Halogenoalkanes - introductions

Question 1

What is the general formula for a halogenoalkane with a single halogen atom?

Answer 1

CnH2n+1X (X is the halogen)

Question 2

What are the 4 halogens?

Answer 2

Flourine
Chlorine
Bromine
Iodine

Question 3

What are the prefixes for the 4 halogens?

Answer 3

Fluoro-
Chloro-
Bromo-
Iodo-

Question 4

What is the symbol for flourine?

Answer 4

F

Question 5

What is the symbol for chlorine?

Answer 5

Cl

Question 6

What is the symbol for bromine?

Answer 6

Br

Question 7

What is the symbol for iodine?

Answer 7

I

Question 8

The symbol F is for which element?

Answer 8

Flourine

Question 9

The symbol Cl is for which element?

Answer 9

Chlorine

Question 10

The symbol Br is for which element?

Answer 10

Bromine

Question 11

The symbol I is for which element?

Answer 11

Iodine

Question 12

Are the carbon-halogen bonds polar or non-polar?

Answer 12

Polar (C+_X-)

Question 13

What is more electronegative? The carbon or the halogen?

Answer 13

The halogen

Question 14

Do the electrons want to be closer to the carbon or the halogen?

Answer 14

The halogen

Question 15

As you go down the group of the halogens what happens to the bond polarity?

Answer 15

They get less polar

Question 16

Why aren’t the halogens soluble in water?

Answer 16

Because the bonds are not polar enough

Question 17

What are the main intermolecular forces of attraction between the carbon and halogens?

Answer 17

Dipole-dipole attractions and van der Waal forces.

Question 18

Because halogenoalkanes can mix with hydrocarbons what can they be used for?

Answer 18

dry-cleaning fluids and to remove oily stains (oil is a mixture of hydrocarbons).

Question 19

What is another word for halogenoalkanes?

Answer 19

Haloalknaes

Question 20

What does the boiling point of the halogenoalkane depend on?

Answer 20

The number of carbon and halogen atoms

Question 21

What happens to the boiling point as the chain length increases?

Answer 21

The boiling point increases

Question 22

How does the boiling point change going down the halogen group?

Answer 22

The boiling point increases

Question 23

Why does the boiling point increase with increased chains and when you go down the halogen group?

Answer 23

Because the van der Waals forces increase because the larger the molecule the greater the number of electrons and thus the larger the van der waals forces

Question 24

Why do halogenoalkanes have higher boiling points than other alkanes with similar chain lengths?

Answer 24

Because they have higher relative molecular masses and they are more polar.

Question 25

What are the two factors that determine how easily the C-X bond will break?

Answer 25

The C+_X- bond polarity | The C-X bond enthalpy

Question 26

What is a nucleophile?

Answer 26

An electron pair donor

Question 27

Which of the halogens is the most delta negative?

Answer 27

Flourine

Question 28

Which carbon-halogen bond is the most polar?

Answer 28

C-F2

Question 29

Why is C-F bond the most reactive?

Answer 29

It is the most polar, so the C+ has the most positive charge and is therefore most easily attacked by a nucleophile.

Question 30

Which Carbon-halogen bond is the least reactive?

Answer 30

C-I

Question 31

What happens to the bond enthalpy as you go down the halogens?

Answer 31

They decrease

Question 32

Why do the bond enthalpies decrease as you go down the halogen group?

Answer 32

Because the shared electrons get further and further away from the halogen nucleus, so the bond becomes weaker.

Question 33

What happens to the reactivity going down the halogen group?

Answer 33

It increases

Question 34

Which out of bond enthalpy and bond polarity is the more important factor in how reactive a carbon-halogen bond is?

Answer 34

Bond enthalpy