The Chemistry of Life
Elements and Water
Matter and Atoms

Matter is any material that has mass and
occupies space.

All materials nonliving and living in the universe
is composed of matter.

All matter is composed of small units called
atoms. The types of atom, their arrangement,
and how they interact with one another gives the
type of matter its specific chemical and physical
properties.

Atoms are composed of subatomic particles each with
their own unique properties. They are:
a. Protons - Positive charge, atomic mass unit of one. Gives the atom
its identity (Atomic Number). Located in the nucleus or center of the
atom.
b. Neutrons – No charge (neutral), atomic mass unit
of one. Their numbers can vary from atom to atom
of the same element. Responsible for forming isotopes. Located in the
nucleus.
c. Electrons - Negative charge, no atomic mass unit. Located
outside of nucleus in regions called orbitals. They are involved
with the process of chemical bonding between atoms.
- can be shared or transferred between atoms in the bonding
process therefore, their numbers can vary between atoms of the same
element.
- If atoms gain or lose electrons they become electrically charged and
are called ions. They are responsible for the reactive chemical
properties of atoms.
Basic Atom Structure
Proton
+ charge
Amu 1
Neutron
No charge
Amu 1
electron orbital
Electron
- Charge
Amu 0
Nucleus composed of protons
and neutrons. Gives the atom its
atomic mass, determined by adding the
number of protons and neutrons
together.
Periodic Table of Elements
•Element is a pure substance made up of one type of atom.
•Elements which are most common in all living things are
Hydrogen (atomic number 1), Carbon (atomic number 6),
Nitrogen (atomic number 7), and Oxygen (atomic number 8).
•These compose the backbone or framework of the molecules
such as proteins, lipids, nucleic acids, and carbohydrates found in
Hydrogen, Carbon, and Oxygen
Other Biologically Important
Elements

Calcium (Ca): Formation of bones and shells in animals, involved
with muscle contraction and neuron activity in animals.

Phosphorous (P): Forms energy storing compounds ATP,
Nucleotides (A,T, G, C, U), and membrane building molecules
(phospholipids).


Sulfur (S): amino acids and protein structure
Sodium (Na): Neuron activity, water balance, and membrane
transport


Potassium (K): membrane transport and muscle activity
Iron (Fe): oxygen transport of red blood cells as a component of
hemoglobin.

Magnesium (Mg): light activated atom component of chlorophyll
molecules.
Chemical Bonding Review
Chemical bonds form to



increase the stability of atoms by filling their outer
most electron energy level.
to do this atoms will transfer electrons ( one atom
will lose electrons and the other atom will gain
electrons) to form ionic bonds
or atoms will share a pair of electrons (each atom
will share one electron for each bond that is created
between them) to form covalent bonds.
Ionic Bonding
Outermost Energy Levels
In order to increase stability, the
Na atom will transfer its outermos
electron to the Cl atom.
Na
Cl
Na
Cl
Sodium (Na)
11
Chlorine (Cl)
17
Sodium (Na)
11
Chlorine (Cl)
17
Protons 11
Neutrons 12
Electrons 11
Charge Neutral
Ion
Neutral
17
18
17
Neutral
Neutral
11
12
10
positive
cation
17
18
18
negative
anion
Stability is achieved because the outer energy levels of both atoms, now ions ar
filled by electrons.
Covalent Bonding
Each pair of electrons
represents the formation
of a covalent bond.
C
Carbon (C)
4
H
Hydrogen (H)
1
H
H
C
H
H
Methane CH4
Stability is again achieved because the outer energy levels of both
atoms, now the outer energy levels are filled by electrons due to sharing
of electron pairs between the atoms!
Periodic Table of the Elements
Five Major Elements in
Humans
Oxygen
Carbon
Hydrogen
Nitrogen
Calcium
O
C
H
N
Ca
Trace Elements
Fe, Zn, Mg, Cu
65%
19%
10%
3%
2%
1%
Water

60 -70% Body Mass
 Polar Molecule
 Solvent
 Reactant / Decomposition
Reactions
 Cohesive Properties
 Surface Tension
 Temperature Buffer
 Thermal Conductance
Water Molecule Structure
and Hydrogen Bonding
Positively charged hydrogen end Covalent bonds between H and O
Negatively charged oxygen end
Hydrogen Bonds
How Hydrogen Bonds Work
• the positive region of one molecule becomes
attracted to the negatively charged region of another
molecule forming Hydrogen Bonds.
• So, the molecules “stick” together  weakly
Water

Water is a molecule that is essential to life as we know it here on
Earth. It is a component of all living things and serves many
functions. Water has many unique properties due to the nature of its
molecular composition.

Water is a polar covalent substance. Although it is formed by
covalent bonds between two atoms of hydrogen and one oxygen
atom, there is an unequal sharing of electrons between the two types
of atoms.

Oxygen is a larger molecule and has a higher attraction for
hydrogen atoms. So, electrons tend to be around the oxygen
atom than the hydrogen atoms.

This results in a slightly negatively charged region of the
molecule where the oxygen atom is located and a slightly
positively charged region of the molecule where the hydrogen
atoms are located.

This produces polarity in the molecule and leads to some
unique properties of water.
Important Properties of Water

High specific heat: It requires much heat energy to raise the
temperature of water one degree Celsius. Important in
regulating the temperature of living things. This results in a
HIGH HEAT OF VAPORAIZATION

This creates a HEAT BUFFER – maintaining homeostasis.

High heat capacity: It requires a long period of time for water
to gain or lose heat energy. Important in regulating temperature,
important to aquatic organisms.

Universal Solvent: Many materials organic and inorganic will
dissolve in water. Important in the role as a transport medium
for living things. Animal blood and the sap of plants are
primarily composed of water with other materials dissolved in it.
Important Properties of Water

Cohesive properties:
Water molecules hydrogen bond together to form
a “film” layer on the surface of water called
surface tension, capable of supporting certain
plants and animals. This property also plays a role
in capillary action (the movement of water up and
through small diameter tubes).

Adhesive properties:
Water molecules due to their polar nature tend to
stick to other substances. This property along
with cohesion is responsible for capillary action
and the formation of a meniscus in a glass tube.
Finally

Water Expands as It Freezes:
The solid form of water is less dense than the liquid,
therefore ice floats!

Most dense at 4 degrees Celsius

This is important in aquatic environments because they
will always freeze from the top surface down. The ice
usually creates an insulating layer from the colder air
temperature, allowing the organisms below the surface of
the ice to survive.

However, this property is also dangerous to organism with
soft tissues. When the water inside their cells freeze, it
expands and destroys the cells. Frost bite in humans is a
result of this property.
Acids, Bases, and Salts
 Acid
 Base
 Salts



H+
OHAnything not an acid or base
2HCl  2H+ + Cl2
NaOH  Na + OH2NaCl  2Na + Cl2
Ionization of Water
Although water is essentially neutral, it can ionize to
a certain extent:
H2O
2 H2O
limited
H+ + OH-
H30+ + OHhydronium
ion
hydroxyl
ion
Ionization of Acids in Water
Acids are substances that dissociate to release H + ions
HCl
limited
H+ + Cl-
Examples of strong acids include stomach acid (HCl), lemon
juice, orange juice
Ionization of Bases in Water
Bases are substances that release OH –
Ions into solution
NaOH
limited
Na+ + OH-
Examples of bases include
Baking soda, antacids, household
ammonia
pH = - log[H+]
Calculating pH
pH = -log[H+]
So if
[H+] = 1 X 10 – 6 ------> pH 6
[H+] = 1 X 10 – 5 ------> pH 5
[H+] = 1 X 10 – 2 ------> pH 2
Litmus Test for Acids
The presence of an acid
turns blue litmus paper red
Litmus Test for Bases
The presence of a base
turns red litmus paper blue
What is Litmus anyways??

a pigment from lichens
that turns red in acid
solutions and blue in
alkaline solutions

It is used as a very
simple acid-base
indicator
Is Your pH Off Balance?

Rings Turn Fingers Green
 Heartburn
 Bloating
 Belching
 Feeling Full after Eating Small Amounts
 Insomnia
 Water Retention
 Migraines
 Constipation
 Diarrhea
 Fatigue
 Burning Sensation on Tongue or in Mouth
 Halitosis
“Modern agriculture and food-preservation
methods have done serious damage to the
human diet. The detrimental effects on the
human body caused by acidic wastes from
processed food and chemical additives are
myriad. Byproducts of the foods we eat,
acidic wastes are the common denominator
in all degenerative diseases. When acidic
wastes accumulate, they can cause organs to
malfunction and degenerate. Balancing the
body's acid-alkaline pH factor is a dynamic
way to improve health. “
Felicia Drury Kliment
pH Buffer
 Stabilizes
the pH level if acids or bases are
introduced to a solution
Example
 Blood if filled with buffers to resist changes
in pH
CO2 + H2O(Blood)  HCO3-1