1. Bonding in Hydrocarbons
Alkanes
Organic Compounds
Bonding in Hydrocarbons
Naming Alkanes
Empirical Formulae

2. biology…is that everything that animals do,
“The most important hypothesis in all of
biology…is that everything that animals do,
atoms do. In other words, there is nothing
that living things do that cannot be
understood from the point of view that
they are made of atoms acting according
to the laws of physics.”
Richard Feynman ( )

3. Organic Compounds Mainly contain carbon, oxygen, hydrogen
Found in living organisms hence the name organic compounds.
Huge implication in life sciences, medicine, biology, chemistry and many areas (such as winery)
~~~

4. Alkanes Contain C and H only Contain single bonds C-C
Have 4 bonds to every carbon (C) atom
Are nonpolar

5. Complete Structural Formulas
Show the bonds between each of the atoms
H H
 
H  C  H H C H
CH4 , methane
In methane, CH4 the four valence electrons of carbon are shared with the single electrons of four hydrogen (H) atoms. Each pair of electrons is a single bond, which can be drawn as a line. When a structure is drawn to show each bond, it is called a complete structural formula.

6. More Alkanes H H Condensed Structural Formulas H C C H CH3 CH3
H H Ethane
H H H
H C C C H CH3 CH2 CH3
H H H Propane
The complete structural formula for ethane shows the single bonds between two carbon atoms and six H atoms. The complete structural formula of propane shows the 3-carbon chain with single bonds to the attached H atoms. To write a condensed structural formula, the H atoms are written as a group next to their respective C atoms.

7. IUPAC Names Methane 1 CH4 Ethane 2 CH3CH3 Propane 3 CH3CH2CH3
Name # carbons Structural Formula
Methane 1 CH4
Ethane 2 CH3CH3
Propane 3 CH3CH2CH3
Butane 4 CH3CH2CH2CH3
Pentane 5 CH3CH2CH2CH2CH3
The names of organic compounds are determined by the IUPAC rules (International Union of Pure and Applied Chemistry). The stem of the name states the number of carbon atoms in the carbon chain of the compounds. The suffix, in this case –ane, indicates the alkane family.

8. IUPAC NAMES Hexane 6 CH3CH2CH2CH2CH2CH3
Name # carbons Structural Formula
Hexane CH3CH2CH2CH2CH2CH3
Heptane CH3CH2CH2CH2CH2CH2CH3
Octane CH3CH2CH2CH2CH2CH2CH2CH3
Nonane CH3 CH2 CH2CH2CH2CH2CH2CH2CH3
Decane 10 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3

9. Mother Eats Peanut Butter Perhaps Her Hair Often Needs Degreasing
Methane 
Ethane 
Propane 
Butane 
Pentane 
Hexane 
Heptane
Octane 
Nonane 
Decane

10. Naming Branched Alkanes
Parent chain is the longest
Position of branches is indicated by numbering carbons on parent chain
Number from the end that gets branch on lowest number
E.g.
H-C-C-C-C-C-C-H
H H H H CH3H
2-methylhexane
Not
5-methylhexane
H H H H H H

11. Naming Branched Alkanes
Alkyl gps (side chains) named similarly to alkanes e.g. Methyl, Ethyl etc…
More than one alkyl gp – di, tri, tetra
Numbers indicate position. Commas between numbers
Hyphen between number and letter
E.g. 2,2-dimethylbutane
H-C-C-C-C-H
H CH3H H
H CH3H H

12. Cycloalkanes CnH2n Carbons joined together in rings Saturated
homologous series (differ by number of CH2 units)
CnH2n

13. Structural Isomers
Same molecular formula but different arrangement of atoms.
E.g. C4H10

14. Practice Now watch this
Draw as many structural isomers as you can for:
C6H14 (5)
C8H18 (18)
Now watch this

15. Empirical Formula
The simplest whole number ratio of atoms of elements in a particle of a compound.
Can calculate empirical formula from the percentage composition by mass or ratio of constituent elements – of a compound

16. Empirical Formula
The ratio by mass can be converted to ratio by moles if the percentage figures are divided by the respective molar masses.
To calculate the ratio of numbers of atoms in the empirical formula, divide all the mole ratios by the smallest mole ratio
If one or more figures are decimals or fraction, multiply all figures by 2 or 3 or 4 etc. until the simplest whole numbers are produced.

17. Eg calculating empirical formula
Calculate the empirical formula of a compound of carbon and hydrogen containing 81.8% carbon and 18.2% hydrogen.