4.1 BASIC CONCEPTS & HYDROCARBONS Flashcards
State what functional groups are responsible for
- the reactions of a compound
Define homologous series
- A series of organic compounds with the same functional group, similar chemical properties and each successive member differing by CH2
Define homolytic and heterolytic fission
- Homolytic fission is when a covalent bond breaks equally to give each atom an electron and form two radicals
- Heterolytic fission is when a covalent bond breaks and one atom takes both electrons to form a positive and negative ion
Describe the route of curly arrows
- Movement of a pair of electrons from a lone pair,bond or negative charge to an atom
Define radical
- A highly reactive species with an unpaired electron
Define electrophile
- An electron pair accepting species with postive/δ positive charge, attracted to areas of electron density
Define nucleophile
- An electron pair donating species with negative/δ negative charge, attracted to electron deficient areas
Define structural isomerism
- Compounds with the same molecular formula but different structural formula
State the three types of structural isomerism
- functional group isomerism
- chain isomerism
- positional isomerism
Define stereoisomerism
- Compounds with the same molecular formula and same structural formula but different arrangementof atoms in space
State the two features required for cis/trans isomerism
- Unsaturated C=C bond
- Atleast two atom groups to be the same
State the two features required for E/Z isomerism
- Unsaturated C=C bond that has restricted rotation
- Each carbon atom of the double bond is attached to two different atoms/atom groups
Draw E/Z isomerism
Draw cis/trans isomerism
State the 4 ways of disposing polymers
- Use as organic feedstock
- Recycling
- Combustion
- Landfill
State the 2 environmental polymers
- photodegradable
- biodegradable
Explain the shape and bond angle of alkanes
- Tetrahedral
- 109.5°
- All four bonding pairs of electron regions repel equally
3 properties of alkanes
- Non-polar
- MP/BP increases with carbon chainlength
- Insoluble (nonpolar)
Draw a sigma bond and state which molecules they are present in.
- Present in both alkanes and alkenes
Draw a pi bond and state which molecules they are present in.
- Present in alkene double bond only
State why alkanes are unreactive
- High bond enthalpy
- Low polarity of the σ bonds
Write the equations for the free radical substitution of ethane with chlorine
State the 2 limitations of free radical substitution
- Impurities are formed during termination that are not haloalkanes
- Further substitution may occur
Explain the affect of branching on MP/BP for hydrocarbons
- Boiling point increases with less branching of side groups
- Less branching gives more surface contact between molecules
- More surface contact gives stronger london forces which require more energy to break
Write the equation for the complete and incomplete combustion for alkanes (C3H8)
State the issue with carbon monoxide
- toxic and odourless gas that irreversible binds to haemoglobin
Explain why alkenes are more reactive than alkanes
- the bond enthalpy of the π bond is less than the bond enthaply for the σ bond
Draw sigma and pi bonds in alkenes
Explain the shape and bond angle of alkenes
-Trigonal planar
- 120°
- All three bonding pairs of electron regions repel equally
Explain why alkenes are reactive
- They have relatively low bond enthalpy of the π bond compared to sigma bond
- The π bond is broken first
State all the addition reactions of alkenes and their conditions
Write out the hydrogenation of alkenes (ethene)
Write out the halogenation of alkenes (ethene) with mechanism
Write out the hydration of alkenes (ethene)
Write out the addition of hydrogen halide of alkenes (ethene) with mechanism
Explain how the major product of addition reactions is determined
- the hydrogen atom of the H-X attaches to the carbon with the most hydrogens on it already
- because carbocations with more hydrogen atoms on are more stable
State the benefit of environmental polymers
- Reduces the need for finite resources
State a danger of combustion of polymers
- Releases toxic HCl fumes
