Chapter 12 Flashcards
what covalent bonds are found in an alkane?
sigma bonds
what is a sigma bond?
a direct overlap of the s orbitals
what is the bond angle in all alkanes?
109.5 degrees
effect of increasing chain length on boiling point
increasing carbon chain length increases the surface area
means more contact points for London forces
more London forces mean a stronger attraction between molecules which require more energy to overcome
HIGHER BP
effect of increased branching on boiling point
increased branching means fewer contact points for London forces
fewer London forces means weaker attraction which requires less energy to overcome
LOWER BP
why is there a lack of reactivity in alkanes?
the C-C and C-H bonds are strong
alkanes are all non-polar
what is the mechanism by which alkanes react with halogens?
radical substitution
what are the three stages of radical substitution?
initiation
propagation
termination
what are the two limitations of radical substitution?
further substitution
substitution at different points along the carbon chain
substitution at different points along the carbon chain
RS will produce a mixture of mono-substituted haloalkanes as the halogen can be bonded to any carbon along the carbon chain
further substitution
RS can continue to occur as it is a chain reaction which can lead to all hydrogen atoms being substituted