Transcript CH 2 Lecture

Chapter 2
Lecture Notes
Matter and Energy
 Matter – anything that occupies space and has mass
(weight); the “stuff” of the universe
 3 states of matter:
 Solid
 Liquid
 Gas
Matter and Energy
 Energy – the ability to do work; putting matter into
motion; massless
 4 forms of energy:
 Chemical
 Electrical
 Mechanical
 Radiant
Composition of Matter
 Elements – fundamental units of matter
 Periodic table – lists all 112 elements, their 1 or 2
letter symbols, atomic number, and atomic weights
 4 elements compose approximately 96% of the
human body:
 Carbon (C)
 Oxygen (O)
 Hydrogen (H)
 Nitrogen (N)
Atomic Structure
 Atoms – building blocks of elements
 Nucleus – center of every atom an contains:
 Protons (p+) = positive charge
 Neutrons (n0) = no charge
 Outside of the nucleus contains:
 Electrons (e-) = negative charge
Atomic Structure
Identifying Elements
 Atomic Number – equal to the number of protons that
the atom contains
 Atomic Mass – the sum of the protons and the
neutrons
Molecules and Compounds
 Molecule – 2 or more LIKE atoms combined
chemically
 Example: H (atom) + H (atom) = H2
 Compound – 2 or more DIFFERENT atoms combined
chemically
 Example: 4H + C = CH4 (methane)
Chemical Bonds and Reactions
 Chemical Reactions – occur whenever atoms combine
with, or dissociate from, other atoms
 Atoms are united by chemical bonds
 Electrons occupy energy levels called electron shells
 Electrons closest to the nucleus are most strongly
attracted
Chemical Bonds and Reactions
 Each electron shell has distinct properties:
 Number of electrons has an upper limit
 Shells closest to nucleus fill first
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Shell 1 can hold 2 electrons
Shell 2 can hold 8 electrons
Shell 3 can hold 18 electrons
Chemical Bonds and Reactions
 Valence Shell – outermost shell that contains
electrons
 Bonding involves interactions between electrons in
the valence shell
 Full valence shells do not form bonds
 Inert Elements – have complete valence shells and
are stable
 Rule of 8’s – atoms interact so that they will have 8
electrons in their valence shell
Types of Chemical Bonds
 Ionic Bonds – form when electrons are completely
transferred from one atom to another
 Na + Cl = NaCl
 Ions – are charged particles; they either donate or
accept electrons
 Anions = negative ions
 Cations = positive ions
Types of Chemical Bonds
 Covalent Bonds – shared electron bonding
 Single covalent bonds share one electron
H + H = H2
 Double covalent bonds share two electrons
O + O = O2
 Hydrogen Bonds – weak covalent bond where H is
attracted to negative portion of a polar molecule
Examples of Covalent Bonds
Types of Chemical Reactions
 Synthesis Reaction – atoms or molecules combine and
energy is absorbed for bond formation
 A + B = AB
 Decomposition – molecule is broken down and energy
is released
 AB = A + B
Examples of Chemical Reactions
Types of Chemical Reactions
 Exchange Reactions – involves both synthesis and
decomposition reactions. A switch is made between
molecule parts and different molecules are made.
 AB + CD = AD + CB
Biochemistry: Essentials for Life
 Two major classes of molecules:
 Organic Compounds = contain carbon and most are
covalently bonded
 Inorganic Compounds = lack carbon and tend to be
simpler compounds
Organic Compounds
 Carbohydrates – contain C, H, and O and include
sugars and starches; are classified according to
their size:
 Monosaccharides – simple sugars
 Glucose
 Disaccharides – 2 simple sugars joined by
dehydration synthesis or hydrolysis
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Sucrose = glucose + fructose
 Polysaccharides – long branching chains of linked
simple sugars
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Starch
glycogen
Examples of Sugars
Examples of Sugars
Organic Compounds
 Lipids – contain C, H, and O; C and H outnumber O;
are insoluble in water
 Triglycerides (neutral fats) – found in fat deposits and
are composed of fatty acids and glycerol; source of
stored energy
 Phospholipids – form cell membrane
 Steroids – include cholesterol, vitamin D, and some
hormones
Organic Compounds
 Proteins – contain C, O, H, N and sometimes S; made
up of amino acids
 Account for over half of the body’s organic matter
 Provides for construction materials for body tissues
 Plays a vital role in cell function
 Act as enzymes, hormones, and antibodies
 Enzymes = act as biological catalysts which increase the rate
of chemical reactions
Organic Compounds
 Nucleic Acids – provide the blueprint for life; make
DNA and RNA and are composed of nucleotide
bases:
 Adenine
 Guanine
 Cytosine
 Thymine – found only in DNA
 Uracil – found only in RNA
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DNA = DeOxyRiboNucleic Acid – provides instruction for
every protein in the body
RNA = RiboNucleic Acid
DNA
Organic Compounds
 Adenosine TriPhosphate (ATP) – chemical energy
used by all cells; energy is released by breaking high
energy phosphate bonds and producing ADP
Inorganic Compounds
 H2O (water) – most abundant inorganic compound
 Salts – easily dissociate into ions in the presence of
water and they are vital to many body functions;
include the electrolytes which conduct electrical
currents
Inorganic Compounds
 Acids – are proton donators; can release detectable H
ions; have a sour taste and can dissolve many metals or
“burn” holes in materials
 Bases – are proton acceptors; have a bitter taste and
feel slippery
 Neutralization Reaction = acids and bases react to
form water and a salt
pH Measurements
 pH = measures relative concentrations of H ions
 pH 7 = neutral
 pH < 7 = acidic
 pH > 7 = basic
 Buffers = chemicals that can help regulate pH change