Module 4.1 Basic concepts and hydrocarbons Flashcards
1
Q
Homologous series
A
A series of organic compounds having the same functional group but with each successive member differing by CH2
2
Q
Functional group
A
Part of a molecule which determines how it reacts
3
Q
How do we name a alkane?
A
- add the prefix (first part of name) depending on how many carbon atoms
- then add -‘ane’ to the end
4
Q
How do we name a alkene ?
A
- add the prefix determined my how many carbon atoms there are
- number carbon atoms from the side where the double c=c bond will be the lowest
- add the c=c number
- end with ‘ene’
5
Q
How do we name branched chained hydrocarbons ?
A
- identify the longest carbon atoms
- number the carbon chain so the functional group sits on the lowest carbon number possible
- look at the side groups and determine which akyl group there are in and what carbon the sit on
- if there is more than one identical functionial group/side chain put di-2, tri-3 tetra-4
- name by the number on side group and alkyl name, the carbon chain name, carbon number the functional group is on and the suffix.
6
Q
General formula
A
The simplest algerbraic formula of a member of a homologous series
7
Q
Alkane general formula
A
CnH2n+2
8
Q
Alkene general formula
A
CnH2n
9
Q
Alcohols general formula
A
CnH2n+1OH
10
Q
Structual formula
A
The minimal detail that shows the arrangement of atoms in a molecule without showing bonds
11
Q
Sketetal formula
A
Shows just a carbon skeleton and functional groups. Hydrogen is not shown
12
Q
Display formula
A
- the relative positioning of atoms and bonds between them
13
Q
Prefix’s naming molecules
A
1- meth 2-eth 3-prop 4-But 5-pent 6-Hex 7-hept 8-oct 9-non 10-dec
14
Q
Alkyl groups
A
Hydrocarbon branches with the general formula CnH2n+1
15
Q
Aromatic compounds
A
- contains a benzene ring. They may have functional groups and alkyl groups coming from this
16
Q
Aliphatic compounds
A
- straight, branched chains or non aromatic rings with or without side chains
17
Q
Alycyclic compounds
A
- a aliphatic compound arranged in non-aromatic rings with or without side chains
18
Q
Unsaturated compound
A
- multiple carbon-carbon bonds
19
Q
Saturated compounds
A
- single carbon-carbon bond
20
Q
Structural isomers
A
- conpounds with the same molecular formula but differnt structural formulae. There are 3 types: chain, positional and functional group
21
Q
Chain isomerism
A
- compounds with the same molecular formula but different arrangement of the carbon skeleton
22
Q
Positional isomerism
A
- compounds with the same molecular formula but different position of functional group on the carbon skeleton
23
Q
Functional group isomerism
A
-compounds with the same molecular formula but different functional group
24
Q
Homolytic fission
A
Each bonding atoms reveives one electron from the bonded pair,
forming two radical
25
Heterolytic fisson
One bonding atom receiving both electrons from the bonded pair
26
Radicals
A species with an unpaired electron
27
What does the dot represent in a reaction mechanism?
- radicals
28
What does a curly arrow represent?
The movement of electrons
29
Properties of alkanes
- saturated hydrocarbon. Each carbon is bonded 4 times
- form a tetrahedral shape (109.5 degrees) because all the bonds repel each other equally.
- larger molecules (longer carbon chain) have more induced dipole-dipole forces due to having a larger electron cloud and more surface contact. so a higher boiling point.
- branched molecules have fewer induced dipole attraction due to fewer surface area interaction between molecules so have a lower boing point.
30
Why do alkanes have a low reactivity with many reagents?
- all covalent bonds in alkanes have high bond enthalpies
- the carbon-hydrogen sigma bonds have very low polarity as the electronegatibites of crabon and hydrogen are almost the same.
31
Complete combustion of alkanes
- burns completely in oxygen wgen there is a plentiful supply forming CO2 and H20.
32
Incomplete combustion of alkanes
- burns with a limited supply of oxygen producing carbon monoxide( CO) and carbon particles (soot)
33
3 main stages of radical substitution ( alkanes react with chlorine and bromine forming halogenated organic compound)
- inititation: radicals are produced normally using visible or UV light (photochemical reactions)
- propagation: when a radical reacts woth a non-radical molecules forming new radicals which go on to react with other non- radicaks.
- termination: two radicals react to make a stable non-radical molecule (chloromethane) ends reaction
34
Limitations of radical substitution
- forms a mixture of organic products. and side products ( multiple substitutions) therefore there is a low atom economy
Adding excess of the reactant can reduce the amount of substitutions. There is a greater chance of radical reacting with the product than another substance
- isomers are formed as free radical substitution can occur abywhere on a hydrocarbon chain
35
steroisomerism
molecules with the molecular formula but different arrangement of atoms in space
36
cis-trans isomerism
- naming isomer system
- carbon atoms on each side of the double bond must be bonded to 2 different groups and at least one of theses groups must be the same on both sides of the carbons on the double bond.
- find the group the same on both sides if the group are on the same side it is a CIS isomer
- if the group are on opposite sides its a TRANS isomer
37
using CIP rules to determine E/Z isomers
- assign priority to the highest atomic number group on both sides of the carbon atoms
- if the priority groups are on the same side its a Z isomer and on different sides its a Z isomer
38
Properties of alkenes
- trigonal planar shape (120 degree) The three bonding pair of electrons are in the plane of the molecule and repel each other equally
- stereoisomerism
- very reactive due to the Pi bonds having a high electron density and low bond enthaplys
39
E/Z isomerism
An example of steroisomerism, in terms of restricted rotation about a double bond and the reuirement for two different groups to be attached to each carbon atom of the C=C group
40
Cis-trans isomerism
A special case of E/Z isomerism in which two of the substituent groups attached to each carbon atom of the C=C group are the same.
41
Electrophile
An electron pair acceptir
42
The use of bromine to detect the presence of a double C=C bond
- Bromine is polarised as the electrons in the double repel the electrons in Br2 moving them to one side creating a dipole
- an electron pair in the double bond is attracted to the slighly positive bromine and form a bond. This breaks the Br-Br (heterlytic fission)
- a carbon cation intermediate is formed and Br is attracted to the C+
- this forms colourless dibromoethene
43
Hydrogenation
-hydrogen is added across a C=C bond. At 150 degree temp with a nickel catalyst. This saturated the alkene forming a alkane.
44
Hydrogen halides to form haloalkanes
- H-X is permanently polarised e.g HBR
- heterlytic fission breaks the bonds between HBR
- a carbon intermediate is formed and the Br- is attrated to the C+
45
addition reaction with steam
- addition reaction between gaseous alkene and steam. Used to make alcohols.
- conditions involve high temperatures and high pressures with a phosphoric acid catalyst
- reversible reaction with a inital reaction yield of only 5%. Any unreacted alkene is recycled through and an overall yield at 90-95% can be obtained overall
46
Markownikoffs rule
when H-X is added to an unsymmetrical alkene, the hydrogen becomes attached to the carbon with that is most stable than those with hydrogen atoms attached
47
reactions of alkenes
- very reactive due tom the pi bond which have a high electron density
- then Pi electrons are on the outside of the double bond this makes it easier to break as they are more exposed
- because the double bond breaks it is possible to add atoms/groups to the alkene
- undergo addition reactions with:
- hydrogen
- halogens
- hydrogen halides
- steam
48
combustion of energy production
- plastic can be burnt in power stations. the chemical energy transferred can be used to drive turbines and generate electricity.
49
organic feedstock
- waste polymers are broken down by chemical and thermal processes into monomers. Which can be used as the raw materials in the production of new polymers and other organic chemicals.
- benefit is it works well with unsorted and unwashed polymers
50
the benefits of biodegradable and photodegradable polymers
- biodegradable polymers can be broken down over time by microorganisms
- photodegradable polymers contain bonds that are weakened by absorbing light/visible radiation breaking down the polymer,.
- compostable polymers are commonly plant based .they degrade naturally leaving no harmful residues.
- bioplastics are polymers that are made from plant starch
