chemistry general revision (pt2) Flashcards
what are the steps of free readical reactions and what hapens in each step ?
-
Initiation
- homolitic fragmenetation of a weak bond in order to form 2 new free radicals -
Propagation
- more free radicals are produced
- redicals collide with alkane and removes H
- chain reaction continues endlessley in a cycle -
Termination
- free radicals are disrupted when there is a significant radical-radical combination reactions
what type of reaction is a free readical recation ?
a chain reaction
what is a condensation rection ?
a reaction in which 2 or more molecules combine into 1 molecule whilst also loosing a small molecule (e.g. water)
what is a hydrolysis reaction ?
a reaction wehre a molecule breaks down is smaller molecules with the help of another molecule (such as water).
nature of free radicals
5
- they are unstable
- short lived
- react very quickly
- exposed to intense ultra-violet radiation from the sun
- form and destroy the ozone layer
nature of a nucleophile
- Can donate electrom pairs
- Either negatively charge or neutrally charged
- undergo necleophillic addition and subtraction
- Also called Lewis bases
nature of eletrophiles
- can accept an electron pair
- either positively charged or neutrally charged
- either electrophillic addition or substitution reaction
- also called Lewis Bases
name structural isomers
they are 3
- chain isomers
- functional group isomers
- positional isomers
what is a chain isomer ?
A different arrangement of a molecule’s carbon skeleton
- rearranging the carbons can give branched carbon chains coming off the main chain, the name of the moclecule rflects this but fomula remains the same
- similar chemical properties and slightly different physical properties
what is a positional isomer ?
Different position of the same functional group in the molecule
* molecular formular remians the same, functional group also remians the same
* the name of the molecule chnages to refekct the posotion of the fucntional group
* similar chemical properties and slightly different physical properties
what is a functional group isomer ?
Differing postion of atoms give different functinal groups
* same molecuar formula but atoms re rearranged to give a different functional group
* name of the molecule chnages to reflect the new functional group
what are the 2 STEREOISOMERISMs ?
- optical isomers
- geometrical isomers
What are Geometrical Iosmers ?
- Different substituents around a bond with restricted rotation
-
Molecules with the same molecular formula and structural formula, but different shapes
* most common geometrical isomers are alkenes and cyclic compunds
* sometimes refered to as cis-trans isomers
* atoms in single covalent bonds in open chain compounds are able to undergo free rotation with respect to other
* distinct compounds with different physical properties melting points, boiling point and spectroscopic properties
what is E configuration in gemotrical isomers ?
E configuration – the highest priority groups are on the opposite side of the double bond
highest priority = highest atomic number
what is Z configuration in geometrical isomers ?
Z configuration = The highest priority groups are on the same side of the double bond
