alkyl halides mod3

define electronegativity:

atoms ability to attract electrons towards itself in a covalent bond

explain what an alkyl halide is:

hydrocarbons in which one or more of the hydrogen atoms have been replaced by a halogen atom

explain the non polar bonds in alkyl halide:

C-C and C-H bonds are non polar

no part of molecule is more negative or positive than the other

give examples of polar bonds:

C-X, C-O, C=O, O-H, N-H

explain the polar bonds in alkyl halide:

electrons of the bond spend more time closer to one of the atoms than the other atom

one part of the molecule is slightly negatively charged, the other slightly positive

explain dispersion forces:

if electrons randomly congregate at one end of the bond, that end is slightly negative and the other is slightly positive

explain attraction of dispersion forces and strength:

a passing molecules electrons will be attracted to the slightly positive end of the first molecule

weak, short lived attraction

explain dipole-dipole electrons:

electrons are always to the halogen atom than the carbon atom, one end slightly positive the other slightly negative

explain attraction of dipole-dipole forces and strength:

neighbouring molecules will attract each other with this dipole-dipole force

medium strength, permanent attraction

compare dispersion forces and di-di forces:

di-di are much stronger, harder to break so MP and BP are increasing

where are halogens found:

located in group 17, more electronegative than carbon

properties of alkyl halides:

• sweet smelling

• MP and BP increase with molecular weight

• denser than water

• good solvents for non-polar solutes

why do alkyl halides have a higher MP and bP than hydrocarbons of similar molecular weight:

stronger IMF, has di-di forces rather than just dispersion

why are alkyl halides good solvents for non-polar solutes?

because of long-ish hydrocarbon portion and small polar portion

uses of alkyl halides:

solvents and cleaning fluids

aerosol propellants and coolants

explain alkyl iodides:

most reactive

bond takes least energy to break and distance between carbon and iodine is already large = easy to seperate atoms

explain alkyl fluorides:

least reactive

bond takes more energy to break, distance between C-F atoms is small, they are attracted to each other and harder to seperate

explain teflon:

great for non-stick applications as bond energy is very high and atoms are close together, makes it hard to break bonds and hard to move apart

explain priority of alkyl and halides when naming:

halogens and alkyl branches are equally important

synthesis of alkyl halides in alkanes:

one hydrogen atom is replaced by a halogen atom

needs UV light

explain synthesis of alkyl halides in alkenes:

does addition reactions such as:

• halogenation

• hydrohalogenation

explain markovnikovs rule:

hydrogen atom goes to the carbon which already has the most hydrogen atoms directly bonded to it

define nucleophile:

negatively charged species that are attracted to positively charged things

define electrophile:

positively charged species that are attracted to negatively charged things

explain a nucleophilic substitution reaction:

nucleophile attacks alkyl halide, substituting itself for the halogen atom that was already there

explain elimination reaction:

a strong base attacks alkyl halide, removing a hydrogen

alkyl halide then expels a halide to make an alkene