Chemistry of Life
The basics of Chemistry
Matter is recycled and rearranged
for living organisms
• Living matter is made up
of different substances.
CO2
• Example of substances:
pure CO2, glucose, pure
salt, H2O…..
glucose
Atoms - Smallest unit of an element (with properties
of that element)
• Nucleus - dense center containing:
– Protons - positively charged
particles
– Neutrons - particles with no
charge
• Electrons (e-) - small, negatively
charged particles that orbit nucleus
in clouds or shells (2, 8, 8)
– Valence - found in outermost
energy level
e-
How many total e-? How
many valence e-? What
element?
A=P=E M=A+N
Atomic number =
Proton number =
Electron number
Mass =
Atomic Number +
Neutrons
Click on image to play video.
Check for Understanding
• How would an element’s identity change if
you took away or added protons?
The 17 essential elements in plants
(autotrophs)…
CHOPKINS Ca Fe Mg B Mn Cu Zn Mo Cl
Carbon, Hydrogen, Oxygen, Phosphorous, Potassium, Iodine,
Nitrogen, Sulfur, Calcium, Iron, Magnesium, Boron, Manganese,
Copper, Zinc, Molybdenum, Chlorine
C HOPKINS Café Managed by my cousin Mo Cline
• 96% of living matter:
C, H , O, and N
• 4% of living matter:
Ca, K, P, S, Na, Cl,
Mg, Fe, and trace
elements
Check for Understanding
Hypothesize as to why these elements are
near the top of the periodic table.
(answer in the left margin)
Atoms, Molecules and Compounds
Molecules and Compounds
• Molecule - 2 or
more elements
joined together by
chemical bonds
• smallest unit of a
compound
Check for Understanding
• What is the name of the
compound in the bottle?
• What is the molecular
formula?
• What is the structural
formula?
• How many molecules of
the substance are in the
bottle?
• How would you calculate
this?
Chemical reactions
6CO2 + 6H2O  C6H12O6 + 6O2
• Lead to changes in substance or matter.
• Occurs when electrons are transferred
between two atoms (lost, gained or
shared)
Octet Rule
• The octet rule is a chemical
rule that states that atoms
with atomic number <20 tend
to combine in such a way
that they each have eight
electrons in their valence
shells.
• 1st Shell holds up to 2
electrons max
• 2nd Shell holds up to 8
electrons
• 3rd Shell holds up to 8
electrons as well
• An Oxygen atom
diagram
Practice
•
•
•
•
•
Al
Mg
S
Ne
N
• Draw the atoms for
the elements listed
at the left and
show the protons,
neutrons and
electrons. Under
the drawing write a
sentence telling me
how many valence
electrons there are.
Drawing Atoms
• As scientists, we want to be
efficient
• Instead of drawing all of the
electron shells, we only
need to draw the valence
electrons
• A Lewis Dot diagram will
make drawing molecules
and compounds easier
Lewis Dot Diagrams
• The inner shells are not
involved in bonding
• Carbon is in group 14, so
that means 4 valence
electrons
• We often write the element
symbol and only the valence
electrons
You try…
What does the Lewis dot
diagram look like for
Oxygen?
What does the Lewis dot
diagram look like for
Sodium?
Hydrogen?
How about Lithium?
Why are they all the same?
Na
H
Li
Ions = electrically charged
matter
• Ions form when electrons are lost or gained.
• Ionic bonds form when a positive ion is attracted
to a negative ion.
Making Salt…Lewis dot style
(Ionic bond) 
positive Na+ attracted to negative Cl -
Click on image to play video.
Covalent
bond = two
atoms sharing
electrons
• “Strong”
• Relatively stable
• Hydrogen, oxygen,
and nitrogen can
readily form
covalent bonds
with carbon.
Hydrogen Bonding
• Weak bonds between
a hydrogen of one
molecule to an
adjacent negative
molecule
• Ex: attraction between
water molecules.
Mixtures
Physical combinations of substances
•
•
•
•
There are several types of mixtures:
solutions
suspensions
Colloids, or colloidal dispersions
Mixtures
Physical combinations of substances
Air = solution
Cytoplasm = colloid
Kool-Aid= solution
Jello = colloid
Blood = suspension
Check for Understanding
Name 3 solutions found in every day life.
Can you think of a suspension?
How about a colloidal dispersion?
Exit Ticket
• Put your FULL NAME, Date and Period on
the BACK side.
• Divide the ½ sheet provided into 3rds.
• In the first box, diagram an atom of
Hydrogen and show the protons, neutrons
and electrons including the valence
electrons
• In the second box, diagram an atom of
Carbon and show the protons, neutrons
and electrons including the valence
electrons
• In the third box, diagram an atom of
Oxygen and show the protons, neutrons
and electrons including the valence
electrons