Download elements of chemistry unit

MR. SURRETTE
VAN NUYS HIGH SCHOOL
CHAPTER 9: ORGANIC COMPOUNDS
CLASS NOTES
THE CARBON ATOM
Of all the elements on the periodic table, carbon forms the strongest bonds, and bonds to the most kinds
of atoms. Also, multiple carbon atoms link together with single, double, and triple bonds. The number
of carbon-based compounds is many times greater than the sum of all other compounds.
ORGANIC CHEMISTRY
All life is based on carbon compounds, so the study of carbon is called organic chemistry. However,
all “organic compounds” are not derived from plants and animals.
STRUCTUAL FORMULAS
Structural formulas show the arrangement of atoms in molecules or polyatomic ions. Each dash
between two atoms represents a pair of shared electrons.
STRUCTUAL FORMULA EXAMPLE
The following is the structural formula for propane, one of the simplest organic compounds:
SINGLE BONDS
Atoms that share two electrons form single bonds. On structural diagrams, single bonds are represented
by single dashes between atoms.
DOUBLE BONDS
Atoms that share four electrons form double bonds. On structural diagrams, double bonds are
represented by double dashes between atoms.
TRIPLE BONDS
Atoms that share six electrons form triple bonds. On structural diagrams, triple bonds are represented
by triple dashes between atoms.
CARBON BONDING
Carbon atoms have hour bonding electrons. The means, on most structural diagrams, C atoms are
surrounded by four dashes.
HYDROGEN BONDING
Hydrogen atoms only have a single electron. This means, on structural diagrams, H atoms have only
one dash connecting them to other atoms.
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MR. SURRETTE
VAN NUYS HIGH SCHOOL
MOLECULAR FORMULAS
Molecular formulas show the actual number and kinds of atoms present in a molecule.
PROPANE
The structural formula for propane shows 3 axial carbon atoms and 8 peripheral hydrogen atoms. The
molecular formula of propane is C3H8. Molecular formulas do not provide as much information as
structural formulas. In particular, they do not show how atoms are connected.
ISOMERS
Several molecules with the same composition but different structures are called isomers.
ISOMER EXAMPLE
Compare two different compounds that have 4 linked carbon atoms.
ISOMERS OF C4H10
C4H10
Although the two compounds above have the same molecular formula, their structural formulas are
different in the way that the 4 carbons are assembled. As seen below, structure is just as essential as
composition to understanding organic chemistry.
C4H10 ISOMERS
The two varieties of C4H10 shown are isomers. In other words, they have the same composition but
different structures. Structure affects both physical properties and chemical reactivity of isomers. For
example, butane boils at -1 oC and isobutane boils at -12 oC.
CONDENSED STRUCTURAL FORMULAS
Condensed structural formulas leave out some bonds and/or atoms within compounds. The presence
of the atoms or bonds is understood. Chemists frequently write condensed structural formulas to omit
carbon-hydrogen bonds.
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MR. SURRETTE
VAN NUYS HIGH SCHOOL
CONDENSED STRUCTURAL FORMULAS
HYDROCARBONS
An infinite variety of compounds can be made using only carbon and hydrogen atoms. These
compounds are called hydrocarbons. Hydrocarbons are of prime economic importance because they
include petroleum and natural gas.
ALKANES
Propane, butane, and isobutane are all hydrocarbons that contain only single covalent bonds between
carbon atoms. These hydrocarbons lack double bonds, triple bonds, and ring structures. As a whole,
these types of hydrocarbons are called alkanes.
THE SIX SIMPLEST ALKANES
ALKENES
Alkenes are hydrocarbons that contain at least one double bond between carbons. The simplest alkene
is ethylene, C2H4,
ETHYLENE
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MR. SURRETTE
VAN NUYS HIGH SCHOOL
ALKYNES
Alkynes are hydrocarbons that contain a triple bond between carbons. The simplest compound in this
class is acetylene, C2H2.
ACETYLENE
RING STRUCTURES
Long chains of carbons can loop around and form closed ring structures. For example, examine the
structure of hexane.
HEXANE
RING STRUCTURES
Remove 2 hydrogens on the ends of hexane, and you get cyclohexane.
CYCLOHEXANE
COMPOUNDS WITH ADDITIONAL ELEMENTS
Although all organic compounds contain carbon, and almost all of them contain hydrogen, most of them
contain other elements as well. The most common extra elements in organic compounds are oxygen,
nitrogen, sulfur, and the halogens (Group 17).
HALOGENS
Halogens resemble hydrogen because they form single covalent bonds. As a result, halogen atoms can
replace any hydrogen atom in hydrocarbons.
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MR. SURRETTE
VAN NUYS HIGH SCHOOL
METHANE AND TWO DERIVATIVES
ALKYL HALIDES
When halogens replace the hydrogen atoms in hydrocarbons, they form compounds called alkyl halides.
Alkyl halides include fluorine, chlorine, bromine, iodine, or any combination of these elements.
FUNCTIONAL GROUPS
Functional groups are specific arrangements of atoms in an organic compound that undergo
characteristic chemical reactions. Most organic chemistry is functional-group chemistry. As a matter of
fact, organic compounds are even classified according to their functional groups.
COMMON FUNCTIONAL GROUPS
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