Alkanes

What is hymolytic fission?

each of bonded atoms takes an electron

atom with unpaired electron is a radical

What is Heterolytic Fission

one of bonded atoms takes both the electrons and becomes a negative ion

What is an addition reaction?

2 reactants join to make 1 product

what is substitution reaction?

atom or group is replaced

what is elimination reaction?

removal of small molecule from larger molecule

Why are Alkanes not very reactive?

have strong polar C- C and non-polar C-H bonds

What happens to boiling point of alkanes as chain length increases?

-increases

-increased surface area of contact lead to greater london forces

-more energy needed to overcome them = higher boiling point

What happens to boiling point of alkanes when there are more branches?

-decreased

-decreased surface area of contact to weaker london forces

-little energy needed to overcome = lower boiling point

What is produced in complete combustion of alkanes?

carbon dioxide and water

What is produced in incomplete combustion of alkanes?

hydrogen atoms oxidised to form water

carbon not fully combusted to form carbon monoxide

What is the first step of bromination of alkanes?

-initiation

-covalent bond in bromine is broken by homolytic fission where energy is provided by UV and results in 2 highly reactive bromine radicals

What is the second step of bromination of alkanes?

-propagation

-bromine radical reacts with C-H bond in methane to form methyl radical + hydrogen bromine molecule

-methyl radical reacts with bromine molecule to form bromoethane + new bromine radical

What is the third step of bromination of alkanes?

-termination

-2 radicals collide to form a molecule with all paired electrons