formula but different structures

Question 59

Acids, bases + alkali roles in elimination reaction in haloalkanes

Answer 59

Acid-proton donator Base-proton acceptor Alkali-soluble base

Question 60

What does nucleophilic substitution with haloalkane form?

Answer 60

Alcohol

Question 61

What happens when an OH- acts as a base?

Answer 61

Removes H+ from the haloalkane | Elimination rather than substitution

Question 62

Conditions for elimination

Answer 62

- heat - ethanol as a solvent (no water present) - concentrated potassium hydroxide