1. Access to Science: Chemistry
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Access to Science: Chemistry
Arrange the cards on you bench into the correct homologous series
Organic 2

2. Learning aims: Recall important terms and prior learning.
Define the terms aliphatic, aromatic, unsaturated and saturated.
Name simple organic compounds
Define and draw the structures of chain, positional and functional group isomers.
State the use of alkane and some reactions

3. Important definitions
Homologous series:
is a family of compounds with the same general formula, similar chemical properties, each member differs by a –CH2- group
Functional group:
This is an active part of the molecule, where reactions with other chemicals tend to occur.

4. It is important to quote the right formula that is asked for:
Empirical formulae:
The lowest possible ratio of components in a formulae: e.g. C3H6 could be reduced to CH
Molecular formulae:C2H6O
Structural formulae:CH2=CHCH3
Displayed formulae:

5. Types of organic compounds
Saturated and unsaturated
In simple terms this means the absence or presence of double/triple bond(s) C H C H

6. Aliphatic and aromatic

7. Back to the beginning - alkanes
Remember the naming system: alkane (end in – ane)
All compound with 1 Carbon atom start: meth-
2 Carbon atoms eth –
3 Carbon atoms prop-
4 Carbon atoms but -
5 Carbon atoms pent-
6 Carbon atoms hex-
7 carbon atoms hept-
8 Carbon atoms oct-
9 Carbon atoms non-
10 Carbon atoms dec-

8. ETHANE C2H6
CH3CH3 C H

9. PROPANE C3H8
CH3CH2CH3 C H

10. BUTANE C4H10
CH3CH2CH2CH3 C H

11. PENTANE C5H12
CH3CH2CH2CH2CH3 C H

12. HEXANE C6H14
CH3CH2CH2CH2CH2CH3 C H

13. How do we name branched compounds?

14. Alkyl groups – take of the –ane and add -yl
Hydrocarbon
Alkyl group
Formula
methane
methyl
CH3-
ethane
ethyl
CH3CH2-
(C2H5-)
propane
propyl
CH3CH2CH2-
(C3H7-)
butane
butyl
CH3CH2CH2CH2-
(C4H9-)

15. Branched alkanes 1 CH3 CH2 CH 2-methylpentane main chain5 4 3 2 1
CH3
CH2 CH
main chain
methyl group attached to 2nd carbon atom of the main chain
2-methylpentane

16. Branched alkanes 2 CH3 CH2 CH 3-methylhexane
methyl group attached to 3rd carbon atom of the main chain 6 5 4 3
CH3
CH2 CH 2
main chain 1
3-methylhexane

17. Branched alkanes 3 1 2 3 4 5
CH3 CH
CH2
2,4-dimethylpentane

18. IUPAC naming rules Find the longest carbon chain, name it.
Identify which end of the chain where the most substituents are located and number the carbons from that end.
Consider all other carbon groups as substituents.
Alphabetize the substituents.
Substituents are named like a parent, and replacing the -ane ending with -yl.
More than one of the same substituents will be named, di-for 2, tri-for 3
Number the substituents according to the carbon to which they are attached. If numbering can be done in more than one way, use the numbering system that results in the smallest numbers.
Dashes appear between numbers and names, commas appear between numbers.
Let’s try some……

19. Name the following 1 2 3 4
(a)
CH3 CH
CH2
CH3
CH3
2-methylbutane

20. Name the following CH3 (b) CH3 CH CH2 CH2 CH3 CH3 2,2-dimethylpentane1 2 3 4 5
(b)
CH3 CH
CH2
CH2
CH3
CH3
2,2-dimethylpentane

21. Name the following 2 3 4
(c)
CH2
CH2
CH2
CH3
CH3 1 5
pentane

22. Name the following (d) CH3 CH2 CH CH3 CH3 CH2 3-methylpentane 2 1 3 54
3-methylpentane

23. More examples A) H H H H Br C C C C H H H H H B) H H H H Br C C C C Br
H CH3 H H practise some more…

24. Answers: A) methylpropane B) also methylpropane C) 2-chlorobutane
D) dimethylpropane
E) 2-methylbutane
F) 2,3-dimethylbutane
G) 2-bromo-2-chlorobutane
H) 3-dimethylhexane
I ) 2-butanol or butan-2-ol
J) 3-dibromo-2-dichloropentane
K) 2-hexene or hex-2-ene

25. Break

26. Isomerism
The branched chains look different to a straight chain compound because the atoms are ordered differently
They all have the same molecular formula: C5H12
But are arranged differently, this is called structural isomerism

27. Isomerism
The atoms of compound can be joined together in different ways these are defined as structural isomers.
There are 3 different types of structural isomerism
Chain, positional and functional group isomerism

28. Chain isomerism
This is when the carbon atom chain can be arranged differently, so the chain can look different
Can you see another way the
chain can be arranged.
Can you name it?

29. Remember start numbering carbon from the functional group end
Another examples
The different chain isomers of C4H8O2
H H O
H C C C
H CH3 O H
what would be their names?
Remember start numbering carbon from the functional group end

30. What isomers would occur of C5H12

31. Positional isomerism
This occurs when the substituents are attached to different carbon atoms, within the chain.
1-chlorobutane chlorobutane Cl

32. More
1-propanol propanol
1-butene butene

33. What about isomers of C5H11Br

34. Functional group isomerism
Here the molecular formula are the same, but the functional group is different
Ketones and aldehydes C3H6O
Also consider a new group esters and carboxylic acids: C3H6O2
methylethanoate pr propanoic acid

35. What about isomers of C5H10O

36. All these different compounds
Looking back at industry…
Research task: what are the uses of alkanes in industry?
Where do alkanes come from?
Explain how alkanes are produced from crude oil?
What reactions do alkAnes undergo?
Make an A4 poster to present to the class.