Alkanes Flashcards
what are alkanes?
alkanes are hydrocarbons that fit the general formula CnH2n+2
what are alkanes made up of?
they are made of simple molecules containing C and H atoms held together by covalent bonds
what does the name of the alkane show?
- the start of the name shows how many carbon atoms it has
- the end of the name is ‘-ane’ to show its an alkane
what is the formula of methane?
CH4
how many carbon atoms does methane have?
1
what is the formula of ethane?
C2H6
how many carbon atoms does ethane have?
2
what is the formula of propane?
C3H8
how many carbon atoms has propane got?
3
what is the formula of butane?
C4H10
how many carbon atoms does butane have?
4
what is the formula of pentane?
C5H12
how many carbon atoms does pentane have?
5
what are the names of alkanes after the first five?
the names follow the 2D shapes: hexane, heptane, octane etc.
what are the four different formulas of alkanes?
- displayed formula
- structural formula
- molecular formula
- empirical formula
what is the displayed formula of an alkane?
a diagram showing the positions of every atom and every bond (C and H’s)
what is the structural formula of an alkane?
this shows the structure of the molecule in one line, read from left to right like a word
eg. CH3CH2CH2CH3
what is the molecular formula of an alkane?
this only shows how many carbon and hydrogen atoms there are
e.g. C4H10
what is the empirical formula of an alkane?
this only shows the simplest whole-number ratio of carbon to hydrogen
e.g. C2H5
what is a homologous series?
alkanes are a homologous series of organic molecules - this means they are a family of molecules
what do alkanes all have?
- similar chemical reactions
- trends in physical properties (e.g. boiling points, viscosity or colour)
- the same general formula
how many series of homologous are there in the IGSCE course?
five:
- alkenes
- alcohols
- carboxylic acids
- esters
- alkanes
what are isomers?
isomers are molecules with the same molecular formula but different structural formulae
how many isomers does C4H10 have?
two