test 2 - hydrocarbons (ch 8/11) Flashcards
what is an alkane?
an aliphatic - hydrocarbon that contain only single bonds - this means they are saturated (no space for new bond)
properties of carbon that allow it to the basis of so many things?
it has 4 valence electrons, allowing it to form 4 bonds with other non-metals - it can form single, double and triple bonds into varied lengths and shapes
examples of carbon based molecules?
caffeine, plastic and petrol
what is crude oil?
produced by the effects of heat and pressure on dead organisms in earth’s crust - it is a source of carbon compounds
how is crude oil made?
when the dead matter was pressured in the earth’s crust, the oils and fats from these organic materials turned into hydrocarbons
properties of crude oil?
low density - migrates up towards crust
properties of methane?
colourless, odourless gas, very flammable - main component of natural gas
properties of compounds of the same homologous series?
- similar structure
- a pattern to their physical properties
- similar chemical properties
- same general formula
how strong are the forces in alkanes?
they have weak force between the molecules as they are non-polar. bigger molecules are stronger with higher m/b points
alkane general formula?
C(n)H(2n +2)
what is a structural isomer in alkanes?
when alkanes have more than 4 carbon atoms (butane and above) they can have more than one possible structure
example of an alkane structural isomer?
with a side chain. for example, butane has a structural isomer called 2-methyl-propane (reference - pg.165)
how to write -alkyl groups (side chains) in condensed structure formula?
use brackets (reference pg. 168 figure 8.1.8)
do the chemical properties change for a structural isomer?
yes. the boiling and melting points differ
IUPAC system of naming alkane
name the following examples with this system:
- CH3-CH(CH3)-CH(CH3)-CH3
- CH3-CH2-CH(CH3)-CH2-CH3
answer to q1 is 2,3-dimethylbutane
answer to q2 is 3-methylpentane
- make sure it is a single bond
- longest chain of carbon? (methane, ethane, propane, butane)
- identify side chains (what is it? methyl, ethyl etc. - if more than one TYPE of side chain, name in alphabetical order)
- where is the side chain located? (lowest number)
- how many of the SAME side chain are there? (e.g. 4-dimethyl)
what is an alkene?
an aliphatic - hydrocarbon with at least one double bond - these are unsaturated - meaning they can break the bonds to form new bonds
alkenes reactivity relative to alkane?
alkenes are more reactive, as they can form addition reactions (by breaking bonds)
General formula for alkene?
C(n)H(2n)
properties of alkenes?
non polar (do not dissolve in water)
structural isomers in alkene?
when there are more than three carbon atoms a structural isomer will occur. these are numbered from the lowest number to the double bond
what are geometric isomers in alkenes? (cis/trans)
joined in same order, but different arrangement. occurs because of the atoms around a double bond cannot rotate (they can in a single bond)
how do cis isomers look?
the same group is located on the same side of the double bond (horizontal symmetry wise)
how do trans isomers look?
the same group is located on the OPPOSITE side of the double bond (and only OPPOSITE side)
IUPAC system of naming an alkene
name the following using this system:
- CH3-CH2-CH=CH2
- CH3-CH2-CH=CH-CH3
answer of q1 is but-1-ene
answer of q2 is pent-2-ene
- identify longest carbon chain (must include double bond)
- number carbon atoms in a way that will result in the smallest number for the double bond
- where is the double bond located? (but-1-ene)
- side chain (what are they)
- where are the side chains located (double bond precedes anything else - number from where double bond is lowest number)
- how many side chains (di-, tri-)
