Biology Chapter 2
The Chemistry of Life

Draw an atom of carbon
Agenda: Read Chapter 2 Lessons 2.1 and
2.2 and complete workbook pages 1620
1. Draw an atom of Boron. It has an atomic # of 5 and
an atomic mass of 10. Remember in a neutral
atom the protons = electrons and you calculate the
neutrons by subtracting the atomic number from
the atomic mass.
1.
Differentiate between an element and a compound.
Agenda: Finish reading lessons 2.1 and 2.2 and
completing workbook pages 16-20

Copy this and fill in the blanks:
▪ An atom has a central area called a
________________where the positive
______________ and neutral _____________ are
located. The electrons have a
_______________ charge and are located in the
________________ _____________ which is
outside the nucleus.
Students will be able to
 Describe the structure of an atom
 Differentiate between an element and a
compound
 Describe an isotope
 Explain how and why chemical elements
bond.
Lesson 2.1: The Nature of Matter
WHAT IS MATTER

Anything that has mass
AND takes up space

Solids, Liquids, Gases, and
Plasma
Review
WHAT IS NOT MATTER

Types of energy: heat, light,
sound, electrical and
electromagnetic

Types of forces:
gravitational and magnetic
Lesson 2.1 : The Nature of Matter

Smallest unit of matter
that cannot be divided
and still be the same
element.

Each type of element has
a different number of
subatomic particles
(protons, neutrons, and
electrons)
Review

Nucleus: center of
the atom where
majority of mass is.

Composed of
protons (positively
charged particles)
and neutrons
(neutral particles).
VOCAB: ELECTRON
CLOUD - It is a region
surrounding the nucleus
where one or more
electrons are likely to be
found

Electrons are the negatively charged particles that
reside in a cloud outside the nucleus of the cell.
An atom is the smallest
building block of matter
BUT….
 An atom is made up of even
smaller subatomic particles.
 Protons and neutrons are
about the same size and
weigh 1 AMU.
 Electrons are smaller and
have only about 1/200 the
mass of a proton or neutron.
 Sooooo….you could fit 2,000
electrons into one proton!!!!


Properties of Atomic Particles…

Protons are positive, electrons
are not. Neutrons have no
charge so can’t be bought 

If an atom were the
size of a sports arena,
its nucleus would be
just the size of a pea.

If you compacted all
the atoms in a person
they would fit on the
head of a needle.

Give this a try next
time …

Atomic Number- The
number of protons in
the nucleus of an atom
of a element.
ALL ATOMS OF THE
SAME ELEMENT
HAVE THE SAME
NUMBER OF
PROTONS….
 ALWAYS!!!!!!!


Every element on the
periodic table has a
different atomic
number thus, a
different amount of
protons. Each time you
add an proton, you
change the element.
To calculate the number
of neutrons you subtract
the # or protons from the
Atomic Mass.

Element name:

Element Symbol:

Atomic #:

Atomic Mass:

# Protons:

# Electrons:

#Neutrons:
)
1.
What does the atomic number of an atom represent?
2.
Copy the table and complete it:
Atomic Atomic
#
Mass
rounded
F
9
19
Ar
18
40
Ti
22
48
N
7
14
#P
(+ charge)
#e
(- charge)
#N
(Atomic mass - #P = # of
Neutrons)
)
1.
What does the atomic number of an atom represent?
2.
Complete the following table:
Atomic Atomic
#
Mass
rounded
#P
(+ charge)
#e
(- charge)
#N
(Atomic mass - #P = # of
Neutrons)
F
9
19
9
9
10
Ar
18
40
18
18
22
Ti
22
48
22
22
26
N
7
14
7
7
7
ELEMENTS

Made of a single type of
atom.

All types of elements found
so far are listed on the
periodic table of elements.
COMPOUNDS

Made of TWO or more
types of atoms (elements)
chemically bonded.
Explain which of these are elements and which
are compounds:
1. Hydrogen
2. Water (H2O)
3. Carbon
4. Carbon Dioxide (CO2)
Explain which of these are elements and which
are compounds:
1. Hydrogen (H) ELEMENT
2. Water (H2O) COMPOUND
3. Carbon ( C) ELEMENT
4. Carbon Dioxide (CO2) COMPOUND
What would O2 be???

Neutrons have no charge and
help hold the nucleus
together.

Isotopes are atoms that
have extra neutrons in the
nucleus.

Because neutrons have no
charge adding neutrons does
NOT change the charge of
Isotope…The fat atom is dope!!!!!
the atom. However, it does
change the atomic mass.

Most isotopes are stable,
however some are radioactive
 A radioactive isotope is one in
which the nucleus decays (breaks
down) over time, giving off
radiation in the form of matter and
energy
Uses for Radioactive isotopes
 Geologists can determine the
ages of rocks and fossils by
analyzing the isotopes found in
them.
 Radiation from certain isotopes
can be used to detect and treat
cancer and to kill bacteria that
cause food to spoil.
 Radioactive isotopes can also
be used as labels or “tracers” to
follow the movements of
substances within organisms.
 The atoms in compounds are held together by
various types of chemical bonds.
 Bond formation involves the electrons that surround
each atomic nucleus. The electrons in the outer
energy level that are involved in chemical bonding
are called VALENCE ELECTRONS.
 The main types of chemical bonds are ionic bonds
and covalent bonds but there is also a Hydrogen
bond.
 An ionic bond is formed when one or more
electrons are transferred from one atom to
another.


Remember…all atoms start
out neutral with equal
positive and negative
charges
Protons = Electrons

However, atoms can gain
or loose electrons when
they form an ionic bond.

Ion- an atom that has a
charge because it has
gained or lost an electron
Losing an Electron = Positive ion
Na+
has 11 protons but only 10 electrons
Gaining an Electron = Negative ion
Cl-
has 17 protons but has 18 electrons
 Sometimes electrons are shared by atoms
instead of being transferred, this type of
bonding is called a covalent bond.
 When the atoms share two electrons, the
bond is called a single covalent bond.
Sometimes the atoms share four electrons
and form a double bond. In a few cases,
atoms can share six electrons, forming a triple
bond.
Copy and answer the following questions in
your notebook.
1. Differentiate between an ionic and a covalent
bond.
2. What is an ion and how are positive and
negative ions different?

A MOLECULE is two or more atoms that are
bonded and act as a unit . . . .

Examples are most compounds like H2O
(water) , CO2 (carbon dioxide gas), CH4
(methane gas)
Students will be able to
 Describe the structure of water molecule
 Explain the unique properties of water
 Differentiate between an acid and a basic
(alkaline) solution.

Water is a very unique substance and is
essential to life here on Earth.

Water makes up over 70% of the Earth’s
surface and over 70% of the human body.

It is vital for moving substances through living
organisms.






High surface tension
Cohesion
Adhesion
High Heat Capacity
Lower density as a solid
Universal solvent

Water is a compound made of
2 hydrogen atoms and 1
oxygen atom covalently
bonded (sharing valence
electrons to fill their outer
shell).
Because of the angles of its chemical
bonds, the oxygen atom is on one end of
the molecule and the hydrogen atoms are
on the other.
With 8 protons in its nucleus, an oxygen
atom has a much stronger attraction for
electrons than does a hydrogen atom with
its single proton.
Slightly
positive
charge
Slightly
negative
charge
The polarity (opposite charges on
opposite ends) of water causes
the molecules to attract each
other. This makes water
molecules “Stick” together using
hydrogen bonding.

The hydrogen bonds that
cause the hydrogen end
of one molecule of water
to attract the oxygen
end of another are called
hydrogen bonds.

Hydrogen bonds are
weak and therefore are
broken and reformed
very easily.
COHESION

Cohesion is the attraction
between molecules of the
same substance.

Cohesion causes water molecules
to be drawn together.

This causes surface tension which
allows surface organisms to live on
the top of water
ADHESION

Adhesion is an
attraction between
molecules of different
substances.

Adhesion allows for
capillary action where plant
roots draw water in and up
a plant to the leaves where
photosynthesis occurs.

Heat capacity is the amount
of energy needed to raise
the temperature of a
substance.

Water has a very high heat
capacity so it absorbs large
amounts of heat with only a
small change in the
temperature.

Water is a unique substance in that it expands
when it freezes and the molecules move
farther apart. This causes the density of
water to decrease as it freezes which makes it
float.
Types of
Matter
Matter can be classified into 2
things:
H2O

SUBSTANCES: matter with a
composition that is always the
same.

MIXTURES: matter with a
composition that can vary.
Hydrogen
ELEMENTS

Made of a single type of
atom.

All types of elements found
so far are listed on the
periodic table of elements.
COMPOUNDS

Made of TWO or more types
of atoms (elements)
chemically bonded.
Get your workbook out and get ready to have
pages 16-20 graded.  Happy Hump Day!
List three unique properties of water.
Compare and contrast the following terms
1.
2.

Cohesion and adhesion

A mixture is a material composed of two or
more elements or compounds that are
physically mixed together but not chemically
combined.
HOMOGENEOUS
Mixture where substances are
evenly mixed.
HETEROGENEOUS
Mixture where substances
are NOT evenly mixed



Water is known as the universal solvent
because it is able to dissolve more
substances in nature than anything else
Solution: Uniform
mixture of two or more
substances
Solvent: Substance that
dissolves the other
substance (and is present
in a greater amount)
Solute: Substance that is
dissolved (and is present
in a lesser amount)
 When water is the solvent
it is an aqueous solution
• Some materials do not dissolve
when placed in water, but separate
into pieces so small that they do
not settle out. These mixtures of
water and nondissolved material
are known as suspensions.
• Some of the most important
biological fluids are both solutions
and suspensions.
• Blood is mostly water. It contains
many dissolved compounds, but also
cells and other undissolved particles
that remain in suspension as the blood
moves through the body.
COMPOUNDS
MIXTURES

Have a chemical bond in
which they form a NEW
SUBSTANCE with different
properties than the elements
that made them.

DO NOT have a chemical
bond to hold them together
so they retain their own
physical and chemical
properties.

Can usually only be unbound
by a CHENMICAL CHANGE.

Can usually be separated by
physical means: pulling
apart by hand, boiling,
evaporation.
Physical Properties of Acids and Bases
Review of pH scale and
physical properties of acids and bases

Property
Acids
Bases
Taste
sour
bitter
Smell
Frequently burns nose
Usually no smell (except
NH3)
Texture
Sticky
Slippery
Reactivity
Reacts with metals
Reacts with oils and fats

In aqueous solutions some water molecules break apart into ions
 In pure water, about 1 water molecule in 550 million splits to form ions
in this way.
 Because the number of positive hydrogen ions produced is equal to
the number of negative hydroxide ions produced, pure water is
neutral.
Any compound that donates H+ ions to a solution is called an
ACID
 Any compound that removes H+ ions from a solution is called a
BASE


pH scale is used to describe how acidic or basic a compound
is based on the percentage of Hydrogen ions (H+) and
Hydroxide ions (OH-)
pH Neutral = H+ ions = OH- ions

Describe the pH scale and explain how acids
and bases are different.
 Each step on the pH
scale represents a
factor of 10. For
example, a liter of a
solution with a pH of
4 has 10 times as
many H+ ions as a
liter of a solution
with a pH of 5.
For example: Coffee with a pH of 5.0 has
100x’s (10 X 10) more H+ than pure water
with a pH of 7.0.
 In order to maintain homeostasis the fluids within most cells in the
human body must generally be kept between 6.5 and 7.5. If it goes
lower or higher, chemical reactions that take place within the cells
can be affected.
 One of the ways that organisms control pH is through dissolved
compounds called buffers, which are weak acids or bases that can
react with strong acids or bases to prevent sharp, sudden changes
in pH.

Describe the pH scale and explain how acids
and bases are different.

Be sure to turn your lab sheet in to be graded
at the end of the class period today.

Students who did not complete the notes on
pH assigned for homework last night MUST
write -20% on their lab form.

Explain what elements carbon bonds with to
make up life’s molecules.

Explain what elements carbon bonds with to
make up life’s molecules.

Carbon can bond with many elements,
including hydrogen, oxygen, phosphorous,
sulfur, and nitrogen to form molecules of life.

The organic (organic means they contain
carbon) compounds in living cells that are
made of thousands or even hundreds of
thousands of smaller molecules.

Macromolecules are formed through a
process called polymerization where large
molecules are built by joinging together
smaller ones.

The smaller units, monomers, are joined
together to form larger ones, polymers.
Macromolecule
Type
Carbohydrates
Lipids
Nucleic Acids
Proteins
Structure
Function
Examples

Structure: Compounds made of carbon,
hydrogen, and oxygen atoms in a 1:2:1 ratio.

Function: Carbohydrates serve as the main
source of energy for most living things and also
for structural support.

Examples: table sugar (sucrose), bread, pasta,
fruits (fructose)

Structure: made of carbon and hydrogen
atoms.

Function: Lipids can be used to store energy
but work primarily to support structure and
can provide waterproof properties.

Examples: fats and oils

Structure: macromolecules that contain H, N, C
, and phosphorus. Made of nucleotides,
monomers, that combine to form the polymers.
Nucleotides include a phosphate group, a
nitrogenous base, and a 5 carbon sugar.

Function: Nucleic acids store and transmit
hereditary or genetic information.

Examples: DNA, RNA

Structure: Macromolecules that contain nitrogen,
carbon, hydrogen and oxygen. Proteins are polymers
of molecules called amino acids.

Function: Proteins are responsible for MOST
important cellular functions including, controlling
rates of reactions, regulating cell processes, cellular
structures, transporting substances into or out of
cells, and to fight disease.

Examples: Amino Acids, all meats, beans, eggs, most
animal products

Proteins make things happen 

List the 4 main macromolecules and give
their main function

Name the 4 main elements that make up 95%
of an organism.

What is the difference between sucrose,
glucose, and galactose

A glucose molecule, C6H12O6
The chemical formula for sucrose is C12H22O11

What happens to chemical bonds during
chemical reactions?
Workbook pages 21-28 are due Friday


EVERYTHING that happens in an organism –
it’s growth, it’s interaction in the
environment, it’s reproduction, and even it’s
movement – are based on chemical reactions.

A chemical reaction (VOCAB) is a process
that changes or transforms, one set of
chemicals into another.
An important chemical reaction in your bloodstream enables carbon
dioxide to be removed from the body.
As it enters the blood, carbon dioxide (CO2) reacts with water to produce
carbonic acid (H2CO3), which is highly soluble.
This chemical reaction enables the blood to carry carbon dioxide to the
lungs.
In the lungs, the reaction is reversed and produces carbon dioxide gas,
which you exhale.

Law of Conservation of Energy: Energy
cannot be created or destroyed . . .it is
transformed.

Law of Conservation of Mass: The mass of
the reactants is always equal to the mass of
the products in a chemical reaction.
These are NOT in your book 

Theories explain why
something happens in
nature.

Laws don’t explain
anything they just
state what will happen.

Ex: Theory of Plate
Tectonics

Ex: Law of
Conservation of Mass

Reactants (VOCAB)

Products (VOCAB)

The elements or
compounds that go
INTO the chemical
reaction

The elements or
compounds that come
OUT OF the chemical
reaction
Reactants
Products
EXOTHERMIC
VS.

Chemical reactions that
RELEASE energy are called
Exothermic reactions. They
usually react on their own
or spontaneously.

They will feel warm or hot
when they occur and may
release light and sound..
ENDOTHERMIC

Chemical reactions that
ABSORB energy are called
Endothermic reactions.
Require a source of energy
to occur.

They will feel cool or cold
when they occur.
 An example of an energy-releasing reaction is the
burning of hydrogen gas, in which hydrogen reacts
with oxygen to produce water vapor.

 The energy is released in the form of heat, and
sometimes—when hydrogen gas explodes—light
and sound.


The reverse reaction, in which water is changed into
hydrogen and oxygen gas, absorbs so much energy that
it generally doesn’t occur by itself.
2H2O + energy  2 H2 + O2

The only practical way to reverse the reaction is to
pass an electrical current through water to decompose
water into hydrogen gas and oxygen gas.

Thus, in one direction the reaction produces energy,
and in the other direction the reaction requires energy.
 Every organism must have a source of energy to carry
out the chemical reactions it needs to stay alive.
 Plants get their energy by trapping and storing the
energy from sunlight in energy-rich compounds.
 Animals get their energy when they consume plants or
other animals.
 Humans release the energy needed to grow, breathe,
think, and even dream through the chemical reactions
that occur when we metabolize, or break down, digested
food.

Chemical reactions that release energy do
not always occur spontaneously.

The energy that is needed to get a reaction
started is called activation energy (VOCAB)
 The peak of each graph represents the energy needed
for the reaction to go forward.
 The difference between the required energy and the
energy of the reactants is the activation energy.
Activation energy is involved in chemical reactions
whether or not the overall reaction releases or absorbs
energy.

http://www.youtube.com/watch?v=yvyHVA1
Ww_M

Catalysts (VOCAB) are substances that
speed up the rate of a chemical reaction.
 Catalysts work by lowering a reaction’s
activation energy.

Enzymes (VOCAB) are proteins that act as
biological catalysts.

Some chemical reactions that make life possible are
too slow or have energy levels too high for practical
use.

These reactions are made possible by the catalysts
made by cells called enzymes.

For example, the reaction in which carbon dioxide
combines with water to produce carbonic acid is so slow
that carbon dioxide might build up in the body faster
than the bloodstream could remove it.

Your bloodstream contains an enzyme called carbonic
anhydrase that speeds up the reaction by a factor of 10
million, so that the reaction takes place immediately and
carbon dioxide is removed from the blood quickly.
 Enzymes are very specific, generally catalyzing only
one chemical reaction.
 Part of an enzyme’s name is usually derived from
the reaction it catalyzes.
 Carbonic anhydrase gets its name because it also
catalyzes the reverse reaction that removes water
from carbonic acid.
 For a chemical reaction to take place, the
reactants must collide with enough energy so
that existing bonds will be broken and new bonds
will be formed.
 If the reactants do not have enough energy, they
will be unchanged after the collision.
 Enzymes provide a site where reactants can be
brought together to react. Such a site reduces
the energy needed for reaction.
 The reactants (what goes
in to the chemical reaction)
of enzyme-catalyzed
reactions are known as
substrates.
 For example, the enzyme
carbonic anhydrase
converts the substrates
carbon dioxide and water
into carbonic acid (H2CO3).
 The substrates bind to a site on the enzyme
called the active site.
 The active site and the substrates have
complementary shapes.
 The fit is so precise that the active site and
substrates are often compared to a lock and key.
 Temperature, pH, and regulatory molecules are all
factors that can affect the activity of enzymes.
 Enzymes produced by human cells generally work best
at temperatures close to 37°C, the normal temperature
of the human body.
 Enzymes work best at certain pH values. For example,
the stomach enzyme pepsin, which begins protein
digestion, works best under acidic conditions.
 The activities of most enzymes are regulated by
molecules that carry chemical signals within cells,
switching enzymes “on” or “off” as needed.
1. What is the purpose of an enzyme?
2. Compare and contrast endothermic and
exothermic reactions
3. What 3 things can affect how an enzyme
works?

http://www.youtube.com/watch?v=ok9esggz
N18

Get your workbook out and get ready to have it
graded. Remember pages 21-28 need to be
completed.

Then get a laptop and login to IRCHS website. Go to
staff directory, search my name and locate my
website.

On my website, go to Biology, then Unit Study Notes,
then Unit 3 . . . Scroll down to the Enzyme webquest
link and click on it. You will use this to answer the
questions for the webquest – due today .
Copy the following questions in your notebook . .
this is your study guide for the quiz on Thursday.
1. Know the subunits, function, and examples of
each of the 4 main macromolecules.
2. Know the difference between an endothermic
and exothermic reaction
3. Know the definition of a reactant, product,
catalyst, enzyme, activation energy, substrate
4. Identify the components of an enzyme complex.
5. Know the 3 things that can affect how well an
enzyme works.

Get your calculators out.

Count out 50 toothpicks and place them in a
loose pile on your desk – spread out.

I will put the timer on the board and we will
start the activity 

http://www.online-stopwatch.com/

http://www.youtube.com/watch?v=_5TaS0VaDo

Copy the columns and match the subunit
with the correct macromolecule
Macromolecules
Subunits
Lipids: ______________________
A. Nucleotides
Proteins:_____________________
B. Amino acids
Carbohydrates:________________
C. Triglycerides
Nucleic Acids:_________________
D. Monosaccharides
1.
Open your workbook to page 21. We will go
over pages 21-28
2.
Then we will go over the study guide
Copy the following questions in your notebook . .
this is your study guide for the quiz on Thursday.
1. Know the subunits, function, and examples of
each of the 4 main macromolecules.
2. Know the difference between an endothermic
and exothermic reaction
3. Know the definition of a reactant, product,
catalyst, enzyme, activation energy, substrate
4. Identify the components of an enzyme complex.
5. Know the 3 things that can affect how well an
enzyme works.