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Chapter 8 : Hydrocarbons - LCHS Physical
Science |
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Objectives: The learner will...
...identify and name hydrocarbons
and various functional groups
...convert between chemical and structural formula of various
hydrocarbons |
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Vocabulary:
hydrocarbon : covalently bonded
molecules made of Hydrogen and Carbon
functional group : other atoms that replace hydrogens in hydrocarbons
carboxyl : a functional group that turns a hydrocarbon into
an organic acid
hydroxyl : a functional group that turns a hydrocarbon into
an alcohol
structural formula : the use of element symbols and lines
to show the relative position of the atoms in a molecule |
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HYDROCARBONS
| Hydrocarbons are a group of covalently bonded molecules
that are predominately made of Hydrogen and
Carbon. Carbon has 4 electrons to share in the outer shell
and will bond with itself and other atoms. Carbon can share
1, 2 or 3 electrons with another carbon to form long chains,
branches and rings. Hydrogen often surrounds (or saturates)
this carbon backbone by sharing its 1 outer shell electron.
Other functional groups can replace hydrogens
to make new molecules with different behaviors. Functional
groups include: the halogens F, Cl, Br ; a hydroxide ion [OH]-
; and a carboxyl group [COOH]. |
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FORMULAS & NAMING
Naming hydrocarbons by observing their structure and using the table
below is a fairly straightforward and logical task. Count the number
of carbons in the structural formula (the symbol-stick
diagram) to determine the prefix. If all the carbons share
only one pair of electrons (single bond) then the
root is ane. Double bonded carbons have the
root ene and triple bonded carbons have the
root yne. For each additional bond between 2 carbons,
the carbons involved must each lose a hydrogen. A suffix
can be added if additional hydrogens have been replaced by certain
functional groups. Any hydrocarbon can be turned into an alcohol
by substituting a hydrogen with a hydroxide [OH]- ion. A
[COOH] functional group turns a hydrocarbon into an organic
acid. In this case an end carbon has 3 of its hydrogens replaced
with a double bonded oxygen atom =O and an -[OH], hence the [COOH].
Hydrogens can be replaced by other atoms to add even more variety.
| PREFIXES |
#C |
ROOT |
C:C bonding |
| meth |
1 |
ane (CnH2n+2) |
C-C single bond |
| eth |
2 |
ene (CnH2n) |
C=C double bond |
| prop |
3 |
yne (CnH2n-2) |
C=C triple bond |
| but |
4 |
SUFFIXES |
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| pent |
5 |
ol |
-[OH] alcohol |
| hex |
6 |
oic acid |
-[COOH] organic acid |
| hept |
7 |
Halogen Derivatives |
Halogen prefixes |
| oct |
8 |
fluor - F |
di - 2 |
| non |
9 |
chloro - Cl |
tri - 3 |
| dec |
10 |
bromo - Br |
tetra - 4 |
See the examples below to learn the relationships between naming,
the chemical formula and the structural formula.
| NAME |
Chemical
Formula |
Structural
Formula |
NAME |
Chemical
Formula |
Structural
Formula |
| propane |
C3H8 |
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H |
H |
H |
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| H |
-C- |
C |
-C- |
H |
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H |
H |
H |
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propene |
C3H6 |
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H |
H |
H |
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| H |
-C= |
C |
-C- |
H |
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H |
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| propyne |
C3H4 |
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propynol |
C3H3[OH] |
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| propynoic
acid |
C2H[COOH] |
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dibromo propanol |
Br2C3H5[OH] |
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Br |
H |
H |
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| H |
-C- |
C |
-C- |
[OH] |
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Br |
H |
H |
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| For an interactive viewing of 3-D molecular models
click a selection below |
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ISOMERS
| The formula for butane is C4H10.
The diagram at the right just shows the carbon chain. Notice
that the carbons can be arranged structurally in 2 different
ways yet still have the same chemical formula. These are
called isomers. The more carbons involved in the hydrocarbon,
the more possible arrangements exist for that molecules isomers.
The molecule at the bottom is called isobutane. |
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ISOMER
LAB LINK
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| Practice: |
Help: |
PB1
Write the formula for heptane
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5 C
single bonds |
PB2
Write the formula for octene
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8 C
double bond |
PB3
Write the formula for pentyne
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5 C
triple bond |
PB4
Write the formula for octanoic acid
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7
C + 1 in COOH
single bond |
PB5
Write the formula for difluorohexyne
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6 C, 2 F
triple bond |
PB6
Write the name for c6h14
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(see chart) |
PB7
Write the name for c4h8
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(see chart)
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PB8
Write the name for c6h10
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(see chart) |
PB9
Write the name for c6h13oh
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(see chart) |
PB10
Write the name for c10h19cl3
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(see chart) |
answer bank:
c5h8
hexyne
c7h16
hexanol |
c7h15cooh
c6h8f2
trichlorodecane |
butene
hexane
c8h16 |
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Scientist Spotlight:
Marie
Curie 1867-1924 Working with her husband, Pierre, she showed
thorium, as well as uranium to be radioactive, and demonstrated that
the radioactivity of a substance was proportional to the quantity
of radioactive material present.
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Resources (Study Links/Study Tips/Reading Lists)
ISOMER
LAB LINK
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Chapter 8 : Hydrocarbons - LCHS Physical
Science |
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