Saturated or unsaturated?
Saturated
What type of bonds?
Sigma bonds
General formula?
CnH2n+2
Polar or non-polar?
Non-polar as the electronegativities of carbon and hydrogen are very similar
Do alkanes attract nucleophiles?
No as they have no electron-deficient areas to attract them
Do alkanes attract electrophiles?
No as they have no electron-rich areas
What bonding and arrangement?
Tetrahedral bonding arrangement with a bond angle of 109.5
4 bonding pairs
What forces?
London forces- induced dipole dipole
What does the boiling point vary with?
Chain length
Branching
Chain length?
ID-ID forces are small for a small alkane but will increase as the size of the molecule increases
Therefore the boiling point of the alkane increases with the molecular size, due to the increased dipole-dipole forces
Branching?
Lower boiling points than unbranched alkanes containing the same number of carbon atoms
ID-ID can only operate over very short distances between 1 molecule and its neighbouring molecules
Unbranched have greater IMF- greater SA
Are alkanes reactive or unreactive?
Unreactive because of the C-C and the C-H bonds
The low polarity of the sigma bonds present
When does complete combustion occur?
In plenty of oxygen- forms carbon dioxide and water
What happens when alkanes are burnt in a limited supply of oxygen?
Incomplete combustion forms, forming carbon monoxide
What are sigma bonds?
Overlap of orbitals directly between the bonding atoms
Straight chain alkanes boiling point?
Carbon chain length increases:
More electrons and more points of contact between molecules
Strength of London forces between the molecules increases
More energy needed to break the IMF
Branched chain alkanes boiling points?
Fewer points of contact between the molecules
Strength of London forces between the molecules decreases
Less energy needed to break the IMF
Are alkanes polar or non polar
Non polar
Will alkanes dissolve in polar solvents like water?
No however they will mix with non polar solvents
