4.12 alkanes 4.13 alkenes

How do induces dipole-dipoles interactions form?

1. there are 2 xenon atoms, their electrons are moving constantly

2. at any one instant the electron cloud may be distributed unequally, this causes partially charges of delta+ and delta- to develop, instantaneous dipole forms

3. the instantaneous dipole on one atom induces a dipole on a neighbouring atom

4. there is electrostatic force of attraction between the delta- on one atom and delta+ on the other atom, these are induced dipole dipole attractions, they are present but are weak

why does butane have higher bp even though they have identical relative formula mass?

• methylpropane molecules cannot fit together as closely as butane molecules

• they have fewer points of surface contact

• so they have weaker london forces

what is the equation for complete using propane?

• C₃H₈ + 5O₂ = 3CO₂ +H₂O

what are the produces of complete combustion of alkanes?

• carbon dioxide

• water

What is the equation for incomplete combustion using ethane?

• 2C₂H₆ + 5O₂ = 4CO + 6H₂O

what is the products of incomplete combustion of alkanes?

• carbon monoxide

• water

why is production of carbon monoxide a problem?

• binds to haemoglobin in your blood better than oxygen

• so less oxygen reaches cells

• causes fatigue, headaches and nausea

• at high concentrations could become fatal

why do radicals have a dot?

• represent unpaired electron

what is homiletic fission usually started by?

• ultraviolet light

what are the 3 radical reaction types?

• initiation

• propagation

• termination

what is the definition of initiation?

• the first stage of radical reaction in which radicals form when a covalent bond is broken by homolytic fission

what is the formula for initiation?

• molecule =^uv radical + radical

how many initiation steps takes place?

• 1

what is the definition of propagation?

• the steps that continue a free radical reaction. The radical reacts with another reactant molecule to form a new radical and a new molecule

• forms a chain reaction

what is the formula for propagation?

• radical + molecule = molecule + radical

how many propagation steps take place?

• 2

what is the definition of termination?

• the steps at the end of a radical reaction where 2 radicals join to form a molecule

what is the formula for termination?

• radical + radical = molecule

how many termination steps are there?

• 3

what are stereoisomers?

• compounds with the same structural formula, but different arrangement of atoms in space

when does cis/trans isomerism take place?

• when there is a hydrogen and a different group on either side of a double bond

when is it cis isomerism?

• hydrogen are on same side

• (forms a c shape if you connect)

when is it trans isomerism?

• hydrogens are on different sides

what are the cahn-Ingold Prelog rules?

how do you know whether something is high or low priority?

• higher the atomic number of the atom attached to the double bond

• the higher the priority

• (if first atom is carbon on both double bonds, you look at the next atom along)

can cis/trans isomers also be E/Z isomers?

• yes