Transcript Topic 10.1 Organic Chemistry Introduction

10.1 Introduction
Assessment Objectives
 10.1.1 Describe the features of a homologous
series.
 10.1.2 Predict and explain the trends in boiling points
of members of a homologous series.
 10.1.3 Distinguish between empirical, molecular
and structural formulas.
 10.1.4 Describe structural isomers as compounds
with the same molecular formula but with
different arrangements of atoms.
References
 Moodle
 Textbook
 Workbook
 Videos
Key Terms
 Hydrocarbon
 Homologous Series
 Alkane/alkene/alkyne
 Functional Group
Assessment Objective
 10.1.1 Describe the features of a
homologous series.
Firstly……......
 Lets look at some terms………….
Hydrocarbon
 Hydrocarbons are organic compounds that contain
only hydrogen and carbon.
 Types of hydrocarbons include:
 Alkanes
 Alkenes
 Alkynes
 Aromatic
Functional Groups
 As has already been indicated, alkanes are
relatively unreactive.
 For an organic molecule to be reactive it
needs something additional.
 A site of reactivity in an organic molecule is
called a functional group.
 C=C double is a functional group.
 Other functional groups contain elements
other than C or H, notably O, N and Cl.
LEARN THESE !!!!!!!!!!!
Homologous Series
 Homologous series is a set of compounds whose
components differ by a single repeating functional
group.
 In the case of (straight chain) ALKANES, their
general formula is:

CnH2n+2
An Example of an Homologous Series
Assessment Objective
 10.1.2 Predict and explain the trends in boiling
points of members of a homologous series.
Hypothesis
What do you
predict will
happen to the
boiling point as
you increase the
size of the
molecule?
Why??
Activity
 Worksheet.
In a homologous series there is a gradual increase in boiling
points as the # of carbon atoms increases.
Cross reference with 4.3.
Melting Points and Boiling Points
 Boiling points of unbranched
alkanes increase smoothly
with number of carbons
 Melting points increase in an
alternating pattern
according to whether the
number of carbon atoms in
the chain is even or odd
Assessment Objective
 10.1.3 Distinguish between empirical, molecular
and structural formulas.
Structural Formula
Note Each
carbon has
4 bonds
This is a full
structural or
displayed formula.
All the bonds are
shown including all
the hydrogen atoms
This is a form of a condensed structural formula
Molecular Formula
C6H12 is a molecular formula. It does not give
much information as this could be any one of
several different compounds
Empirical Formula
 This is the simplest whole number ratio
 For example if the molecular formula of glucose is
C6H12O6
 Then the empirical formula is CH2O
 This is the empirical formula for many carbohydrates
General Formula
 This are used for homologous series
 The alkanes
CnH2n+2
 The alkenes
CnH2n
 The alkanols or alcohols CnH2n+1OH
Assessment Objective
 10.1.4 Describe structural isomers as compounds
with the same molecular formula but with
different arrangements of atoms.
Activity
 How many different ways can you draw the
structural formula of butane?
 General formula CnH2n+2
 Molecular Formula C4H10
 What about pentane?
Activity
 Molecular Modeling Kit
The number
of isomers
possible for
a given
molecular
formula
increases
rapidly with
the number
of carbons
Structural Isomers
 Compounds with the same molecular formula
but with different arrangements of atoms.
 These isomers will have different physical
properties.
 So how do we name them (and distinguish
between them)???????
Assessment Objectives
 10.1.5 Deduce structural formulas for the isomers
of the non-cyclic ALKANES up to C6.
 10.1.6 Apply IUPAC rules for naming the isomers
of the non-cyclic alkanes up to C6.
Naming Organic Compounds
 Originally compounds were named based on their
source or use
 Many organic compounds were given common name
which are still in use
 However many ambiguities resulted
 With the large number of organic compounds, a
method for systematically naming them is very
important.
IUPAC Names
 The International Union of Pure and Applied
Chemists (IUPAC) developed a system for naming
organic compounds.
 This system eliminated many of the ambiguities
that plagued earlier naming systems.
 Common names for many substances are still
widely used
Naming Organic Molecules
 A series of prefixes are used to designate the
number of carbon atoms in a carbon chain.
 meth C1
 eth
 prop
 but
 pent
C2
C3
C4
C5
hex
hept
oct
non
dec
C6
C7
C8
C9
C10
Naming Straight Chain Alkanes
Naming Branched Chain Alkanes
1. Locate the longest continuous chain of carbons; this is the
parent chain and determines the parent name.
2. Number the longest chain beginning with the end of the chain
nearer the substituent
3. Designate the location of the substituent
Examples
4. When two or more substituents are present, give
each substituent a number corresponding to its
location on the longest chain
Examples
5. Substituents are listed
alphabetically.
When two or more substituents
are identical, use the prefixes
di-, tri-, tetra- etc.
Commas are used to separate
numbers from each other
The prefixes are used in
alphabetical prioritization
When two chains of equal length
compete to be parent, choose
the chain with the greatest
number of substituents
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Try These……….
Assessment Objectives
 10.1.7 Deduce structural formulas for the isomers
of the straight-chain alkenes up to C6.
 10.1.8 Apply IUPAC rules for naming the isomers
of the straight-chain alkenes up to C6.
 Alkenes are named by finding the longest chain
containing the double bond and changing the name
of the corresponding parent alkane from -ane to ene
 The compound is numbered to give one of the
alkene carbons the lowest number
 The double bond of a cylcoalkene must be in
position 1 and 2
 Please draw all the structural isomers (apart from
cyclic isomers) for C4H10, C5H12 and C6H14 and
name them.
Assessment Statement
 10.1.9 Deduce structural formulas for compounds
containing up to six carbon atoms with one of the
following functional groups: alcohol, aldehyde,
ketone, carboxylic acid and halide.
 10.1.10 Apply IUPAC rules for naming compounds
containing up to six carbon atoms with one of the
following functional groups: alcohol, aldehyde,
ketone, carboxylic acid and halide.
Activity
 Draw structural formula and name: …..
 CH3CH(OH)CH3
 CH2 (Cl)CH2CHO
 HCOOH
 CH3 (CH2)2OCH3
 CCl3COOH
 CH3CCl2CH(OH)CH2CH3
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Assessment Statement
 10.1.11 Identify the following functional groups
when present in structural formulas:
amino (NH2), benzene ring and esters (RCOOR).
You need to recognize the benzene structure in
structural formulas
This is the general layout
with a perfect hexagon. In
this particular diagram you
do not see the double
bonds.
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Two Lewis structures for the benzene ring.
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Shorthand notation for benzene rings.
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Some common mono-substituted benzene
molecules
Toluene, sometimes you see
this on marker pens ”contains
no toluene”
Has the condensed structural
formula C6H5CH3
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 Name each of the following
 CH3CH2NH2
 CH3COOCH2CH3
 C2H5COOCH3
 CH3NH2
 C3H8COOCH2CH3
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Naming esters
 The alcohol part of the name comes first and the
carboxylic part second
 For example CH3COOCH3 is made from CH3COOH
and CH3OH. i.e Ethanoic acid and methanol
 It’s name is Methyl ethanoate
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Assessment Statement
 10.1.12 Identify primary, secondary and tertiary
carbon atoms in alcohols and halogeno-alkanes.




Primary alcohols have –RCH2OH
Secondary alcohols have –R2CHOH
Tertiary have alcohols –R3COH
This means primary have 1 ‘different group attached,
we usually call this an R group.
 Secondary have 2 R groups and tertiary have 3 R
groups attached to the C next to the functional group

If two identical groups occur on the same side of the double bond the
compound is cis
If they are on opposite sides the compound is trans

Several alkenes have common names which are recognized by IUPAC

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