1. Organic Compounds
the origin of crude oil and its use as a source of hydrocarbon raw materials
the grouping of hydrocarbon compounds into families (alkanes, alkenes, alkynes, alcohols, carboxylic acids and non-branched esters) based upon similarities in their physical and chemical properties including general formulas, their representations (structural formulas, condensed formulas, Lewis structures), naming according to IUPAC systematic nomenclature (limited to non-cyclic compounds up to C10, and structural isomers up to C7) and uses based upon properties
determination of empirical and molecular formulas of organic compounds from percentage composition by mass and molar mass.

2. Boardworks AS Chemistry Introducing Organic Chemistry
Carbon is an unusual atom in that it is able to form four very strong covalent bonds with other carbon atoms.
When we then include it’s ability to also bond with other elements we open up the possibility of the highly diverse and complex molecules (like DNA) that have led to the possibility of life.
Because of this, the chemistry of carbon containing compounds is often called organic chemistry.

3. Fractional distillation
Boardworks AS Chemistry
Alkanes
Fractional distillation

4. Boardworks AS Chemistry Alkanes
Uses of fractions
Teacher notes
The exact composition of each fraction in terms of chain length varies from source to source.

5. Fractions and boiling point
Boardworks AS Chemistry
Alkanes
Fractions and boiling point

6. Boardworks AS Chemistry Alkanes
Crude oil and alkanes
Boardworks AS Chemistry
Alkanes
Crude oil is a mixture composed mainly of straight and branched chain alkanes.
It also includes lesser amounts of cycloalkanes and arenes, both of which are hydrocarbons containing a ring of carbon atoms, as well as impurities such as sulfur compounds.
The exact composition of crude oil depends on the conditions under which it formed, so crude oil extracted at different locations has different compositions.
Photo credit: George Spade / shutterstock.com
Oil pumps in West Siberia.

7. Boardworks AS Chemistry Alkanes
What are alkanes?
The alkanes are a homologous series of hydrocarbons with the general formula CnH2n+2 and names ending –ane.
Alkanes contain only single carbon–carbon bonds and so are saturated.
C5H12
pentane
C4H10
butane
C3H8
propane
C2H6
ethane
CH4
methane
C6H14
hexane 5 4 3 2 1
Name
No. of carbon atoms
Molecular formula 6
Teacher notes
See the ‘Introducing Organic Chemistry’ presentation for more information about homologous series, general formula and molecular formula.

8. Boardworks AS Chemistry Alkanes
What are alkanes? C H
methane, CH4 C H
propane, C3H8
pentane, C5H12 C H
Teacher notes
See the ‘Introducing Organic Chemistry’ presentation for more information about homologous series, general formula and molecular formula.

9. Representing organic molecules
Boardworks AS Chemistry
Introducing Organic Chemistry
The molecular formula of a compound shows the number of each type of atom present in one molecule of the compound.
CH2O
C2H4O2
C6H12O6
CH3
C2H6
Empirical formula
Molecular formula
The empirical formula of a compound shows the simplest ratio of the atoms present.
Neither the molecular nor empirical formula gives information about the structure of a molecule.

11. Structural formula - full
Boardworks AS Chemistry
Introducing Organic Chemistry
Structural formula - full
The full structural formula of a compound shows the arrangement of atoms in a molecule, as well as all the bonds.
Single bonds are represented by a single line, double bonds with two lines and triple bonds by three lines
The full structural formula can show the different structures of compounds with the same molecular formulae.
ethanol (C2H6O)
methoxymethane (C2H6O)

12. Structural formula - condensed
Boardworks AS Chemistry
Introducing Organic Chemistry
Structural formula - condensed
The condensed structural formula shows all the atoms and their relative positions but bonds are omitted. Double or triple bonds may be shown.
CH3CHClCH3
2-chloropropane
H2C=CH2
ethene
CH3C≡N
ethanenitrile

13. Structural formula - skeletal
Boardworks AS Chemistry
Introducing Organic Chemistry
The skeletal formula of a compound shows the bonds between carbon atoms, but not the atoms themselves. Hydrogen atoms are also omitted, but other atoms are shown.

14. Boardworks AS Chemistry Introducing Organic Chemistry
What is isomerism?
Isomers are molecules with the same molecular formula (i.e. the same number and type of atoms) but in which the atoms are arranged in a different way.
For now we will learn about structural isomerism
Structural isomers have the same molecular formula but different structural formulae.
Three types of structural isomerism are chain isomerism, positional isomerism and functional group isomerism.

15. Chain isomerism in alkanes
Boardworks AS Chemistry
Introducing Organic Chemistry
Chain isomerism in alkanes
In chain isomers, the carbon chain is arranged differently. For example, hexane has several chain isomers, all with the molecular formula C6H14:
hexane
Teacher notes
The isomer hexane is sometimes referred to as n-hexane.
Students could be asked to draw the remaining two isomers of hexane: 2-methylpentane and 2,2-dimethylbutane.
2,3-dimethylbutane
3-methylpentane

16. Naming alkanes 1. Number and name the longest chain of carbon atoms
2. Look for the branches. di-, tri etc used for more than one branch of same kind. Write branches in alphabetical order
3. Find the number of the carbon atom to which the branch is attached. (Number from whichever end gives the lowest numbers)
4. Complete by adding the number and name of the branch to the carbon chain. Put comma's between numbers eg 2,2 or 2,3. Hyphens separate numbers from letters eg 2,2-dimethyl. No gaps between names eg methylpropane

17. Boardworks AS Chemistry Alkanes
Complete combustion
In excess oxygen, short chain alkanes can undergo complete combustion:
alkane + oxygen → carbon dioxide + water
For example:
propane + oxygen → carbon dioxide + water
C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(g)
Teacher notes
See the ‘Energetics’ presentation for more information about exothermic reactions.
The combustion of alkanes is a highly exothermic process. This makes them good fuels because they release a relatively large amount of energy per gram of fuel.

18. Incomplete combustion
Boardworks AS Chemistry
Alkanes
If oxygen is limited then incomplete combustion will occur:
alkane + oxygen → carbon monoxide + water
alkane + oxygen → carbon + water
For example:
propane + oxygen → carbon monoxide + water
C3H8(g) + 3½O2(g) → 3CO(g) + 4H2O(g)
Teacher notes
Students could be reminded that carbon monoxide is a colourless and odourless, highly toxic gas and that carbon from incomplete combustion is known as soot.
propane + oxygen → carbon + water
C3H8(g) + 2O2(g) → 3C(s) + 4H2O(g)

19. Trends in boiling points
Boardworks AS Chemistry
Alkanes
Trends in boiling points