Module 4.1- organic compounds Flashcards
whats the general formula
an algebraic formula that can describe any member of a family of compounds e.g. CnH2n+2
whats the empirical formula
the simplest ratio of atoms of each element in a compound e.g CH3
whats the molecular formula
the number pf atoms of each element in a molecule with the functional groups indicated e.g. C4H9OH
whats the structural formula
shows the atoms of carbon by carbon with the attached hydrogens and functional group e.g CH3CH3CH2OH
whats the displayed formula
shows how all the atoms are arranged and all the bonds between them e.g H H
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H-C-C-H
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H H
whats the skeletal formula
shows the bonds of the carbon skeleton with any functional group e.g. /\/\/\/
what are aliphatic compounds
carbon atoms are joined together as straight chains or branched chains
what are alicyclic compounds
carbon atoms are joined together in a ring structure but not aromatic
what are aromatic compounds
at least one benzene ring in the structure ⬡
stem for a chain with 1 carbon
meth-
stem for a chain with 2 carbons
eth-
stem for a chain with 3 carbons
prop-
stem for a chain with 4 carbons
but-
stem for a chain with 5 carbons
pent-
stem for a chain with 6 carbons
hex-
stem for a chain with 7 carbons
hept-
stem for a chain with 8 carbons
oct-
stem for a chain with 9 carbons
non-
stem for a chain with 10 carbons
dec-
alkanes functional group
c-c
alkenes functional group
c=c
alcohols functional group & suffix
-oh & -ol
halogen alkanes prefix and suffix
halo (e.g chloro) & -ane
aldehydes functional group prefix and suffix
O
||
-C-H
oxo-
-al
ketones functional group prefix and suffix
O
||
C-C-C
keto/oxo-
-one
esters functional group prefix and suffix
O
||
-C-O-C
alkoxy carbonyl-
-oatecarboxylic acid functional group prefix and suffix
O || C-OH carboxy- -oic acid
amine functional group prefix and suffix
-NH2
Amino-
-amine
amide functional group prefix and suffix
O || C-NH2 amido- -amide
whats a homologous series
a series of organic compounds having the same functional group but which each successive member differing by CH2
what are alkanes
saturated hydrocarbons that have a single (sigma)
bond, they are part of the same homologous series.
whats a sigma bond
the overlap of orbitals between two atoms
why do straight chains have higher boiling points than isomers of itself
- straight chains can get closer together
- straight chains have more surface contact between molecules (not surface area) giving more induced dipole dipole forces.
- these require more energy to break so bp is higher
what forces act between hydrocarbons
London forces
complete combustion of alkanes, methane+ oxygen
methane + oxygen—> carbon dioxide + water
incomplete combustion of alkanes, methane+ oxygen
methane + oxygen—-> carbon monoxide + water + carbon
why are alkanes not very reactive
- they have a high bond enthalpy (strong bonds)
- very low polarity of sigma bonds present ( aren’t very polar)
what are isomers
molecules with the same molecular/chemical formula but different displayed/ structural formula
what are the two types of isomers
structural isomers and stereoisomers
what are structural isomers
-same molecular formula, different structural formula
what are stereoisomers
-have the same structural formula but different arrangement of atoms in place
what are the 3 isomers of pentane ( including pentane)
pentane
2-methylbutane
2,2-dimethylpropane
what are position isomers
where functional groups can be in different positions on the carbon carbon chain resulting in isomers
name all the position isomers for 1,1-dichloropropane
1,1-dichloropropane
1,2-dichloropropane
1,3-dichloropropane
2,2-dichloropropane
breaking covalent bonds, unequal splitting, what does it produce and what is it known as?
- produces ions
- known as heterolysis or heterolytic fission
breaking covalent bonds, equal splitting, what does it produce and what is it known as?
- produces radicals (now more reactive)
- known as homolysis or homolytic fission
what are radicals
highly reactive species with one or more unpaired electron.
halogenalkanes from alkanes general equation
CnH2n+2 + X2 —> CnH2n+1X + HX
whats a functional group
a group of atoms responsible for the characteristic reactions of a compound.
plastics can be disposed in 6 ways…
- landfill
- combustion
- electricity generation
- reuse
- recycle
- organic feedstock
recycling negatives:
- costly
- plastics have to be sorted
- requires high technology
- labour intensive
how d photodegradable plastics break down
break down chemically using energy with wavelengths simmilar to light . once the process begins it cant be stopped
organic feedstock explanation
plastics are separated and broken down into small organic molecules through a series of reactions. the molecules can then be used to produce plastics in other industries
negatives of photodegradable polymers
may not be exposed to sufficient light
when halogens react with alkanes what do they form
haloalkanes
when halogens react with alkanes, what is tis type of reaction called
free radical substitution
what is substituted during free radical substitution
a hydrogen atom is replaced by (substituted by) chlorine or bromine
halogens+alkanes: write the overall equation for chlorine reacting with bromine
CH4 + Cl2 –> CH3Cl + HCl
write an overall equation to show the formation of bromomethane from methane and bromine
CH4 + Br2 –> CH3Br + HBr
when is a Pi bond formed
formed by the sideways overlap of two adjacent p orbitals.
when are sigma bonds formed
when two s orbitals overlap
talk about the strength of sigma bonds
the high electron density between the nuclei means there is a strong electrostatic attraction between the nuclei and shared pair of electrons- this means that there is a high bond enthalpy- they are the strongest type of bonds. (the C-C and C-H) bonds in alkanes are all sigma bonds
talk about the strength of Pi bonds
much weaker than sigma bonds because the electron density is spread out above and below the nuclei. this means that the electrostatic attraction between the nuclei and shared pair of electrons is weaker, so Pi bonds have a relatively low bond enthalpy.
why are alkenes much more reactive than alkanes (lengthy)
1) Alkanes only contain C-C and C-H sigma bonds= high bond enthalpy= difficult to break, the bonds are also non-polar so they don’t attract nucleophiles or electrophiles thus they dont react easily
2) Alkenes are more reactive than alkanes because the C=C bond contains both a sigma bond and a Pi bond.
3) The C=C double bond contains 4 electrons so it sticks out above and below the rest of the molecule . These two factors means the Pi bond is likely to be attacked by electrophiles, the low bond enthalpy of the Pi bond also contributes to the reactivity of alkenes
4) because the double bond is so reactive, alkenes are handy starting points for making other organic compounds and for making petrochemicals
what does the restricted rotation of the C=C bonds cause alkenes to form
to form stereoisomers
what is stereoisomerism and talk about the types of stereoisomerism
- stereoisomers occur when two double bonded carbon atoms each have two different atoms or groups attached to them
- E/Z isomerism is a type of stereoisomerism
- E/Z isomers can sometimes be called cis/trans isomers
how do u work out the priority of E/Z isomers
- firstly split down vertically on the C=C bond and look a the split off sections individually to find the atom with the larger atomic number as its given higher priority.
why is ethene said to be planar
carbon atoms on a C=C double bond and the atoms bonded to these carbons all lie in the same place, they’re planar
E/Z isomerism: what do u do when the atoms directly bonded to the carbon are the same when trying to figure out priority
-you need to look further along the chain (look at the next atom in the group to work out which has a higher priority)
cis/trans: what does cis mean
the same groups on the same side of the double bond
cis/trans: what does trans mean
the same groups are on the opposite side of the double bond
whats it called when halogens react with alkenes
electrophilic addition, electrophile (electron pair acceptors)
