•Unit 3
• The
Chemistry of Life
• Unit
Objective:
• To
identify the carbon-based organic
molecules of life and understand the roles
they play in life processes.
Only copy down underlined material.
Everything else is there for support.
•What’s Important About the Nutrition
Label?
• What
• Why
does the label tell you?
is this important?
•What Are Organisms Made Of?
•
Every organism is different depending upon it’s role or
needs but there are basic molecules that are universal.
•The Basic Compounds of Life.
•
Regardless of the amount, most organisms use these
elements to form the macromolecules of life.
1.
2.
3.
4.
•
These are the fundamental molecules of life that you will
be required to know.
•
•
Fats
Proteins
Sugars
Nucleic Acids.
These carbon-based molecules are known as Organic Compounds.
Another molecule you will learn about in this mini-unit
is water.
•Essential Questions
•
•
How does hydrogen, carbon, and oxygen combine to form
molecules that participate in living systems?
What do these molecules do to support life?
•Objectives
•
•
•
•
•
To review/identify what makes up matter.
To know the elements that form most organic molecules.
To review/understand why atoms form bonds.
To understand how and why these bonds are essential for
life by forming the carbon-based organic molecules of life.
This information will help you soon be able to explain how
these molecules participate in important processes in living
things.
•Vocabulary
• Atoms
• Element
• Valence
electrons
• Compound
• Molecule
• Ion
•Before You Learn About the Organic Macromolecules…
• You
must understand that all bigger molecules
are built of smaller pieces.
Everything of atoms…
• Sometimes arranged into basic molecules.
•
• These
smaller pieces are called…
• These
will sometimes be called…
•
• What
•
OR
is a subunit?
Something that is combined with other subunits to
build something bigger.
•Atoms
• Every
living and nonliving thing is made of
matter.
• Matter is anything that has mass and takes up
space.
All matter is made of very
small particles called atoms.
• An atom is the smallest unit
of matter that cannot be
broken down by chemical
means.
• These are the most basic
subunit of matter & life.
•
•Atoms
• The
atom is composed of three main types of
smaller particles.
• Protons:
positively
charged particles.
• Neutrons: particles
with no charge.
• Electrons: negatively
charged particles.
•Atoms
• The
particles are in two
specific areas:
The nucleus.
• The electron cloud.
•
• Protons
and neutrons
are in the nucleus.
• Electrons are in various
energy levels contained
in the electron cloud
around the nucleus.
What are the parts of an atom?
B
C
A
D
•How Is an Atom Built?
Find carbon on the periodic table.
• This is the information for the element CARBON
• Notice its row and column.
•
C
O
L
U
M
N
ROW
• Every
box represents a different element.
An element is any quantity of a substance that is 100%
the same type of atom.
• Being the same type means they have the same # of
protons.
•
•
Ex: Diamonds are always the element carbon, regardless of the
size, because every atom has 6 protons.
•CHNOPS: What are the Most Abundant
Elements in Biology?
•
•
The six highlighted below are the most abundant elements in the
bodies of most biological organisms.
Mark these in your Periodic Table.
•Reading the Periodic Table
• Atomic
Number
• Symbol
• Name
• Atomic
Mass
•Atomic Numbers, Mass, Electrons…
• The
boxes give a lot of information.
• How do you know how many protons,
electrons, and neutrons an element has?
• It’s all based upon the atomic number found in
the periodic table.
• Atomic
# = # protons
• # electrons = # protons
• # neutrons = atomic mass (whole) - # protons.
•IONS: What Happens When an Atom
Gains or loses an Electron.
• Ions
are atoms that gain or lose electrons.
This results in unequal numbers of p+ & e-.
• These particles are now considered charged, or
ions.
• Why? Some elements steal electrons.
•
•Formation of Ions: Count the p+ & ebefore & after the exchange…
Anion:
A negatively
charged ion.
Cation:
A positively
charged ion.
+
Na
Cl
Sodium
Before
After
Chlorine
Before
After
Protons
+11
+11
Protons
+17
+17
Electrons -11
-10
Electrons -17
-18
Total
+1
Total
-1
0
0
•Special Circumstance: Isotopes
Elements
• Recall, elements are all the same type of atom because
every atom has the same number of protons.
•
•
•
For example, every atom for any amount of the element
carbon has six protons.
There are several types of carbon though.
Atoms of an element can have different numbers of
neutrons.
• Isotopes
are atoms of elements that have a
different number of neutrons.
•
Isotopes create challenges and benefits because bonds
form differently and they are usually radioactive to
various degrees.
•Isotopes
• Because
Isotope atoms have
the same number of
protons, and also electrons,
isotopes have the same
chemical properties.
• The extra neutrons makes
the isotope radioactive.
•The Numbers Really Matter
• The
numbers represent an atom’s proton,
neutron, and electron number when it is unbounded and electrically neutral.
• Atoms are rarely like this, stable, in nature.
• Mainly because the electrons are always flying
around.
electron
•The Energy Levels
• Atoms
are usually represented as a nucleus
surrounded by rings.
• The rings are energy levels.
• The row (going from left to right) tells you
how many rings the atom has.
Hydrogen is in the 1st row = one ring
• Nitrogen is in the 2nd row = two rings
•
• Shown
• These
to the right.
are the atom’s energy levels.
•The Outer Ring… The Valence Shell
• The
outer ring holds the valence shell
electrons.
• For most groups of atoms, you can determine
the # of valence shell electrons from the
column it’s in.
How many does this element have?
• What element is it?
•
• Knowing
the valence shell is important
because in the valence shell bonding
happens.
•Reading the Periodic Table
• The
Column tells you how
many electrons in the outer
shell (valence electrons).
• The Row tells you how many
rings (Energy levels)
•Concept Check
• On
your handouts, complete the blank atom
for the element carbon.
•
Draw the:
• Correct
# of electrons
• Correct # of electron in the valence shell
• Correct # of protons
• Correct # of neutrons
•
Put them in the correct places.
•Try It Again…
• Try
•
Phosphorus
Draw the:
• Correct
# of electrons
• Correct # of electron in the valence shell
• Correct # of protons
• Correct # of neutrons
•
Put them in the correct places.
•Chemical Bonds
•
•
•
•
•
•
Remember, electrons are orbiting the nucleus in the region
called the electron cloud... In different energy levels.
The outer most edges of this cloud is called the valence shell.
There is a strict rule for how many electrons are in this valence
shell & each group is slightly different.
It’s based upon the group the element is in.
Group 1A (hydrogen, etc.) has one valence electron.
Group 2A (beryllium, etc.) has two.
•Chemical Bonds
•
•
•
•
•
Remember, electrons in the outermost level, or shell, are called
valence electrons.
When more than one atom combines, a force called a chemical
bond holds them together in the valence shell.
There are three types of bonds that you need to know.
• Covalent bonds
• Ionic bonds
• Hydrogen bonds.
The RULE OF BONDING = Atoms tend to combine with each other
such that eight electrons will be in the valence shell.
The reason is stability!
•Valence electrons:
•Chemical Bonds, continued
• Every
other element will bond with other
elements to get to 8 valence electrons.
• Chemical bonds form between groups of
atoms because atoms become stable when
they have eight electrons in the valence shell.
• When atoms of different elements combine, a
compound forms.
• A compound is a substance made of the
bonded atoms of two or more elements.
•Common Compounds
• Ammonia
(NH3)
• Water (H2O)
• Methane (CH4)
• Glucose (C6H12O6)
• Salt (NaCl)
•Ionic Compounds
Ionic Bonding
• Atoms can sometimes achieve a stable valence level by
losing or gaining electrons.
• When this happens, the charge of the atom changes
slightly and an ion is formed.
•
An ion is an atom or group of atoms that has an electric
charge because it has gained or lost electrons.
Opposite charges attract.
• The attractive force between oppositely charged ions is
an ionic bond.
•
•How Do You Know How Many Electrons
Get Exchanged?
• It
is all based upon the number of valence
electrons for the element in its basic form.
• The metals on the left usually give electrons
because they are closer to 8 if they lose a few.
• The non-metals on the right usually gain
electrons because they will achieve 8 if they
gain just a few.
•
•
These opposite charges attract each other!
What happens
when the
electron leaves
sodium and
goes to
chlorine?
The electrons
no longer equal
the protons and
they form into
oppositely
charged ions,
like minimagnets.
•Find These Elements on you Periodic Table
Gains eLoses e-
Carbon
Gains or
Loses eHow close are these elements to achieving 8 in their valence
shell?
Is it faster to gain a few or lose a few?
The numbers of e- gained/lost are variable & correspond to
how many they need.
What about carbon?
•Try Drawing Example B1: Sodium &
Chlorine
•Formation of Ions: Count the p+ & ebefore & after the exchange…
+
Na
Cl
Sodium
Before
After
Chlorine
Before
After
Protons
+11
+11
Protons
+17
+17
Electrons -11
-10
Electrons -17
-18
Total
+1
Total
-1
0
0
•How Do You Show the Bonds?
• Ionic
Bohr Model
Or…
Lewis Structure
•Try Drawing Example B2: Magnesium &
Iodine
Since Magnesium
donated 2 electrons
what should its charge
be?
Since each chlorine
received one electron
what should each
charge be?
+2
When Magnesium loses its
outer electrons it exposes
its next lower energy level,
which happens to have 8
electrons.
I
I
-1
-1
•Chemical Bonds, continued
Covalent Bonding
• One way that atoms bond is by sharing valence
electrons to form a covalent bond.
•
A molecule is a group of atoms held together by
covalent bonds.
•
A water molecule, H2O, forms when an oxygen atom
forms covalent bonds with two hydrogen atoms.
•Poor Oxygen…
•
•
•
•
•
Ah, I’m sad because my valence shell isn’t filled.
If there was only some way to get more.
Wait. Hey Buddy. If we shared some electrons, then we could both have
8…kinda.
Now we both can have eight!
Sometimes… and that’s enough to form a covalent bond.
•How Do You Show the Bonds?
• Covalent
Bohr Model
Or…
Lewis Structure
•Illustrate Ionic & Covalent Bonding
•2
minutes…
• With Lewis Structures, complete C2.
•Polarity
•
•
•
•
•
Polar Molecules result when the resulting molecule has partial
charges on opposite ends because of electrons are not shared
equally.
In some covalent molecules, the electrons are shared equally
between the atoms in the molecule.
In some covalent bonds, the shared electrons are attracted more
strongly to one atom than to the other.
It’s due to electronegativity (something you don’t need to know
right now).
As a result, one end of the molecule has a partial negative
charge, while the opposite end has a partial positive charge.
•Same Atoms sharing electrons equally
Make it Non-Polar
-
-
-
-
-
-
+
+
-
-
-
-
•Not Sharing Electrons Equally Results in
Polar Molecules
-
-
Partially –
-
-
Partially +
The electrons
spend less time
on this side of
water
-
-
-
The electrons
spend more
time on this
side of water.
•Not Sharing Electrons Equally can sometimes
be 2 atoms, sometimes more.
-
-
Partially +
-
-
-
-
-
Partially -
•Hydrogen Bonding
•
A hydrogen bond is a
bond that forms
between the positive
hydrogen atom of one
molecule and the
negative pole of
another molecule.
Represented as
dashed lines.
We will see these
again…
•Polarity, continued
Hydrogen Bonds
• When bonded to an oxygen, nitrogen, or fluorine atom, a
hydrogen atom has a partial positive charge nearly as great
as a proton’s charge.
• It attracts the negative pole of other nearby molecules.
• This attraction is stronger than attractions between other
molecules, but not as strong as covalent bonds.
• However, hydrogen bonding plays an important role in many
of the molecules that make up living things.
•Polarity of Water
• Water
is a molecule that shares electrons
unequally.
• Oxygen attracts the electrons more than
hydrogen does.
• This causes the oxygen atom to be, on
average, more negative than the hydrogen,
which tend to be more positively charged.
2δ-
δ+
δ+
•Polar Molecules:
Water
The polarity of
water makes it
able to form
polar bonds
with other water
molecules,
called2δhydrogen
bonds,
due to
δ+
δ+
the negative
oxygen and the
positive
hydrogen.
•Special Circumstance: Noble Gasses
• Some
atoms won’t bond with other elements
because they already have 8 valence
electrons.
• These are called Nobel Gasses.
• These are group 8A (all the way on the right).
•Concept Review
• What
are the three subatomic particles?
• Where are they located?
• Do electrons go anywhere they want?
• What is an isotope?
• What is an ionic bond?
• What is a covalent bond?
• What makes a molecule polar?
•Why Bonding is Important?
• The
reason why we review bonding is
because the ability of atoms to interact with
each other allows for them to build larger
molecules.
• Depending on the types of numbers of atoms
an almost limitless number of molecules and
compounds can be formed, each with its own
unique properties.
• These build on one another to make life
possible.
•Closure…
• Questions?
• What
did you learn today?
• Reflect in your warm ups…
•Now
• Get
into your groups.
• Together you will use your notes and books
to complete the worksheet provided so I
know you understand the basic concepts of
bonding.
• Due next class period.
•Atomic Models
• There
are a variety of ways to represent an atom…
• It really depends on why you are showing the
atom that will determine how you show it.
Electron-Dot Diagrams = show electrons & protons for
ions & bonding
• Space filling models = show how the molecule looks in
3D
• Bohr’s model = shows all electrons to represent
energy levels. WHAT YOU BUILT
• Lewis structures = shows valence electrons (only) for
bonding
•
•Lots of Atoms
• Which
right?
one’s
•How to Represent an Atom.
• Standard
Electron Dot Diagram.
• Space-filling (O2)
• Bohr’s Model
• Lewis Structure
•Lewis Dot Structures
Shows only the electrons that participate in bonding.
•Bohr’s
V.
Rutherford’s
-
-
-
-
+++
+++
-
+++
+++
-
-
-
-
-
-
Different Orbits
Same Orbit
•Where electrons actually are…Schrödinger
•
Q: Can you
identify
where the
electron
is?
+++
+++
•
A: No!
because
the
electrons
never stop
moving!
•Group Section Questions: Answer these questions together as a
group. Answers only. You have 10 minutes. We will cover these
answers together at the end of class.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
A(n) _________ is the smallest unit of matter that cannot be broken down by
chemical means.
Identify the 3 sub atomic particles of atoms and their locations in words or in an
illustration.
A(n) _________ is a substance made of only one kind of atom that has the same
number of protons.
Locate oxygen and tell me how many protons, neutrons, and electrons it has.
(use your periodic table…the atomic number is extremely useful).
Atoms are most stable when they have 8 electrons in their ______ ______.
How many protons, electrons, neutrons, energy levels, and valence electrons
does carbon have?
Name two ways that atoms can form bonds (combine to become more stable).
Describe polarity and a popular polar molecule.
Explain how polarity can cause salt & sugar to dissolve in water.
Water is an example of a compound that is held together by ________ bonds.
Atoms gain or lose ___________ to form ions.
The opposite ends of a polar molecule have ___________ charges.
A(n) _______ ______ is a weak chemical attraction between polar molecules.
•Group Section Questions: Answer these questions together as a
group. Answers only. You have 10 minutes. We will cover these
answers together at the end of class.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
atom is the smallest unit of matter that cannot be broken down by
A(n) _________
chemical means.
Identify the 3 sub atomic particles of atoms and their locations in words or in an
illustration.
p+, e-, n0… p+, n0 in nucleus, e- in electron cloud
A(n)element
_________ is a substance made of only one kind of atom that has the same
number of protons.
8
8
8
Locate oxygen and tell me how many protons, neutrons, and electrons it has.
(use your periodic table…the atomic number is extremely useful).
valence _________.
shell
Atoms are most stable when they have 8 electrons in their __________
6
6
6
2
4
How many protons, electrons, neutrons, energy levels, and valence electrons
does carbon have?
Name two ways that atoms can form bonds (combine to become more stable).
Ionic (swapping electrons), covalent (sharing electrons) When a molecule has a partial + & partial –
Describe polarity and a popular polar molecule. charge. Water is polar and can dissolve the
ions & polar molecules in sugar & salt
Explain how polarity can cause salt & sugar to dissolve in water. because of polarity.
covalent bonds.
Water is an example of a compound that is held together by ___________
electrons to form ions.
Atoms gain or lose _______________
The opposite ends of a polar molecule have opposite
___________ charges.
bond is a weak chemical attraction between polar molecules.
A(n)hydrogen
__________ _________
•Homework
• Build
1.
2.
3.
4.
a Phosphorus Atom
Find the atom on the periodic table
Determine the number of protons, electrons, & neutrons.
Determine the energy levels.
Fill in the electrons, protons, & neutrons.
• Illustrate
•
Show the electron swapping with an arrow.
• Illustrate
•
the Ionic Bond of NaCl
the compound H2O
Show how it is a polar molecule.
• Show
hydrogen bonding between 2 H2O
molecules
•Homework
• Build
1.
2.
3.
4.
a Phosphorus Atom
Find the atom on the periodic table
Determine the number of protons, electrons, & neutrons.
Determine the energy levels.
Fill in the electrons, protons, & neutrons.
• Illustrate
•
Show the electron swapping with an arrow.
• Illustrate
•
the Ionic Bond of NaCl
the compound H2O
Show how it is a polar molecule.
• Show
hydrogen bonding between 2 H2O
molecules
•Homework
• Build
1.
2.
3.
4.
a Phosphorus Atom
Find the atom on the periodic table
Determine the number of protons, electrons, & neutrons.
Determine the energy levels.
Fill in the electrons, protons, & neutrons.
• Illustrate
•
Show the electron swapping with an arrow.
• Illustrate
•
the Ionic Bond of NaCl
the compound H2O
Show how it is a polar molecule.
• Show
hydrogen bonding between 2 H2O
molecules
•Homework
• Build
1.
2.
3.
4.
a Phosphorus Atom
Find the atom on the periodic table
Determine the number of protons, electrons, & neutrons.
Determine the energy levels.
Fill in the electrons, protons, & neutrons.
• Illustrate
•
Show the electron swapping with an arrow.
• Illustrate
•
the Ionic Bond of NaCl
the compound H2O
Show how it is a polar molecule.
• Show
hydrogen bonding between 2 H2O
molecules
•In-class Exercise: Check For
Understanding
•
To check that you’ve been paying attention and you understand
• Build
1.
2.
3.
4.
a Phosphorus Atom
Find the atom on the periodic table
Determine the number of protons, electrons, & neutrons.
Determine the energy levels.
Fill in the electrons, protons, & neutrons.
• Illustrate
the Ionic Bond of NaCl
• Illustrate the compound H2O
• Show hydrogen bonding between 2 H2O
molecules
n0 = 15
p+ = 15
•Section Questions: Answer these questions in your notebooks.
Write complete sentences for them all.
Section 2.1
1.
A(n) _________ is the smallest unit of matter that cannot be broken down by chemical means.
2.
Identify the parts (particles) of atoms and their locations in words or in an illustration.
3.
A(n) _________ is a substance made of only one kind of atom that has the same number of protons.
4.
Name one element & how many protons, neutrons, and electrons it has. (use the back of the book for
reference…the atomic number is extremely useful).
5.
Atoms are most stable when they have eight electrons in their _________ _________.
6.
How many protons, electrons, neutrons, energy levels, and valence electrons does carbon have?
7.
Name two ways that atoms can form bonds (combine to become more stable).
8.
Explain how charges cause salt & sugar to dissolve in water.
9.
Water is an example of a compound that is held together by _____ bonds.
10.
Atoms gain or lose ________________ to form ions.
11.
The opposite ends of a polar molecule have _____________ charges.
12.
A(n) ___________ ___________ is a weak chemical attraction between polar molecules.
Section 2.2
1.
List & describe the 4 properties of water that make life on Earth possible.
2.
An example of a substance that heats more slowly than many other substances is ______.
3.
Why does water float?
4.
An attraction between particles of the same substance is called_______, while an attraction between
particles of different substances is called ________.
5.
Differentiate between acids & bases.
6.
A solution that contains more hydronium ions than hydroxide ions is ____ and has a pH below _____.
7.
What is a buffer & what is it’s role in maintaining homeostasis?
•Summary
•
All matter is made up of atoms. An atom has a positively
charged nucleus surrounded by a negatively charged
electron cloud.
•
Chemical bonds form between groups of atoms because
most atoms became stable when they have eight electrons in
the valence shell.
•
Polar attractions and hydrogen bonds are forces that play an
important role in many of the molecules that make up living
things.
http://www.flw.com/datatools/periodic/118.htm
•Atoms, continued
•
•
•
•
•
99+% of the atom’s mass is made up
of the protons and neutrons found in
the nucleus.
The other <1% of the atom’s mass is
found by adding up all the individual
electrons.
The nucleus takes up less than 1% of
the atom’s physical space… its
volume, however.
99+% of the atoms actual space is the
electron cloud where the electrons are
zooming around at nearly the speed
of light.
Technically, we are 99% empty space!
Electron Cloud
Nucleus
•Quick Facts. Put an atom into perspective.
• If
you used a stadium to model and atom…
The Houston Astrodome (Home of the Houston
Astros…a baseball team) seats 60,000 fans, covers 9
acres and the dome rises to a height of 200ft.
++
• If you could blow up an +atom
to the size of this stadium
+++
a basketball could represent the volume of an atom's
nucleus.
• The rest of the open area is the volume of where the
electrons, maybe the size of tiny BB’s, would be
constantly flying around at speeds approaching the
speed of light through the electron cloud in their
orbitals.
•
•Technically, We Are 99.9% Empty Space?
• Why
do we
appear solid?
•Why Do Things Feel Solid?
We actually feel very little that is solid.
What we feel is the interpretation of what
solid is because of the electron clouds pushing
away from one another.
Which segues into the next part of the lesson.