Transcript Searching for Life in Our Solar System: Chapter 6

Organic Chemistry
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Introduction to organic chemistry
Principles of carbon chemistry
Principle of polymers
Hydrocarbons
Organic chemistry and biochemistry
Take Home Message
Organic Chemistry
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Introduction to organic chemistry
Principles of carbon chemistry
Principle of polymers
Hydrocarbons
Organic chemistry and biochemistry
Take Home Message
Elements of the Solar System:
Importance of Carbon
• 25 of 92 natural elements are known to be
essential to life on Earth
• Four of the above make up 96%!
– Carbon (C), Oxygen (O), Hydrogen (H) and
Nitrogen (N)
• Compare to solar abundance and discuss
relative to evolution of biochemistry in
origin of life
Elements of the Periodic Table
C
Relative Abundance of Elements in the Sun
12
Log of Relative
Abundance (Si)
H
10
He
8
O
C
Ne
6
Mg
Si
Ar
N
4
Na
2
Li
0
Ca
Al
P
Cl
K
Fe
B
Be
0
Fe
S
5
10
15
20
25
Atomic Number
30
35
40
45
Frequency of Carbon
• Carbon as a building block
– C is the 4th most common element in the solar system
– Probably the same frequency elsewhere in the Universe
• Conclusion: C is common throughout the Universe
and is likely to behave similarly (C and its tendency
to form covalent bonds) in most environments
Chemistry Subdivisions
• Organic Chemistry
– Chemistry of compounds in which C is the
principal element (biotic/living and abiotic/nonliving)
• Inorganic Chemistry
– Chemistry of all other elements
• Significance of C in chemistry
Organic Chemistry
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Introduction to organic chemistry
Principles of carbon chemistry
Principle of polymers
Hydrocarbons
Organic chemistry and biochemistry
Take Home Message
Principles of Carbon Chemistry: C’s
Atom
• C is unparalleled in its ability to form molecules that are
large, complex and diverse in structure
• Key is the C atom (protons, electrons, and quantum
mechanics)
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C has ____ electrons
Little tendency to gain or loose electrons (i.e., no ionic bonding)
Greater likelihood for electrons to be shared in covalent bonds
Possible covalent bonds per atom from __ to ___
Most common elements with which C bonds
• O, H, N and C (compare with prominence in living systems)
Principles of Carbon Chemistry:
Linkages among Carbon Atoms
• Linkages among C atoms form
macromolecules (define)
– Chains of C (methane and ethane)
– Branches of C
– Rings of C (e.g., benzene)
Principles of Carbon Chemistry:
Functional Groups
• Distinctive features of C macromolecules is a
function of two aspects of the molecules
– Carbon skeleton (chains, branches, rings)
• Chains, branches or rings
• Number of C atoms (2, 3, 4, etc.)
– Groups of atoms attached to carbon skeleton
• Called functional groups (some example)
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Hydroxyl (OH)
Amino (NH2)
Phosphate (P)
Total of five different functional groups
Organic Chemistry
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Introduction to organic chemistry
Principles of carbon chemistry
Principle of polymers
Hydrocarbons
Organic chemistry and biochemistry
Take Home message
Principle of Polymers: Introduction
• Principle of hierarchy theory and emergent
properties
• Small molecules joined together to form
large molecules up to 1,000’s of C atoms
• Macromolecules
• Infinite array of possible combinations, each
with its own unique chemistry
Principle of Polymers
• In living systems, polymers of C results in four major
classes of compounds that are of extreme importance
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Carbohydrates
Proteins
Nucleic acids
Lipids
• Linkages between C atoms via covalent bonds
• Calculating potential diversity of C polymers
– Analogy to alphabet (26 letters) and infinite ways to “create words”
– If 45 basic different C alphabet pieces, infinite ways to create
polymers of C
Organic Chemistry
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Introduction to organic chemistry
Principles of carbon chemistry
Principle of polymers
Hydrocarbons
Organic chemistry and biochemistry
Hydrocarbons
• Carbon compounds with only two elements:
– C and H
• C-C bonding via covalent bonds (nonpolar)
• Number of bonds
– 1, 2, 3, or 4
• Most simple compound is methane
H
H C H
H
Hydrocarbons: C to C Bonding
• C to C bond can be single bond (C-C)
H H
– Ethane H C-C H
H H
• C to C bond can be double bond (C = C)
H H
– Ethene C = C
H
H
• C to C bond can be triple bond (C = C)
– Ethyne H C = C H
Hydrocarbons: Groups
• Alkanes
– Single covalent bond between C atoms
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Methane (C1H4)
Ethane (C2H6)
Propane (C3H8)
Butane (C4H10)
Pentane (C5H12)
Octane (C__H18)
Decane (C__H22)
Pattern: CnH2n+2)
• Alkynes (triple bond C = C)
• Alkenes (double bond or C = C)
• Aromatics (rings or cyclic C atoms)
– Example (C6H6)
Hydrocarbons: Saturated and
Unsaturated Hydrocarbons
• Saturated hydrocarbons: maximum number of H
atoms bonded to C
– Ethane or
H H
H C - C H
H H
• Unsaturated hydrocarbons: anything else
H H
– Ethylene or C = C
H H
Organic Chemistry
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Introduction to organic chemistry
Principles of carbon chemistry
Principle of polymers
Hydrocarbons
Organic chemistry and biochemistry
Take Home Message
Organic Chemistry and
Biochemistry
• Keys:
– Structure of basic unit
– Polymer structure
– Functional group (e.g., OH, P or NH2)
• Types of C polymers for biotic systems
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Carbohydrates
Lipids
Proteins
Nucleic acids
Organic Chemistry and
Biochemistry: Monomers
• Carbohydrates
– Glucose or C6H12O6
– Functional unit: hydroxyl or OH-
• Proteins
– Amino acid
– Functional unit: amine or NH2
• Nucleic Acids
– Nucleotide or
– Functional units: organic N base, carbohydrate, and phosphate
• Lipids
– Fatty acids C16-18
– Functional unit: glycerol (3 OH- groups)
Organic Chemistry
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Introduction to organic chemistry
Principles of carbon chemistry
Principle of polymers
Hydrocarbons
Organic chemistry and biochemistry
Take Home Message
Take Home Message
• While the molecule of water is simple but exquisite and
unique in its chemical behavior, the C atom is unusual and
unique in its chemical behavior but for different reasons
– Covalent bonding
– Valence electrons
• Unusual behavior of C results in extreme array of simple to
very complex molecules as a function of
– Polymers
– Functional groups
• Life as we know it is hard to imagine without C behaving
as a polymer with covalent bonds to create carbohydrates,
proteins, nucleic acids and lipids (C polymers)
• Principle of hierarchy theory and emergent properties
Exam Coverage
• Text
– Chapter 9 (Atomic Structure; entire chapter)
– Chapter 10 (Elements & Periodic Table; entire chapter)
– Chapter 11 (Compounds and Chemical Change; entire chapter
excluding pages noted in lecture and posted on the www)
– Chapter 12 (Chemical Formulas; ONLY: pp 278-279; p 292 - Units
of Measurement)
– Chapter 13 (Water & Solutions; exclude pp 306-310 (electrolytes,
boiling point, and freezing point)
• Lecture Notes
– Atoms and Elements; Valence Electrons and Bonding; Water; and
Organic Chemistry
• Labs
– Physics: Electricity and Light
– NO OTHER LABS FOR THIS EXAM
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• No lecture, questions only