Chapter 2 introductory chemistry

Chapter 2:
Introductory Chemistry
© 2013 John Wiley & Sons, Inc. All rights reserved.

Introduction to Chemistry – Chemical
Elements and Atoms
 All forms of matter are made up of a limited
number of building blocks called chemical
elements, substances that cannot be broken
down into a simpler form by ordinary
chemical means
 Each element is designated by a chemical
symbol

Chemical Elements and Atoms

Chemical Elements and Atoms
 Each element is made up of atoms, the
smallest units of matter that retain the
properties and characteristics of the element
 An atom consists of two basic parts
 A nucleus (protons and neutrons)
 One or more electrons

Chemical
Elements
and Atoms

Atomic Structures of Several Atoms

Ions, Molecules, and Compounds
 A ____ consists of two or more atoms
sharing electrons
 A ___ ___ indicates the number and type of
atoms that make up a molecule
 A ____ is a substance containing atoms of
two or more different elements
 A ___ ___ is an ion or molecule that has an
unpaired electron in its outermost shell

Ions, Molecules, and Compounds
 A molecule consists of two or more atoms
sharing electrons
 A molecular formula indicates the number
and type of atoms that make up a molecule
 A compound is a substance containing
atoms of two or more different elements
 A free radical is an ion or molecule that has
an unpaired electron in its outermost shell

Animation:
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• Chemical Bonding

Molecules

Chemical Bonds –
Ions and
Ionic Bonds

Animation:
• Polarity and Solubility of Molecules

Chemical Bonds – Covalent Bonds
 The polar covalent
bonds that form
between hydrogen
atoms and other
atoms can give rise
to a third type of
chemical bond, a
hydrogen bond

Chemical Reactions – Synthesis

Chemical Reactions – Decomposition

Chemical Reactions – Exchange

Chemical Reactions – Reversible

Animation:
• Types of Reactions and Equilibrium

Introduction to Chemistry
 Matter is made up of chemical elements. The elements oxygen (O), carbon
(C), hydrogen (H), and nitrogen (N) make up 96% of the body’s mass.
 Each element is made up of units called atoms, which consist of a nucleus
that contains protons and neutrons, and electrons that move about the
nucleus in electron shells.
 The atomic number, the number of protons, distinguishes the atoms of one
element from those of another element.
 The combined total of protons and neutrons in an atom is its mass number.
 An atom that gives up or gains electrons becomes an ion—an atom that has
a positive or negative charge.

 A molecule is a substance that consists of two or more
chemically combined atoms.
 A compound is a substance that can be broken down into two
or more different elements by ordinary chemical means.
 A free radical is a destructive ion or molecule that has an
unpaired electron in its outermost shell.
 Chemical bonds hold the atoms of a molecule together.
Electrons in the valence shell (outermost shell) are the parts of
an atom that participate in chemical reactions (are involved in
forming and breaking bonds).

 Ionic bonds are formed when outer shell electrons are transferred from one
atom to another, the transfer forms ions with unlike charges that attract the
ions to each other. In a covalent bond, pairs of outer shell electrons are
shared between two atoms.
 Hydrogen bonds are weak bonds between hydrogen and certain other
atoms.
 Energy is the capacity to do work.
 Potential energy is energy stored by matter due to its position.
 Kinetic energy is the energy of matter in motion.

 In a synthesis reaction (anabolic reaction), two or more atoms, ions, or
molecules combine to form a new and larger molecule. In a decomposition
reaction (catabolic reaction), a molecule is split apart into smaller
molecules, ions, or atoms.
 When nutrients such as glucose are broken down via decomposition
reactions, some of the energy released is temporarily stored in adenosine
triphosphate (ATP) and then later used to drive energy requiring synthesis
reactions that build body structures, such as muscles and bones.
 Exchange reactions are combination synthesis and decomposition
reactions. Reversible reactions can proceed in both directions under
different conditions.

Chemical Compounds and Life
Processes
 Organic compounds – all are carbon-based
 Example: C6H12O6 (glucose)
 Inorganic compounds – Most lack carbon
 Tend to be simpler compounds
 Examples: H2O (water), NaCl (table salt),
CO2 (carbon dioxide)
 Question – Where does all the carbon in
organic compounds originate?

Inorganic Compounds – Water
 Critical properties of water to sustain
organisms
 Water is an excellent ____
 Water participates in ____ reactions
 Water absorbs and releases ____ very slowly
 Water requires a large amount of ____ to
change from a liquid to a gas
 Water serves as a ____

Inorganic Compounds – Water
 Critical properties of water to sustain
organisms
 Water is an excellent solvent
 Water participates in chemical reactions
 Water absorbs and releases heat very slowly
 Water requires a large amount of heat to change
from a liquid to a gas
 Water serves as a lubricant

Inorganic Compounds – Acids, Bases,
and Salts
 ____ - release highly reactive hydrogen ions
(H+
) into solution
 ____ - release highly reactive hydroxyl ions
(OH–
) into solution
 ____ reaction - acids and bases react to
form water and a salt
 ____ - easily dissociate into ions in the
presence of water, vital to many life
processes (e.g. electrolytes conduct
electrical currents)

and Salts
 Acids - release highly reactive hydrogen ions
(H+
) into solution
 Bases - release highly reactive hydroxyl ions
(OH–
) into solution
 Neutralization reaction - acids and bases
react to form water and a salt
 Salts - easily dissociate into ions in the
presence of water, vital to many life
processes (e.g. electrolytes conduct
electrical currents)

and Salts

Inorganic Compounds – pH
 Neutral
pH = 7

Animation:
• Acids and Bases

Inorganic Compounds – pH

Inorganic Compounds – Buffers
 Chemical compounds that act quickly to
temporarily bind H, removing the highly
reactive, excess H from solution but not from
the body
 Prevent rapid, drastic changes in the pH of a
body fluid
Less Reactive

Organic Compounds – Carbohydrates
 Sugars and starches
 Categorized by size
 Monosaccharides—simple sugars
 Disaccharides—two simple sugars linked
together
 Polysaccharides—long-branching chains of
linked monosaccharides

Carbohydrates – Monosaccharides and
Disaccharides

Carbohydrates – Polysaccharides

Anatomy Overview:
• Common Biomolecules

Organic Compounds – Lipids
 There are 3 principle lipids in the human
body
 ____ (triglycerides) – stored fat deposits
 ____ – form cellular membranes
 ____ – lipid-based hormones, cholesterol, bile
salts, & vitamin D

Organic Compounds – Lipids
 There are 3 principle lipids in the human
body
 Neutral fats (triglycerides) – stored fat deposits
 Phospholipids – form cellular membranes
 Steroids – lipid-based hormones, cholesterol,
bile salts, & vitamin D

Triglycerides

Phospholipids

Steroids

Organic Compounds – Proteins
 Consist of chains of ____ acids
 Make up over half of a body’s organic matter
 Function as enzymes, hormones, and
antibodies
 If a protein encounters a hostile environment
in which temperature, pH, or ion
concentration is significantly altered, it may
unravel and lose its characteristic shape
 This process is called ____
 ____ proteins are no longer functional

 Consist of chains of amino acids
 Make up over half of a body’s organic matter
 Function as enzymes, hormones, and
antibodies
 If a protein encounters a hostile environment
in which temperature, pH, or ion
concentration is significantly altered, it may
unravel and lose its characteristic shape
 This process is called denaturation
 Denatured proteins are no longer functional

Actions of an Enzyme
The substrates attach to the active site of
the enzyme molecule, the specific part of the
enzyme that catalyzes the reaction, forming
a temporary compound called the enzyme–
substrate complex. In this reaction, the
substrates are the disaccharide sucrose and
a molecule of water.
The substrate molecules are transformed
by the rearrangement of existing atoms, the
breakdown of the substrate molecule, or the
combination of several substrate molecules
into products of the reaction. Here the
products are two monosaccharides: glucose
and fructose.
After the reaction is completed and the
reaction products move away from the
enzyme, the unchanged enzyme is free to
attach to another substrate molecule.

Organic Compounds – Nucleic Acids
 ____ – provides the blueprint of life
 Nucleotide bases: A=Adenine G=Guanine C=Cytosine
T=Thymine
 ____ – intermediary between DNA and
protein
U=Uracil
 ____ ____ (____)
 Chemical energy used by all cells
 Energy released when high energy phosphate
bond is broken

 DNA – provides the blueprint of life
T=Thymine
 RNA – intermediary between DNA and
protein
U=Uracil
 Adenosine triphosphate (ATP)
 Chemical energy used by all cells
 Energy released when high energy phosphate
bond is broken

DNA

Structure of ATP and ADP

Animation:
• Enzyme Functions and ATP

Processes
 Inorganic compounds usually are structurally simple and lack carbon.
Organic compounds always contain carbon, usually contain hydrogen, and
always have covalent bonds.
 Water is the most abundant substance in the body. It is an excellent
solvent, participates in chemical reactions, absorbs and releases heat
slowly, requires a large amount of heat to change from a liquid to a gas, and
serves as a lubricant.
 Inorganic acids, bases, and salts dissociate into ions in water. An acid
ionizes into hydrogen ions (H); a base usually ionizes into hydroxide ions
(OH2). A salt ionizes into neither H nor OH ions.

Processes
 The pH of body fluids must remain fairly constant for the body to maintain
homeostasis. On the pH scale, 7 represents neutrality. Values below 7
indicate acidic solutions, and values above 7 indicate basic (alkaline)
solutions.
 Buffer systems help maintain pH by converting strong acids or bases into
weak acids or bases.
 Carbohydrates include sugars, glycogen, and starches. They may be
monosaccharides, disaccharides, or polysaccharides. Carbohydrates
provide most of the chemical energy needed to generate ATP.

Processes
 Carbohydrates, and other large, organic molecules, are synthesized via
dehydration synthesis reactions, in which a molecule of water is lost. In
the reverse process, called hydrolysis, large molecules are broken down
into smaller ones upon the addition of water.
 Lipids are a diverse group of compounds that include triglycerides (fats
and oils), phospholipids, and steroids. Triglycerides protect, insulate,
provide energy, and are stored in adipose tissue. Phospholipids are
important membrane components. Steroids are synthesized from
cholesterol.
 Proteins are constructed from amino acids. They give structure to the
body, regulate processes, provide protection, help muscles to contract,
transport substances, and serve as enzymes.

Processes
 Enzymes are molecules, usually proteins, that speed up chemical reactions
and are subject to a variety of cellular controls.
 DNA is a double helix and is the primary chemical in genes. RNA differs in
structure and chemical composition from DNA; its main function is to carry
out the instructions encoded in DNA for protein synthesis.
 Adenosine triphosphate (ATP) is the principal energy-transferring
molecule in living systems. When it transfers energy, ATP is decomposed
by hydrolysis to adenosine diphosphate (ADP) and P . ATP is synthesized
from ADP and P using primarily the energy supplied by the breakdown of
glucose.

End of Chapter 2
Copyright 2013 John Wiley & Sons, Inc. All rights
reserved. Reproduction or translation of this work
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Chapter 2 introductory chemistry

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