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Copyright © 2010 Pearson Education, Inc.
BASIC CHEMISTRY CH. 2
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Matter
• Definition: Anything that has mass and occupies space
• States of matter:
1. Solid—
2. Liquid—
3. Gas—
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Energy
• Definition: Capacity to do work or put matter into motion
• Types of energy:
• Kinetic—
• Potential—
• Electrical –
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Energy Form Conversions
• Energy may be converted from one form to another
• Conversion is inefficient
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Composition of Matter
• Elements
• Atoms
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Atomic Structure
• Neutrons
• Protons
• Electrons
Copyright © 2010 Pearson Education, Inc. Figure 2.1
Helium atom Helium atom
Nucleus Nucleus
Proton Neutron Electroncloud
Electron
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Identifying Elements
• Atoms of different elements contain different numbers of protons
• Compare hydrogen, helium and lithium
Copyright © 2010 Pearson Education, Inc. Figure 2.2
Proton
Neutron
Electron
Helium (He) Lithium (Li)Hydrogen (H)
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Identifying Elements
• Atomic number =
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Identifying Elements
• Mass number =
• Mass numbers of atoms of an element are not all identical
• Isotopes: Structural variations of elements; differ in the # of neutrons they contain
Copyright © 2010 Pearson Education, Inc. Figure 2.3
Proton
Neutron
Electron
Deuterium (2H) Tritium (3H)Hydrogen (1H)
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Molecules and Compounds
• Molecule—(H2 or C6H12O6)
• Compound—(C6H12O6)
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Chemical Bonds
• Electrons occupy up to seven electron shells (energy levels) around nucleus
• Octet rule:
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Chemically Inert Elements
• Stable and unreactive
• Outermost energy level fully occupied or contains eight electrons
Copyright © 2010 Pearson Education, Inc. Figure 2.4a
Helium (He) Neon (Ne)
2e 2e8e
(a) Chemically inert elements
Valence shell complete
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Chemically Reactive Elements
• Valence shell not fully occupied by electrons
• Tend to gain, lose, or share electrons (form bonds) with other atoms to achieve stability
Copyright © 2010 Pearson Education, Inc. Figure 2.4b
2e4e
2e8e
1e
(b) Chemically reactive elementsValence shell incomplete
Hydrogen (H) Carbon ©
1e
Oxygen (O)Sodium (Na)
2e6e
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Types of Chemical Bonds
• Ionic
• Covalent
• Hydrogen
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Ionic Bonds
• Ions are formed by transfer of valence shell electrons between atoms
• Anions (– charge)
• Cations (+ charge)
• Attraction of opposite charges results in: An ionic bond
Copyright © 2010 Pearson Education, Inc. Figure 2.5
Sodium atom (Na) Chlorine atom (Cl) Sodium ion (Na+) Chloride ion (Cl–)
Sodium chloride (NaCl)
+ –
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Covalent Bonds
• Formed by sharing of two or more valence shell electrons
• Allows each atom to fill its valence shell at least part of the time
Copyright © 2010 Pearson Education, Inc. Figure 2.7a
+
Hydrogenatoms
Carbonatom
Molecule ofmethane gas (CH4)
(a) Formation of four single covalent bonds:
or
Resulting moleculesReacting atoms
Copyright © 2010 Pearson Education, Inc. Figure 2.7b
or
Oxygenatom
Oxygenatom
Molecule ofoxygen gas (O2)
(b) Formation of a double covalent bond:
Resulting moleculesReacting atoms
+
Copyright © 2010 Pearson Education, Inc. Figure 2.7c
+ or
Nitrogenatom
Nitrogenatom
Molecule ofnitrogen gas (N2)
(c) Formation of a triple covalent bond:.
Resulting moleculesReacting atoms
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Covalent Bonds
• Sharing of electrons may be equal or unequal
• Equal sharing produces: Electrically balanced nonpolar molecules
• CO2
Copyright © 2010 Pearson Education, Inc. Figure 2.7
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Covalent Bonds
• Unequal sharing by atoms with different electron-attracting abilities produces: polar molecules
• H2O
• Atoms with six or seven valence shell electrons are electronegative, e.g., oxygen
Copyright © 2010 Pearson Education, Inc. Figure 2.7
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Hydrogen Bonds
• Attractive force between electropositive hydrogen of one molecule and an electronegative atom of another molecule
• Important in intramolecular bonds, holding a large molecule in a three-dimensional shape
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(a) The slightly positive ends (+) of the watermolecules become aligned with the slightlynegative ends (–) of other water molecules.
+
–
–
–– –
+
+
+
+
+
Hydrogen bond
Figure 2.8
Copyright © 2010 Pearson Education, Inc. Figure 2.8b
(b) High surface tension of water, due to hydrogen bonds.
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Synthesis Reactions
• A + B AB
• Always involve bond formation
• Anabolic
• Endergonic
Copyright © 2010 Pearson Education, Inc. Figure 2.9a
ExampleAmino acids are joined toForm protein.
(a) Synthesis reactions
Smaller particles are bondedtogether to form larger,
molecules.
Amino acidmolecules
Proteinmolecule
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Decomposition Reactions
• AB A + B
• Reverse synthesis reactions
• Involve breaking of bonds
• Catabolic
• Exergonic
Copyright © 2010 Pearson Education, Inc. Figure 2.9b
ExampleGlycogen is broken down to releaseglucose units.
Bonds are broken in largermolecules, resulting in smaller,
less complex molecules.
(b) Decomposition reactions
Glucosemolecules
Glycogen
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Classes of Compounds
• Inorganic compounds
• Organic compounds
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Water
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Salts
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Acids and Bases
• Both are electrolytes
• Acids :
• HCl H+ + Cl–
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Acids and Bases
• Bases-
• NaOH Na+ + OH–
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Acid-Base Concentration
• Acid solutions contain [H+]
• Basic solutions contain bases (e.g., OH–)
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pH: Acid-Base Concentration
• pH =
• Neutral solutions:
• pH = 7
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pH: Acid-Base Concentration
• Acidic solutions
• [H+], pH
• pH = 0–6.99
• Basic solutions
• [H+], pH
• pH= 7.01–14
Copyright © 2010 Pearson Education, Inc. Figure 2.13
Concentration(moles/liter)
[OH–]
100 10–14
10–1 10–13
10–2 10–12
10–3 10–11
10–4 10–10
10–5 10–9
10–6 10–8
10–7 10–7
10–8 10–6
10–9 10–5
10–10 10–4
10–11 10–3
10–12 10–2
10–13 10–1
[H+] pHExamples
1M Sodiumhydroxide (pH=14)
Oven cleaner, lye(pH=13.5)
Household ammonia(pH=10.5–11.5)
Neutral
Household bleach(pH=9.5)
Egg white (pH=8)
Blood (pH=7.4)
Milk (pH=6.3–6.6)
Black coffee (pH=5)
Wine (pH=2.5–3.5)
Lemon juice; gastricjuice (pH=2)
1M Hydrochloricacid (pH=0)10–14 100
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
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Carbohydrates
• Sugars and starches
• Three classes
• Monosaccharides
• Disaccharides
• Polysaccharides
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Carbohydrates
• Functions
• Primary role:
• Structural molecules (ribose sugar in RNA)
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Monosaccharides
• Simple sugars containing three to seven C atoms
Copyright © 2010 Pearson Education, Inc. Figure 2.15a
ExampleHexose sugars (the hexoses shown
here are isomers)
ExamplePentose sugars
Glucose Fructose Galactose Deoxyribose Ribose
(a) MonosaccharidesMonomers of carbohydrates
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Disaccharides
• Double sugars
• Too large to pass through cell membranes
Copyright © 2010 Pearson Education, Inc. Figure 2.15b
PLAYPLAY Animation: Disaccharides
ExampleSucrose, maltose, and lactose
(these disaccharides are isomers)
Glucose Fructose Glucose Glucose Glucose
Sucrose Maltose Lactose
Galactose
(b) DisaccharidesConsist of two linked monosaccharides
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Polysaccharides
• Three/more simple sugars, e.g., starch and glycogen
• Not very soluble
Copyright © 2010 Pearson Education, Inc. Figure 2.15c
PLAYPLAY Animation: Polysaccharides
ExampleThis polysaccharide is a simplified representation of
glycogen, a polysaccharide formed from glucose units.
(c) PolysaccharidesLong branching chains (polymers) of linked monosaccharides
Glycogen
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Lipids
• Insoluble in water
• Main types:
• Triglycerides
• Phospholipids
• Steroids
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Triglycerides
• Defined as:
• Composed of:
• Main functions
• Energy storage
• Insulation
• Protection
Copyright © 2010 Pearson Education, Inc. Figure 2.16a
Glycerol
+
3 fatty acid chains Triglyceride,or neutral fat
3 watermolecules
(a) Triglyceride formation
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Phospholipids
• Modified triglycerides:
• “Head” and “tail” regions have different properties
• Important in cell membrane structure
Copyright © 2010 Pearson Education, Inc. Figure 2.16b
Phosphorus-containing
group (polar“head”)
ExamplePhosphatidylcholine
Glycerolbackbone
2 fatty acid chains(nonpolar “tail”)
Polar“head”
Nonpolar“tail”
(schematicphospholipid)
(b) “Typical” structure of a phospholipid molecule
Two fatty acid chains and a phosphorus-containing group areattached to the glycerol backbone.
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Steroids
• Steroids—interlocking four-ring structure
• Examples are cholesterol, vitamin D, steroid hormones, and bile salts
Copyright © 2010 Pearson Education, Inc. Figure 2.16c
ExampleCholesterol (cholesterol is the
basis for all steroids formed in the body)
(c) Simplified structure of a steroid
Four interlocking hydrocarbon rings form a steroid.
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Proteins
• Composed of amino acids
Copyright © 2010 Pearson Education, Inc. Figure 2.17
(a) Generalized structure of all amino acids.
(b) Glycine is the simplest
amino acid.
(c) Aspartic acid (an acidic amino acid)
has an acid group (—COOH) in the
R group.
(d) Lysine (a basic amino acid) has an amine group
(–NH2) in the R group.
(e) Cysteine (a basic amino acid)
has a sulfhydryl (–SH) group in the R group, which suggests that
this amino acid is likely to participate in
intramolecular bonding.
Aminegroup
Acidgroup
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Structural Levels of Proteins
PLAYPLAY Animation: Introduction to Protein Structure
Copyright © 2010 Pearson Education, Inc. Figure 2.19a
(a) Primary structure: The sequence of amino acids forms the polypeptide chain.
Amino acid Amino acid Amino acid Amino acid Amino acid
PLAYPLAY Animation: Primary Structure
Copyright © 2010 Pearson Education, Inc. Figure 2.19b
-Helix: -Sheet:
(b) Secondary structure:The primary chain forms spirals (-helices) and sheets (-sheets).
PLAYPLAY Animation: Secondary Structure
Copyright © 2010 Pearson Education, Inc. Figure 2.19c
(c) Tertiary structure:
PLAYPLAY Animation: Tertiary Structure
Copyright © 2010 Pearson Education, Inc. Figure 2.19d
(d) Quaternary structure: Two or more polypeptide chains, each with its own tertiary structure,
combine to form a functional protein.
PLAYPLAY Animation: Quaternary Structure
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Protein Denaturation
• Shape change and disruption of active sites due to environmental changes
• A denatured protein is nonfunctional
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Enzymes
• Biological catalysts
• Increase the speed of a reaction
• Allows for millions of reactions/minute
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Substrates
Enzyme
Active site
+
Enzyme Function
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Nucleic Acids
• DNA and RNA
• Building block = nucleotide
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Deoxyribonucleic Acid (DNA)
• Four Nitrogen containing bases:
• adenine (A), guanine (G), cytosine (C), and thymine (T)
• Double-stranded, helical
• Replicates before cell division, ensuring genetic continuity
• Provides instructions for protein synthesis
Copyright © 2010 Pearson Education, Inc. Figure 2.22
Deoxyribosesugar
Phosphate
Sugar-phosphatebackbone
Adenine nucleotideHydrogen
bond
Thymine nucleotide
PhosphateSugar:
Deoxyribose PhosphateSugarThymine (T)Base:
Adenine (A)
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
(b)
(a)
(c) Computer-generated image of a DNA molecule
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Ribonucleic Acid (RNA)
• Four bases:
• adenine (A), guanine (G), cytosine (C), and uracil (U)
• Single-stranded
PLAYPLAY Animation: DNA and RNA
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Adenosine Triphosphate (ATP)
• Adenine-containing RNA nucleotide with two additional phosphate groups
Copyright © 2010 Pearson Education, Inc. Figure 2.19
Adenosine triphosphate (ATP)
Adenosine diphosphate (ADP)
Adenosine monophosphate (AMP)
Adenosine
Adenine
Ribose
Phosphate groups
High-energy phosphatebonds can be hydrolyzed
to release energy.
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Function of ATP
• Phosphorylation:
• The chemical energy contained in the high energy phosphate bonds can be used to perform cellular work
Copyright © 2010 Pearson Education, Inc. Figure 2.20
Solute
Membraneprotein
Relaxed smoothmuscle cell
Contracted smoothmuscle cell
+
+
+
Transport work
Mechanical work
Chemical work
(a)
(b)
(c)