Composition of Matter
Energy
Solutions
Composition of Matter

Why discuss chemistry in biology class?
 The structure and function of all living things
are governed by the laws of chemistry
Matter
Makes up everything in the universe
 Anything that occupies space and has
mass

 Mass is not = to weight
○ Weight is the pull of gravity on an object (mass
would not change because it is the “quantity of
matter” an object has…
○ You would still be the same “being” on Earth and
on the moon = your mass doesn’t
change…HOWEVER…your weight would be
significantly less on the moon due to the pull of
gravity
Chemical changes in matter
Essential to all life processes
 Living things are made up of the same
kinds of matter that make up nonliving
things
 Understanding changes in matter =
understanding of life processes of
organisms

Elements

Pure substances that cannot be broken
down chemically into simpler kinds of
matter
 90% of mass of all kinds of living things is
composed of combinations of 4 elements:
○ Oxygen (O)
○ Carbon (C)
○ Hydrogen (H)
○ Nitrogen (N)
Chemical Symbols
Atomic Number
Chemical Symbol
Atomic Mass
Name
Atoms

Simplest particle of an element
that retains all of the properties
of that element
 Nucleus = core of atom
○ Made of protons (+) and Neutrons
(no charge)
 All atoms of a given element have same
# of protons
 Atomic # = number of protons
 Electrons
○ High energy particles; negatively
charged; move about nucleus at
very high speeds in “energy levels”
○ First e- level = up to 2 e○ Second e- level = up to 8 e-
Atomic
Energy
Levels
Under natural conditions, most elements do not
exist by themselves
 A compound is a pure substance that is made up
of atoms of two or more elements that are fixed =
water: H2O = chemical formula indicates that the
atoms always combine in a proportion of two
Hydrogen atoms to one Oxygen atom

Compounds
Making Compounds
Stable atom = outermost energy level is
filled
 Most atoms are not stable in natural
state = meaning they tend to
react/combine with other atoms in order
to achieve stability
 Undergo chemical rxns to achieve
stability = chemical bonds are broken;
atoms are rearranged; new bonds are
made


Covalent = 2 atoms
share one or more
pairs of e-

Ionic= one e- gets
transferred from one
atom to another,
resulting in more
stability and giving
both atoms a charge
of + or -
Bonds
You payin’ attention????
What are you to do now?
You are going to complete a “Guided
Notes” (GN) activity…
On page 35 of your textbook, you will
notice that there are 4 objectives listed.
Make a chart/table using the objectives
and take notes from the reading.
Ex:
Objective
Notes

List the three states of
matter, and explain how
matter can change state
• Your notes will go here
• You can bullet
• Leave space so that
you can take notes in
class!
Back to our notes!!!!!
Energy - E
Energy is the ability to do work
 Biological systems need/use: chemical
energy, thermal energy, electrical
energy, and mechanical energy
 Free energy = energy available for work
(cell processes would benefit from this)

Do Right this Very Minute
(DRTVM)

Two Truths and a Lie….
 Take an index card from the front desk
 From the homework (a few nights ago), write




down two truths and a lie about “Energy”
You have 2 minutes!
When 2 minutes are up…you are to find 3
people NOT at your table and try to trick them…
Write down all 3 names on the other side of your
card and write down if they picked the lie or
not…
You have 5 minutes!
States of Matter
Solid, liquid, or gas
 Atoms in constant motion…their
speed determines the state…

 Solid = particles are tightly linked in
definite shape (fixed volume and
shape)
 Liquid = particles are not as tightly
linked (fixed volume)
 Gas = particles move most rapidly;
move freely; little or no attraction to
each other
*Thermal energy must be added to
change a state
Energy and
Chemical
RXNs
Chemical Rxns
Our bodies need a lot of energy…we get
it from breaking down sugars from food
into CO2 and H2O
 Exergonic = chem. rxn where E is
released
 Endergonic = chem. rxn where E is
absorbed

Activation E

What gets you
up and moving
faster???
Really…activation E
the amt of E needed to start a rxn
 Catalysts lower the amt of activation E
necessary for rxn
 Enzymes are important catalysts to
living things – specific to individual
chemical rxns

E movement
Constant flow of
energy into and
throughout living
things
 Many involve
transfer of ebetween atoms

Redox Reactions – These work together
When a compound
becomes “oxidized”
it loses its electrons to
another compound…
When a compound
gains electrons, it
becomes negatively
charged, or reduced.
Solutions (solns)
Solution (soln) – 1+ substances are =
distributed in another substance
 Solute – dissolved substance
 Solvent – does the dissolving (water is the
universal solvent)
 Concentration – measurement of amt of
solute dissolved in a fixed amt of soln
 Saturated soln – no more solute can
dissolve
 Aqueous soln – water is solvent

Dissociation of H2O

Breaking apart of water
Acids and Bases
When an acid is introduced
into a neutral solution, it adds
H+ ions
When a base is introduced
into a neutral solution, it
adds OH- ions
pH
Scale developed to
compare the relative
concentration of
hydronium ions and
hydroxide ions in a
solution
 Ranges from 0 to 14
 0 = very acidic
 14 = very basic
 7 = neutral (water)
See Figure 2-10 on page
42

Buffers
Definitely NOT this guy!

Chemical substances that neutralize small
amts of either an acid or a base added to a
soln