the human body in health and illness, 4 th edition barbara herlihy chapter 2: basic chemistry 1

The Human Body in Health and Illness, 4th edition

Barbara Herlihy

Chapter 2:Basic Chemistry

1

Lesson 2-1 Objectives• Define the terms matter and element.• List the four elements that compose 96% of

body weight.• Describe the three components of an atom.• Describe the role of electrons in the formation

of chemical bonds.• Differentiate among ionic, covalent, and

hydrogen bonds.• Explain the differences among electrolytes,

ions, cations, and anions.

Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights

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Matter

• Matter: Anything that occupies space and has weight

• Matter exists in three states.– Solid– Liquid– Gas


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Matter: Two Types of Changes


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Elements

• Element: Matter composed of atoms that have the same number of positive charges in their nuclei

• Trace elements: Present in tiny amounts; essential for life


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Elements (cont’d)

• Four elements make up about 96% of human body weight.

Oxygen 65.0%Carbon 18.5%Hydrogen 9.5%Nitrogen 3.2%


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Atoms

• Atom: Smallest unit of an element with that element’s chemical characteristics

• Three subatomic particles Protons Neutrons Electrons


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Atoms (cont’d.)


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Atoms (cont’d.)


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Atoms (cont’d.)


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Atoms (cont’d.)

• Atomic number: The number of protons in the nucleus

• Atomic mass: Sum of the numbers of protons and neutrons in the nucleus of an atom

• Isotope: A different form of the same atom; same atomic number, different atomic mass


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Chemical Bonds

• Chemical bond: The electrical attraction between atoms

• Three types of chemical bonds– Covalent– Hydrogen– Ionic


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Chemical Bonds (cont’d.)

• Ionic bond: Caused by a transfer of electrons between atoms


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• Covalent bond: Involves a sharing of electrons by the outer shells of the atoms


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• Hydrogen bond: An intermolecular attraction, not caused by transfer of electrons or sharing of electrons by outer shells of the atoms


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Ions

• Ions: Atoms or groups of atoms that carry an electrical charge

• Two types of ions– Cations: Positively charged– Anions: Negatively charged

• Electrolytes: Form ions when dissolved in water


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Common Ions: Cations

Name Symbol Function

CationsSodium

Calcium

Iron

Na+

Ca2+

Fe2+

Fluid balance; nerve-muscle function

Component of bones and teeth; blood clotting; muscle contraction

Component of hemoglobin


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Common Ions: Cations (cont’d.)


Cations (cont’d.)Hydrogen

Potassium

Ammonium

H+

K+

NH4+

Important in acid-base balance

Nerve and muscle function

Important in acid-base regulation


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Common Ions: Anions


AnionsChloride

Bicarbonate

Phosphate

Cl−

HCO3−

PO43−

Primary extracellular anion

Important in acid-base regulationComponent of bones and teeth; component of ATP


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Electrolytes and Ionization

• When an electrolyte breaks apart in solution, the electrolyte is said to dissociate or ionize.


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Lesson 2-2 Objectives• Explain the difference between a molecule

and a compound.• List five reasons why water is essential to life.• Explain the role of catalysts and enzymes.


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Lesson 2-2 Objectives (cont’d.)

• Differentiate between an acid and a base.• Define pH.• Define energy and describe the role of

adenosine triphosphate (ATP) in energy transfer.

• Differentiate among mixtures, solutions, suspensions, colloidal suspensions, and precipitates.


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Molecules and Compounds• Molecule: Two

or more atoms bonded together

• Compound: Molecules formed bytwo or more different atoms


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Water: A Vital Substance

• Universal solvent• Temperature regulator• Ideal lubricant• Crucial part of most chemical reactions• Protective mechanism


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Chemical Reactions

• Chemical reaction: The interaction of atoms of molecules or compounds to form new chemical combinations

• Catalysts: Chemical substances that speed up the rate of a chemical reaction

• Enzymes: Proteins that serve as catalysts


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Acids and Bases

• Acid: An electrolyte that dissociates into H+ (hydrogen ion) and an anion

• Base: Substance, often OH- (hydroxyl ion), that combines with H+ to make a solution less acidic

• Acids and bases can be strong or weak


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pH Scale

• pH: Unit of measurement indicating how many hydrogen ions are in a solution

• pH scale: Ranges from 0 to 14

• Midpoint of scale: pH 7, or neutral


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Normal blood pH: 7.35 to 7.45

• Acidosis– Too many H+ ions– pH less than 7.35

• Alkalosis– Too few H+ ions– pH greater than 7.45


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Energy: Ability to Perform Work• Six forms of energy– Mechanical – Chemical – Electrical – Radiant – Thermal – Nuclear


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Energy Transfer

• Adenosine triphosphate (ATP): Energy transfer molecule

• Three parts of ATP– Base– Sugar– Three phosphate groups


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Energy Transfer (cont’d.)


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• After the food we eat is broken down, energy is released. This energy is transferred to ATP so it can be used by the cells of the body.


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Mixtures

• Mixtures: Combinations of two or more substances that can be separated by ordinary physical means.

• Example: A sugar-iron mixture can be separated by a magnet.


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Solutions

• Solutions have two parts that remain evenly distributed (e.g., normal saline).– Solute: Substance present in smaller amount; is

the substance being dissolved– Solvent: Part of solution present in greater

amount; does the dissolving

• Two types of solutions– Aqueous solutions– Tinctures


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Suspensions and Precipitates

• Suspensions: Mixtures with relatively large particles

• Colloidal suspension: Particles remain suspended within the liquid.

• Precipitates: Solids are formed and fall out of solution during a chemical reaction.


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the human body in health and illness, 4 th edition barbara herlihy chapter 2: basic chemistry 1

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life copyright

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ions ions

atoms atom

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