Chapter 8.1 Alkanes Flashcards
Carbon forms more compounds than all other elements combined because of its properties?
What are they?
- has 4 VALENCE ELECTRONS so it has the potential to from covalent bonds with four different atoms
- Carbon atoms can form strong covalent bonds with other carbon atoms.
- The covalent bonds formed can be a combination of single, double or triple bonds.
Example of Carbon based compounds
- Caffeine
- petrol
- pesticides
- plastics
- artificial flavours
What is crude oil?
Fossil fuel - low in density (
*making able to migrate upwards through the crust where it often became trapped beneath impervious (unable to pass through) rock. Accumulation of oil and gas under the rock creates an oil felid.
Over millions of years dead Organic material was affected by high pressures and temperature (buried under the earths’s crust via sediment),causing the oil and fats to be converted into hydrocarbon.
How is crude oil used?
Not used in raw state
Transported from oil fields to oil refineries where it undergoes fractional distillation in a fraction given tower.
In this process crude oil is separated into its various components or fractions.
Each fraction is made up of a range of hydrocarbons with similar boiling points and hence molecular masses.
The compounds of crude oil that are obtained by fractional distillation are used for a wide range of purposes but now 90% is used for fuels.
Further processing of crude oil fractions is needed to these components even more useful.
Heavier fractions undergo a process called CRACKING,
This process breaks the larger hydrocarbon molecules into smaller molecules using HEAT and a catalyst.
The smaller molecules and especially those with carbon-carbon double bonds (called alkenes) are needed by the petrochemical industry.
What is a hydrocarbon? Which is the simplest one?
Hydrocarbons are an organic compound composed of only carbon and hydrogen.
Simplest form is Methane - CH4; one carbon atoms is covalent bonded to 4 hydrogen atoms to form a molecule.
What does saturated mean?
Containing the greatest possible number of hydrogen atoms, without carbon-carbon double/triple bonds
What is a homologous series?
A series of molecules in which each member differs by -CH2- from the previous members
Eg, each member of the alkenes series differs from the previous member by a -CH2 - unit.
What are the characteristics of compounds that are members of the same homologous series?
- similar structure
- a pattern to their physical properties
- similar chemical properties
- the same general formula
What is an Alkane?
Alkanes are hydrocarbons that contain only single bonds.
- all Carbon-Carbon bonds are single covalent bonds
Alkane chemical formula?
CnC2n+2
What are the properties of an Alkane?
- Saturated
- Naming ends with -and
- Formula - CnH2n+2
- Non polar
Why are Alkanes non- polar?
Alkanes only have weak forces between molecules because they are non-polar.
As the number of carbons and the size of the molecules increase within its homologous series, the strength of the these forces increases so the melting and boiling points of alkanes increases
What happens as homologous series increases in size?
- Bonds around each carbon atom adopts a tetrahedral shape
- boiling and melting points increase
List Stem/ parent names in order (conventions of naming a hydrocarbon)
- Meth-
- Eth-
- Prop-
- But-
- Pent-
- Hex-
- Hept-
- Oct-
- Non-
- Dec-