hey everyone in this video we'll take a brief look at the naming conventions of hydrocarbons and these conventions will apply quite generally and widely to other types of organic compounds as well when we are naming hydrocarbons there are three things that we always consider and these are the functional group of the compound the number of carbon atoms in the compound and also if there are any types of substituents as was the position of these substituents we'll focus on the functional group first and when we say the word functional group we refer to specifically the type of hydrocarbon so is it an alkane alkene or alkyne and we are referring to alkenes and alkynes we also have to consider the position so the location of the double bonding alkene or the triple bond in alkynes the first step to naming hydrocarbons is to find the longest continuous carbon chain that contains the main or principal functional group and this is again where there's an alkane alkene or alkyne these two tables show you the prefixes and the suffixes that make up the name of a hydrocarbon the prefix is the first half of the hydrocompass name and this is determined by the number of carbon atoms in the longest chain of the molecule if the molecule only has one carbon then it will have a prefix of meth or myth in the case of an alkane this will be called a methane molecule if we have an alkane that contains eight consecutive carbon atoms this will have the name of octane where the prefix of oct stands for the a carbons the second table here shows you the suffix of the hydrocarbon name and this is strictly determined by the functional group of the hydrocarbon in the case of an alkane the name will end with a and e in the case of an alkene it will end with e and e and in the case of alkyne it will end with y and e so for a two carbon alkane it will be called ethane a two carbon alkene will be ethene and finally a two carbon alkyne will be called ethylene these are two more visual examples of how we name alkanes butane comes from two parts of the name butte refers to the fact that it has one two three four four consecutive carbon atoms in the molecule and because this molecule here only contains single covalent bonds this will be an alkane molecule hence the word butane this is a very similar molecule but this time around it contains one two three four five five consecutive carbon atoms and that's why the name here is given as pentane now let's have a look at how the name is slightly different when it comes to naming alkenes or alkynes this is a molecule of an alkene due to the presence of a double carbon carbon bond now this molecule here has one two three four four consecutive carbons and therefore the name is butane but there's something wrong with this name the mistake made in this name is that it is missing a number in front of the prefix that denotes the location of the double bond the diagrams here illustrates two different examples of a beauty molecule one butane is when the double bond is in the first possible position between the two carbon atoms and two butane is when a double bond moves one over into the second possible position so both of these molecules are butenes because they contain four consecutive carbon atoms and they are both alkenes but the number in front of the name differentiates the position of the double bond in the second step of naming we need to number the carbon chain such that the functional group so that is an alkene or alkyne receives the smallest number possible and after we prioritize a functional group location or position the substituents should also receive the smallest number possible so what do we mean by substituents this is a molecule that contains a substituent if we first find out the longest carbon chain one two three we know the name here will become propane because it's an alkane that contains three consecutive carbon atoms so how do we address the left over carbon atom that is not part of the three carbon chain this is what we call a substituent or branch that is not part of the main part of the carbon chain and this is where the word methyl in front of propane refers to the methyl here refers to the single carbon along the three hydrogen atoms that branches off the main part of the molecule a very similar idea applies to haloalkanes which are molecules that consist of the hydrocarbon part bound to halogen atoms in this case a bromine atom is found on the first of the three carbon atoms so the name here will be one bromo propane propane refers to the alkane molecule that contains three consecutive carbon atoms whereas the bromo prefix refers to the bromine atom that is attached to the first carbon of the carbon chain so what we've just gone through is the third step here name each substituent and indicate the position of the substituents this table summarizes some of the common substituents as well as the associated prefixes that you must use in the name to indicate the presence and the position of the substituents so we have methyl ethyl floral chloral bromo and iodo please take the time to review the names and structure of each of these six examples in your own time