ANATOMY & PHYSIOLOGY
Chapter 2: Introductory Chemistry
Objectives
1. Define ion, molecule, and compound.
2. Explain how chemical bonds form.
3. Describe what happens in a chemical reaction
and explain why it is important to the human
body.
Intro to Chemistry
Ions, Molecules, and Compounds
ions
if an atom either gives up or gains electrons,
it becomes an ion
a. symbolized by writing its chemical
symbol followed by pos.(+) or neg.(-)
b. list ions in the body and their important
functions
Ions, Molecules, and Compounds
Molecule
when two or more atoms share electrons
a. may consist of two or more atoms of the
same element or two or more atoms of
different elements
b. (give an example of each above)
O2
H2O
Ions, Molecules, and Compounds
compound
a molecule containing atoms of two or more
different elements
a. most atoms in the body are joined into
compounds
b. (give two examples)
H2O
NaCl
Ions, Molecules, and Compounds
free radical
an electrically charged ion or molecule
having unpaired electron in its outermost
shell
a. i.e.) superoxide; formed by the addition
of an electron to an oxygen molecule
b. is unstable and destructive to nearby
molecules
??Questions?? Lesson 2
1.
What can generate free radicals in our
bodies?
Exposure to ultraviolet radiation, sunlight, xrays
??Questions?? Lesson 2
2. List disorders and diseases linked to
oxygen-derived free radicals?
Cancer, atherosclerosis, Alzheimer's,
emphysema, diabetes, cataracts, macular
degeneration, rheumatoid arthritis,
increase deterioration with aging
??Questions?? Lesson 2
3. What substances can help minimize
damage from free radicals?
Consuming antioxidants
??Questions?? Lesson 2
4. What forms can be taken as dietary
supplements of these?
Selenium, beta-carotene, vitamins C & E
Intro to Chemistry
Chemical bonds
forces that bind the atoms of molecules and
compounds
1. valence shell
 outermost energy level of an atom that
contains electrons
 determines bonding behavior of the
atom
Chemical bonds
2. octet rule (“Rule of 8’s”)
 The chance that an atom will form a
chemical bond with another atom
depends on the number of electrons in
its valence shell
 atoms interact in such a way so they
will have 8 electrons in their valence
shell; they will interact or bond
Chemical bonds
3 Types of Bonds
1. ionic bond
• attraction between ions of opposite
charges
• bond formed when electrons are
completely transferred from one atom to
another
cation – positive charged ions; protons
exceed electrons
anion – negative charged ions;
electrons exceed protons
Types of bonds
ionic bonds
• ionic bonds are found mainly in teeth
and bones; provides strength
• others are dissolved in body fluids
electrolyte – a compound that
separates into ions when dissolved in
water and can conduct an electric
current
Types of bonds
2.




covalent bonds
a bond involving the sharing of electrons
of two atoms
neither of the combining atoms loses or
gains electrons
the greater the number of electron pairs
shared, the stronger the bond
two atoms share one, two , or three pairs of
electrons
Types of bonds
covalent bonds
 the most common chemical bonds in the
body; form most of body structures
 do not break apart when the molecule is
dissolved in water
Types of bonds
covalent bonds
a. nonpolar covalent bonds: share electrons
equally
b. polar covalent bonds: share unequally;
one atom attracts stronger than the other
Types of bonds
3.
hydrogen bond
• weak bond in which a hydrogen atom
forms a bridge between two electronhungry atoms
• result from attraction of oppositely
charged parts of molecules rather than
sharing of electrons – as in covalent
bonds
Types of bonds
hydrogen bond
• are weak; cannot bond atoms into
molecules
• provide important links i.e.) DNA
Intro to Chemistry
Chemical reactions
•
occur when new bonds are formed and/or
old bonds break between atoms
Chemical Reactions
Types of chemical reactions
synthesis reaction
• larger molecules are formed from
simpler ones; A + B  AB
• anabolism
Chemical Reactions
Types of chemical reactions
decomposition reaction
• complex substances are broken down
into simpler ones; AB  A + B
• catabolism
Chemical Reactions
Types of chemical reactions
exchange reaction
• bonds are both made and broken
• atoms become combined with different
atoms
• AB + C  AC + B ;
• AB + CD  AD + CB
Chemical Reactions
Factors that influence the rate of reactions
1.
temperature
2.
particle size
3.
concentration
4.
catalysts
?Questions?
5. Identify the energy form in use in each of
the following examples:
a. Chewing food. mechanical energy
b. Vision (two types)
i.
ii.
light energy
electrical energy (nerve impulse)
?Questions?
Identify the energy form in use in each of
the following examples:
c. Bending the fingers to make a fist.
mechanical energy
d. Breaking the bonds of ATP molecules
to energize your muscle cells to make
that fist.
chemical energy
??Questions??
6. Define molecule.
A molecule is a combination of two or
more atoms held together by chemical
bonds.
??Questions??
7. Explain the basis of ionic bonding.
Ionic bonds form when electrons are
transferred from one atom to another.
??Questions??
8. How do ionic bonds differ from covalent
bonds?
In covalent bonds, electrons are shared
among the atoms of the molecule; in
ionic bonds, electrons are transferred.
??Questions??
9. What are the hydrogen bonds, and how
are they important to the body?
Hydrogen bonds are fragile bonds
formed when hydrogen atoms bonded to
one molecule (or one part of a single
molecule) are attracted by electronhungry atoms of other molecules (or
other atoms of the same molecule).
??Questions??
10. The two oxygen atoms forming
molecules of oxygen gas that you
breathe are joined by a polar covalent
bond. Explain why this statement is true
or false.
A polar molecule is formed only when the
atoms of the molecule are different and
have different electron-attracting abilities.
Oxygen gas contains two oxygen atoms
and is therefore nonpolar.
??Questions??
Identify each of the following reactions as a
synthesis, decomposition, or exchange
reaction:
a. 2 Hg + O2  2 HgO
b. Fe 2+ + CuSO4  FeSO4 + Cu 2+
c. HCl + NaOH  NaCl + H2O
d. HNO3  H+ + NO3-