Basic concepts of organic chemistry Flashcards
Saturated
Containing single bonds only
Unsaturated
Containing a multiple carbon-carbon bond
Homologous series
A family of compounds with similar chemical properties, whose successive members differ by the addition of a —CH2— group
Functional group
The part of the organic molecule largely responsible for the molecule’s chemical properties
Aliphatic
Carbon atoms are joined to each other in unbranched (straight) or branched chains, or non-aromatic rings
Alicyclic
Carbon atoms are joined to each other in ring (cyclic) structures, with or without branches
Aromatic
Some or all of the carbon atoms are found in a benzene ring
Molecular formula
Shows the number and type of atoms of each element present in a molecule
Empirical formula
Simplest whole number ratio of the atoms of each element present in a compound
General formula
Simplest algebraic formula for any member of a homologous series
Displayed formula
Shows the relative positioning of all the atoms in a molecule and the bonds between them
Structural formula
Shows clearly which groups are bonded together e.g. CH3(CH2)2CH3
Skeletal formula
Simplified organic formula, where all the Cs and Hs are removed and only the bonds between Cs and any functional groups are shown
Structural isomerism
Compounds with the same molecular formula but different structural formulae
Homolytic fission
Each of the bonded atoms take one of the shared pair of electrons from the bond, forming two radicals with an unpaired electron; represented using fish hook arrows
Heterolytic fission
One of the bonded atoms takes both of the electrons from the bond, forming one +ve and one -ve ion; represented using curly arrows
Addition reaction
Two reactants join together to form one product
Substitution reaction
An atom or group of atoms is replaced by a different atom or group of atoms; 2 reactants –> 2 products
Elimination reaction
Involves the removal of a small molecule from a larger one; 1 reactant –> 2 products
Stereoisomerism
Have the same structural formula but a different arrangements of atoms in space
E/Z isomerism
Arises because rotation about the double bond is restricted and the groups attaches to each carbon atom are therefore fixed relative to each other (caused by pi-bond’s electron density above and below the plane of the sigma-bond)
Requires - a C=C bond and different groups attached to each of these Cs
Cis-trans isomerism
Special case of E/Z isomerism, where one of the attached groups on each carbon atom of the double bond must be the same
Effect of chain length on boiling points of alkanes
London forces act between molecules in close surface contact, so as chain length increase, surface area increases, allowing more surface contact; London forces will be larger
Effect of branching on boiling point
Branched isomers have lower boiling points because branching means there are fewer surface points of contact between molecules (branches get in the way and prevent the molecules getting as close together as possible), resulting in fewer London forces
Disposing of waste polymers
Lack of reactivity makes polymers suitable for storing food and chemicals, but also hard to dispose because they are non-biodegradable, causing environmental effects (killing marine life)
Recycling
Reduces environmental impact by conserving fossil fuels and decreasing waste going to landfill.
Have to separate polymers, chop into flakes, wash, dry, then melt. Cut into pellets to use.
PVC recycling
Hazardous due to high chlorine content (releases toxic gases when burnt). Used to grind before solvents were introduced, so PVC is dissolved, then recovered by precipitation.
Using waste polymers as fuel
Polymers that are difficult to recycle can be incinerated to heat homes, etc. (release lots of energy due to their origin from natural gas and crude oil).
Feedstock recycling
Chemical and thermal processes that can reclaim monomers, gases or oils from waste polymers. Able to handle unsorted and unwashed polymers.
Biodegradable polymers
Polymers made from plant starch, cellulose, plant oils and proteins can be broken down by microorganisms into water, carbon dioxide, etc.
Photodegradable polymers
Contain bonds that are weakened by absorbing light to start the degradation.
