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whereas the first chapter dealt with topics that were general in nature but
the kind of things that we will need for organic chemistry, it's chapter two here
when we really start focusing on organic chemistry itself
and our starting point is the class of compounds considered to be the simplest
in the world of organic chemistry
they are a type of hydrocarbon called alkanes
hydrocarbons only contain carbon and hydrogen and of compounds like that
alkanes are the starting point
and so that a lot of this chapter deals with
being able to represent these alkanes
using different structural formulas and also being able to put names
with them
because there is a special naming system in organic chemistry
and we are going to start learning some of the rules in chapter two
and will use them throughout the course
this barrel is here on the slide because the source of hydrocarbons in
general
are fossil fuels
but for organic chemists instead of just burning them for energy they use them to
create all kinds of different materials from plastics to
pharmaceuticals
and they are considered to be the starting point for a wide variety of of
materials made in organic chemistry
and so we want to get familiar with a few of those
there are at least three different types of hydrocarbons alkanes that's the focus
of chapter two
and his will see just like the word alkanes end in -ane
particular examples of alkanes have that suffix in their name
that's coming up later
as it says here alkanes identified by having only single bonds between the
carbons
later in chapters five and six we'll deal with alkenes, with the -ene
suffix
and as it says here their distinguishing characteristic is the double bond
between carbons
alkynes-- that's how you pronounce that last one--those are dealt with
good bit in chapter nine. we won't get to that chapter in this course if
you are around for chemistry 212
that's when we talk about alkynes in great depth
but all of those are mentioned in chapter two and
they can be distinguished by the difference in those suffixes
and in terms of their structures the difference between a single bond, double
bond, or triple bond
as i say were mostly dealing with single bonds
those types of hydrocarbons in this chapter
and you'll need to be familiar with the names of the first ten of those because
they form the basis of all the other names that we're going to see.
here's the first four of those. methane is the simplest
organic compound
is the simplest hydrocarbon
and it's only got the one carbon
ethane is the two-carbon alkane, propane is for three carbons, butane
for four
the molecular formulas here in the second column don't tell you much
about how things are connected
structural formulas are more informative and so we're going to be using
structural formulas
pretty much the whole semester
these formulas in the third column illustrate that each carbon is bonded
to just the number of hydrogens it needs to satisfy the octet rule that we saw in
the last chapter
so the structural formulas can sometimes show every one of those bonds
to every carbon to
really give the detail of what is connected to what
more often we're going to use these condensed structural formulas
where it's assumed that the carbons are all connected one after the other
and after each carbon, it indicates how many hydrogens it has, and it will have the
special number of hydrogens needed to give each carbon exactly four bonds.
all alkanes follow that rule
so these names on the left in the
***-, the eth-, the prop- , but-, the first part of the names are associated with how many
carbons
the a_n_e_ tells us that all the carbons only making single bonds
and in the next little with video will meet some more members of the
alkane family