organic chemistry Flashcards
What is a hydrocarbon?
A hydrocarbon is a molecule made up of only hydrogen + carbon
why type of bonds do alkanes have?
single covalent bonds
what is the alkane formula
CnH2n+2
how many bonds can carbon form?
4 bonds
what is CH4 called ?
methane
what is a homologous series?
a group of hydrocarbons with a similar function group and therefore similar properties e.g alkAnes, alkEnes, alcOHOLS
what are the first 6 alkanes
1= methane 2= ethane 3=propane 4=butane 5=pentane 6=hexane
what is a structural isomer?
molecules that have the same molecular formula but a different structural formula i.e the order the atoms are connected to the chain is differnt.
the longer the hydrocarbon the_____ the surface area
bigger
the larger the surface area the______ the number of intermolecular forces.
higher
the greater the number of intermolecular forces the _____ the energy required to break them.
higher
the more energy required to break the intermolecular forces the ____ boiling point
higher
what type of bond is present in an alkene
a double bond
what is the general formula for an alkene ?
CnH2n
if the double bond was on the first carbon of an alkene with 4 carbons what would you name it?
but-1-ene
are alkanes saturated and why?
alkanes are saturated because every spare bond is attached to a hydrogen
are alkenes saturated and why?
alkenes unsaturated because they contain a double bond and therefore have less carbon atoms
what is a symmetric alkene?
semetric alkenes have the same groups on each side of a double bond
what is an asymmetric alkene
asymmetric alkenes have different groups on each side of the double bond.
what is a geometric isomer in an alkene ?
geometric isomers is where there are the same groups on each side of them double bond however they have a different arrangement.
- this is because the double bond does not rotate
- same structural formula
what is a cis geometric isomer ?
cis is where the alkene has matching groups on the same side of the bond (if you draw out the skeletal formula it makes a c shape)
what is a trans geometric formula?
trans is where the matching groups are on opposite sides of the bond
z
- together
‘zame zide’
E
separate
tetrahedral , area of electron density and angle
4 and 109.5 degrees
trigonal planar ,area of electron density and angle
3 and 120
linear ,area of electron density and angle
2 and 180
where are sigma bond found and what are they
they are found in alkanes (single bonds)
which is the strongest, sigma or pi bonds?
sigma bond because there is a greater overlap
which is shortest a double bond or a single bond
a single bond
electrophile
a molecule or atom which is attracted to a negative charge and can accept a lone pair of electrons to form a covalent bond
electrophilic addition
atoms or ions are added across the bond. no atoms are lost. this can happen because the carbon is double bonded
double bond opens up to allow a molecule to join on.
carbocation
ion with a positively charged carbon atom
polarised
when a molecule becomes positive at one end and negative at the other
curly arrow
shows the movement of an electron pair
what is a stable carbocation
a carbon cation which is attached to the most carbon atoms (has the most electrons donated)
what do alkyl groups do? (carbon groups)
they have an electron donating effect
electron configuration
1s, 2s, 2p, 3s, 3p, 4s, 3d
p orbitals
2px 2py 2pz
max electrons in s
2
max electrons p holds
6
max electrons d holds
10
Each hybrid orbital contains 2 electrons ready for bonding
true or false
true
Each hybrid orbital contains 2 electrons ready for bonding
true or false
false only 1
P orbitals that are not hybridised can overlap to form pi bonds
true or false
true
The number of hybrid orbitals formed is always 1 more than the number of orbitals used
true or false
false, the same number
The superscript in sp3 tells you the number of s orbitals used to make the hybrid orbital.
true or false
false the p orbitals
Carbons with 3 areas of electron density form linear shapes.
true or false
false trigonal planar
how many orbitals in a tetrahedral molecule
hybridisation
one of the s orbitals and three of the p orbitals combine to form four hybrid sp orbitals
making 4 sigma bonds
how many orbitals in a trigonal planar molecule
hybridisation
one of the s orbitals and two of the p orbitals combine to form three hybrid sp2 orbitals
creating 3 sigma bonds.
how many orbitals in a linear molecule
hybridisation
one of the s orbitals and one of the p orbitals combine to form 2 hybrid sp orbitals creating 2 sigma bonds
What are the prefixes for branched alkanes with a chain length of 1 - 4 carbons? Eg methyl, …
ethyl propyl butyl
What is a cycloalkane?
alkanes that have carbon atoms attached in a ring.
how do you test for an alkene ?
bromine water
What is electron pair repulsion theory?
The principle that electron pairs around a central atom tend to orient themselves as far apart as possible.
what are the three steps of a free radical ?
initiation, propagation, termination
conditions for free radical substitution
needs uv light to start the reaction (initiation stage)
What is heterolytic (bond) fission?
the breaking of a covalent bond in such a way that one atom gets both of the shared electrons
- creates a + and a - ion
What is homolytic (bond) fission?
Homolytic fission is where each atom of the bond keeps an electron each resulting in species called free radicals
What is a polymer?
a long chain molecule that is formed from small molecules linking together
What is the name for the mechanism for making polymers?
polymerization
What is cracking?
Cracking is a reaction in which larger saturated hydrocarbon molecules are broken down into smaller, more useful hydrocarbon molecules
What are the two types of cracking?
Catalytic cracking uses a temperature of approximately 550°C and a catalyst known as a zeolite which contains aluminium oxide and silicon oxide.
Steam cracking uses a higher temperature of over 800°C and no catalyst.
