Hit1614-HBHD-Ch2

Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins
Chapter 2
Chemistry, Matter, and Life

Copyright © 2015 Wolters Kluwer • All Rights Reserved
Overview

Key Terms
acid chemistry ion salt
amino acid colloid isotope solute
anion compound lipid solution
aqueous denaturation molecule solvent
atom electrolyte nucleotide steroid
base electron neutron substrate
buffer element pH suspension
carbohydrate enzyme protein valence
catalyst glucose proton
cation glycogen radioactive

Chemistry
• Science that deals with matter’s composition and
properties
• Used to understand normal and abnormal body function

Elements
Learning Objectives
1.Define a chemical element.
2.Describe the structure of an atom.

Chemical Bonds
Learning Objectives
3.Differentiate between ionic and
covalent bonds.
4.Define an electrolyte.
5.Differentiate between molecules
and compounds.

Mixtures
Learning Objectives
6.Define mixture; list the three types
of mixtures, and give two examples
of each.
7.Explain why water is so important
in metabolism.

Acids, Bases, and Salts
Learning Objectives
8.Compare acids, bases, and salts.
9.Explain how the numbers on the pH
scale relate to acidity and alkalinity.
10.Explain why buffers are important
in the body.

Isotopes and Radioactivity
Learning Objective
11.Define radioactivity, and cite
several examples of how radioactive
substances are used in medicine.

Organic Compounds
Learning Objectives
12.Name the three main types of
organic compounds and the building
blocks of each.
13.Define enzyme; Describe how
enzymes work.
14.List the components of nucleotides
and give some examples of
nucleotides.

Case Study
Learning Objective
15. Use the case study to discuss the
importance of regulating body
fluid quantity and composition.

Word Anatomy
Learning Objective
16. Show how word parts are used to build words related
to chemistry, matter, and life.

Elements (cont.)
Matter
• The substances from which the universe is made
Elements
• All of the different types of matter
• Identified by names or chemical
symbols
• Also identified by number
• Described and organized in the
periodic table
11
Sodium
Na
22.99

Appendix 1 Periodic Table of the Elements
What is the symbol and number for carbon?
Elements (cont.)

Table 2-1 Some Common Elements
Name Symbol Function
Oxygen O Part of water; needed to
metabolize nutrients for energy
Carbon C Basis of all organic compounds;
component of carbon dioxide,
the gaseous byproduct of
metabolism
Hydrogen H Part of water, participates in
energy metabolism; determines
the acidity of body fluids
Nitrogen N Present in all proteins, ATP (the
energy-storing compound), and
nucleic acids (DNA and RNA)
Calcium Ca Builds bones and teeth; needed
for muscle contraction, nerve
impulse conduction, and blood
clotting
Phosphorus P Active ingredient in ATP; builds
bones and teeth; component of
cell membranes and nucleic
acids
Potassium K Active in nerve impulse
conduction; muscle contraction
Sulfur S Part of many proteins
Sodium Na Active in water balance, nerve
impulse conduction, and muscle
contraction
Iron Fe Part of hemoglobin, the
compound that carries oxygen
in red blood cells
The elements are listed in decreasing order by weight in the body.
Elements (cont.)

Elements (cont.)
• Living matter contains 26 of 92 natural elements.
• 96% of body weight—four elements
• 4% of body weight—nine elements
• 0.1% of body weight—13 elements

Figure 2-1 The body’s chemical composition by weight.
Elements (cont.)

Elements (cont.)
Atoms
• Smallest subunits of elements
• Cannot be broken down or changed by ordinary chemical
and physical means

Elements (cont.)
Atomic Structure
• Nucleus
– At atom’s center
– Composed of
• Protons; positively charged
• Neutrons; not charged
• Electrons
– Negatively charged
– Orbit in energy levels around the nucleus
– Determine atom’s chemical reactivity

Figure 2-2 The oxygen atom.
How does the proton number of this atom compare with
the electron number?
Elements (cont.)

Elements (cont.)
Atomic Number
• Equal to the number of protons in
an atom’s nucleus.
• Also represents the number of
electrons orbiting the nucleus.
• No two elements share the same
atomic number.
8
Oxygen
O
16.00
Oxygen’s nucleus
contains eight
protons. Its
atomic number is
8.

Elements (cont.)
Energy Levels
• Regions around an atom’s nucleus where electrons orbit.
• Each region has space for a specific number of electrons.
– The first energy level has room for two electrons.
– The second energy level has room for eight electrons.
• An atom is most stable when its energy levels are
filled with electrons.

Elements (cont.)
Energy Levels (cont.)
• Hydrogen has only one energy level with room for one
more electron.
• Carbon’s first energy level is full.
• Carbon’s second energy level has room for four more
electrons.
Hydrogen Carbon
Total number of electrons 1 6
Number of electrons in first energy level 1 2
Number of electrons in second energy level 0 4

Elements (cont.)
Energy Levels (cont.)
• An atom will form chemical bonds with other atoms to
fill its outermost energy level.
An atom will donate, accept, or share electrons to fill its
outermost energy level.

Figure 2-3 Examples of atoms.
How many electrons does oxygen need to complete its
outermost energy level? How does magnesium achieve a
stable outermost energy level?
Elements (cont.)

Elements (cont.)
✓
Checkpoints
2-1 What are atoms?
2-2 What are three types of particles found in atoms?
2-3 Which of these atoms would be more likely to
participate in a chemical reaction—an atom with eight
electrons in its outermost energy level or an atom with
six electrons in its outermost energy level?

Elements (cont.)
?
Pop Quiz
2.1 Which element makes up the greatest
percentage of body weight?
A)Nitrogen
B)Oxygen
C)Potassium
D)Sodium

Elements (cont.)
?
Pop Quiz Answer
2.1 Which element makes up the greatest
percentage of body weight?
A)Nitrogen
B)Oxygen
C)Potassium
D)Sodium

Elements (cont.)
?
Pop Quiz
2.2 The atomic number of iron is 26. How many
protons does iron have?
A)13
B)26
C)39
D)52

Elements (cont.)
?
Pop Quiz Answer
2.2 The atomic number of iron is 26. How many
protons does iron have?
A)13
B)26
C)39
D)52

Chemical Bonds (cont.)
• An atom forms chemical bonds with other atoms to fill
its outermost energy level with electrons.
– Electrons may be transferred between atoms.
– Electrons may be shared between atoms.

Valence
The number of bonds an atom needs to fill its outermost
energy level.
Example
• A carbon atom has six electrons.
• Its outermost energy level contains four
electrons.
• It needs four more electrons to fill its
outermost energy level.
• Carbon’s valence is 4.
6
Carbon
C
12.01

Ionic Bonds
• Form when one atom transfers electrons
to another atom
– The atom that donates an electron
becomes a positively charged cation.
– The atom that accepts an electron
becomes a negatively charged anion.
– The ionic bond is the attraction
between oppositely charged ions.
Na+
Cl–
Na+
Cl–

Figure 2-4 Ionic bonding.
How many electrons are in the
outermost energy level of a
sodium atom? Of a chlorine atom?

Electrolytes
• Compounds that separate into ions in solution
• Term also used to refer to the ions themselves
Example
Sodium chloride (NaCl) is an electrolyte.
When NaCl is added to water, it separates into Na+
and Cl−
ions.
Both Na+
and Cl−
ions are electrolytes.

Ions in the Body
• Ions play important physiologic roles in body fluid.
• Homeostasis maintains proper ion concentration.
Examples
Ion Functions
Ca2+
Blood clotting, muscle contraction
HCO3
−
pH regulation

Ions in the Body (cont.)
• Ions conduct electric currents in body fluid.
• Measurement of a tissue’s electrical activity is used to
diagnose disease.
Examples
Electrocardiogram A record of the heart’s electrical activity
Electroencephalogram A record of the brain’s electrical activity

Covalent Bonds
• Form when two atoms share electrons
• The most common chemical bond in the body
• Types:
– Nonpolar covalent bond
• Electrons are shared equally.
– Polar covalent bond
• Electrons are shared unequally.

Figure 2-5 A nonpolar covalent bond.
How many electrons are needed to complete the energy
level of each hydrogen atom?

Figure 2-6 Formation of water.
How many hydrogen atoms bond with an oxygen atom
to form water?

Molecules
• Chemicals composed of two or more atoms held
together with covalent bonds
– Examples: O2, H2O
Compounds
• Chemicals composed of two or more different atoms
held together by ionic or covalent bonds
– Examples: NaCl, H2O, CO2

✓
Checkpoints
2-4 Which type of chemical bond is formed by an
exchange of electrons? Which type is formed by a
sharing of electrons?
2-5 What happens when an electrolyte goes into
solution?
2-6 What are molecules and what are compounds?

?
Pop Quiz
2.3 What bond forms between two atoms that
share their electrons equally?
A)Hydrogen bond
B)Ionic bond
C)Nonpolar bond
D)Polar bond

?
Pop Quiz Answer
2.3 What bond forms between two atoms that
share their electrons equally?
A)Hydrogen bond
B)Ionic bond
C)Nonpolar bond
D)Polar bond

?
Pop Quiz
2.4 Which term best describes the sodium ion
(Na+
)?
A)Anion
B)Atom
C)Electrolyte
D)Element

?
Pop Quiz Answer
2.4 Which term best describes the sodium ion
(Na+
)?
A)Anion
B)Atom
C)Electrolyte
D)Element

?
Pop Quiz
2.5 Which chemical is NOT a compound?
A)CO2
B)H2O
C)NaCl
D)O2

?
Pop Quiz Answer
2.5 Which chemical is NOT a compound?
A)CO2
B)H2O
C)NaCl
D)O2

Mixtures (cont.)
Table 2-2 Mixtures
Type Definition Example
Solution Homogeneous mixture formed
when one substance (solute)
dissolves in another (solvent)
Table salt (NaCl)
dissolved in water;
table sugar
(sucrose) dissolved
in water
Suspension Heterogeneous mixture in which
one substance is dispersed in
another but will settle out unless
constantly mixed
Red blood cells in
blood plasma; milk
of magnesia
Colloid Heterogeneous mixture in which
the suspended particles remain
evenly distributed based on the
small size and opposing charges
of the particles
Blood plasma;
cytosol

Mixtures (cont.)
The Importance of Water
• Most abundant compound in body
• Critical in all physiologic processes
• Deficiency (dehydration) threatens health
• Universal solvent
• Stable liquid at ordinary temperatures
• Participates in body’s chemical reactions

Mixtures (cont.)
✓
Checkpoints
2-7 What is the difference between solutions and
suspensions?
2-8 What is the most abundant compound in the body?

Mixtures (cont.)
?
Pop Quiz
2.6 Which term describes a substance that
dissolves another substance?
A)Mixture
B)Solute
C)Solution
D)Solvent

Mixtures (cont.)
?
Pop Quiz Answer
2.6 Which term describes a substance that
dissolves another substance?
A)Mixture
B)Solute
C)Solution
D)Solvent

Mixtures (cont.)
?
Pop Quiz
2.7 Which substance is termed the universal
solvent?
A)An acid
B)A base
C)Carbon
D)Water

Mixtures (cont.)
?
Pop Quiz Answer
2.7 Which substance is termed the universal
solvent?
A)An acid
B)A base
C)Carbon
D)Water

Acids, Bases, and Salts (cont.)
Acid
• A substance that releases hydrogen ions
Base
• A substance that releases hydroxide ions and accepts
hydrogen ions
Salt
• A substance formed by a reaction between an acid and a
base
HCl  H+
+ Cl−
NaOH  Na+
+ OH−
HCl + NaOH  NaCl + H2O

The pH Scale
• Measures the relative concentrations of hydrogen and
hydroxide ions in a solution.
– Scale from 0 (most acidic) to 14 (most basic).
– Each unit represents a 10-fold change.
• Normal body fluid pH range is between 7.35 and 7.45.
– Acidosis: Body fluid pH less than 7.35
– Alkalosis: Body fluid pH greater than 7.45

Figure 2-7 The pH scale.
What happens to the amount of hydroxide ion (OH–
)
present in a solution when the amount of hydrogen ion
(H+
) increases?

Buffers
• Chemicals that prevent sharp changes in H+
concentration
• Are important in maintaining a relatively constant pH in
body fluids

✓
Checkpoints
2-9 What number is neutral on the pH scale? What kind
of compound measures lower than this number?
Higher?
2-10 What is a buffer?

?
Pop Quiz
2.8 Which substance always accepts hydrogen
ions?
A)An acid
B)A base
C)A buffer
D)A salt

?
Pop Quiz Answer
2.8 Which substance always accepts hydrogen
ions?
A)An acid
B)A base
C)A buffer
D)A salt

?
Pop Quiz
2.9 Which substance always has a pH below 7?
A)An acid
B)A base
C)A buffer
D)A salt

?
Pop Quiz Answer
2.9 Which substance always has a pH below 7?
A)An acid
B)A base
C)A buffer
D)A salt

?
Pop Quiz
2.10 Which substance is most important in
maintaining a relatively constant pH in body fluids?
A)An acid
B)A base
C)A buffer
D)A salt

?
Pop Quiz Answer
2.10 Which substance is most important in
maintaining a relatively constant pH in body fluids?
A)An acid
B)A base
C)A buffer
D)A salt

Isotopes and Radioactivity (cont.)
Isotopes
• Forms of an element that have the same atomic number
but different atomic weight
– Different atomic weight because of a different
number of neutrons
• May be stable or unstable (radioactive)
Examples
Isotope
Proton
Number
Neutron
Number
Atomic Weight
Carbon-12 6 6 12
Carbon-13 6 7 13
Carbon-14 6 8 14

Radioactivity
• Emission of atomic particles from an isotope
Use of Radioactive Isotopes
• Used in the treatment of cancer
– Radiation penetrates and destroys tumor cells.
• Used in diagnosis
– Radioactive elements can be administered and
detected internally to identify abnormalities—these
are called tracers. Example: Radioactive iodine used
to diagnose thyroid problems.

✓
Checkpoint
2-11 What word is used to describe isotopes that give off
radiation?

?
Pop Quiz
2.11 A form of an element that differs in its atomic
weight from other forms of that same element is a(n)
____________.
A)Compound
B)Ion
C)Isotope
D)Molecule

?
Pop Quiz Answer
2.11 A form of an element that differs in its atomic
weight from other forms of that same element is a(n)
____________.
A)Compound
B)Ion
C)Isotope
D)Molecule

Organic Compounds
Learning Objectives
12.Name the three main types of
organic compounds and the building
blocks of each.
13.Define enzyme; describe how
enzymes work.
14.List the components of
nucleotides, and give some examples
of nucleotides.

Organic Compounds (cont.)
Chemistry of Living Matter
• Hydrogen, oxygen, carbon, and nitrogen make up 96%
of body weight.
Organic Compounds
• Chemical compounds found in living things
• Built on the element carbon
• Main types
– Carbohydrates
– Lipids
– Proteins

Carbohydrates
• Monosaccharides
– Basic units of carbohydrates
• Disaccharides
– Two monosaccharides linked together
• Polysaccharides
– Many monosaccharides linked together
Carbohydrate Examples
Monosaccharide Glucose
Disaccharide Sucrose and lactose
Polysaccharide Glycogen and starch

Figure 2-8 Examples of carbohydrates.
What are the building blocks (monomers) of disaccharides
and polysaccharides?

Lipids (Fats)
• Triglycerides
– Simple fat composed of glycerol and three fatty acids
• Phospholipids
– Complex lipid containing phosphorus
• Steroids
– Contain rings of carbon atoms (e.g., cholesterol)
Lipid Functions
Triglyceride Insulates body, protects organs, stores energy
Phospholipid Main component of cell membranes
Steroid Regulate body function (e.g., cortisol, sex hormones)

Figure 2-9 Lipids.
How many carbon atoms
are in glycerol?

Proteins
• Contain nitrogen (and sometimes sulfur or phosphorus).
• Found as structural materials and metabolically active
compounds.
• Composed of chains of amino acids held together by
peptide bonds.
• The overall three-dimensional shape of a protein is
caused by folding.

Figure 2-10 Proteins.
What part of an amino acid contains nitrogen?

Enzymes
• Are proteins that speed up (catalyze) chemical reactions
• Work on specific substrates
• Are not used up or changed during a chemical reaction
• Work via the “lock-and-key” mechanism
• Denature in harsh conditions (e.g., extremes of
temperature or pH)

Figure 2-11 Diagram of enzyme action.
How does the shape of the enzyme before the reaction
compare with its shape after the reaction?

Nucleotides
• Composed of:
– A nitrogenous base
– A sugar (usually ribose or deoxyribose)
– A phosphate group
• Building blocks of DNA and RNA
• One type is a component of ATP

Figure 2-12 Nucleotides.
What does the prefix tri- in adenosine triphosphate mean?

✓
Checkpoints
2-12 What element is the basis of organic chemistry?
2-13 What are the three main categories of organic
compounds?
2-14 What is an enzyme?
2-15 What is in a nucleotide, and what compounds are
made of nucleotides?

?
Pop Quiz
2.12 Which element is the basis of organic
chemistry?
A)Carbon
B)Hydrogen
C)Nitrogen
D)Oxygen

?
Pop Quiz Answer
2.12 Which element is the basis of organic
chemistry?
A)Carbon
B)Hydrogen
C)Nitrogen
D)Oxygen

?
Pop Quiz
2.13 Which organic compound catalyzes metabolic
reactions?
A)Carbohydrate
B)Enzyme
C)Lipid
D)Nucleotide

?
Pop Quiz Answer
2.13 Which organic compound catalyzes metabolic
reactions?
A)Carbohydrate
B)Enzyme
C)Lipid
D)Nucleotide

?
Pop Quiz
2.14 Which organic compound is used to store
genetic information?
A)Carbohydrate
B)Enzyme
C)Lipid
D)Nucleotide

?
Pop Quiz Answer
2.14 Which organic compound is used to store
genetic information?
A)Carbohydrate
B)Enzyme
C)Lipid
D)Nucleotide

?
Pop Quiz
2.15 A substance that has a name ending in -ase
is most likely a(n)?
A)Carbohydrate
B)Enzyme
C)Lipid
D)Nucleotide

?
Pop Quiz Answer
2.15 A substance that has a name ending in -ase
is most likely a(n)?
A)Carbohydrate
B)Enzyme
C)Lipid
D)Nucleotide

Case Study (cont.)
Margaret’s Case: Chemistry’s Role in Health Science
• Some terms that illustrate the importance of body fluid
quantity and composition:
– Dehydration
– Hematocrit
– Hypernatremia
– Hypotension
– Tachycardia

Word Anatomy (cont.)

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