Matter Matters!
Hydrogen
1 proton
1 electron
Oxygen
8 protons
8 neutrons
8 electrons
Proton
+
Neutron
0
Electron
–
The Periodic Table
K
C
Na Mg
Ca
N
O
P
S
Interactions between atoms
Electrons are key!
• chemical behavior of an atom
depends on # valence electrons
What’s the magic number??
A little more on electrons…
What do you notice about the #
of electrons in each element?
Elements in same row have same # shells &
those in same column have same valence &
chemical properties
Bonds to know…
Little heat needed to break
hydrogen bonds
attraction between + and –
hydrophobic & hydrophilic interactions
interaction with H2O
ionic bonds (transfer of electrons)
Van der Waals forces
Inter or intramolecular attractions (forces
of millions of H2O molecules, Ar2, (HF2))
Sharing of electrons
covalent bonds(nonpolar, polar)
Van der Waal(sum of the
attraction and repulsion forces between
molecules)
Collectively, such
interactions can be
strong, as between
molecules of a gecko’s
toe hairs and a wall
surface
• Chemical reactions are the making
and breaking of chemical bonds
• The starting molecules of a chemical
reaction are called reactants
• The final molecules of a chemical
reaction are called products
• Chemical equilibrium is reached when
the forward and reverse reaction rates are
equal
Energy! & Reactions
What is Energy?
• capacity to do work/supply heat
•Many faces of energy:
• Potential energy (EP) – stored
• Kinetic energy (EK) – motion; aka
thermal energy of molecular motion
• amount of thermal energy in an
object is its temperature
EP high
EP
transformed
to EK
Original EP transformed:
1. Mechanical energy breaks rocks
2. Heat; thermal energy increases rock
Same type of energy
temp
transfer occurs
within atoms and
3. Sound
drives reactions
LawS
of Thermodynamics
• First - Energy NEVER created or
destroyed – changes form
• Second – entropy always increases in an
isolated system
**Entropy – amount of order, disorder, of
chaos in a system (∆S)
Ex: “a neat room is more organized but less stable than a messy
room, which is disorganized but more stable” (Mader page 106)
Spontaneity of Reactions
• Spontaneous! – ONLY when
products have ↓ EP than reactants
AND products have ↑ entropy
Spontaneous nail rusting, wood burning
Nonspontaneous: recharging a battery
• Spontaneous reactions are exergonic
(exothermic); nonspontaneous rxns are
endergonic (endothermic) – require
LARGE amt of energy
Redox reactions
• Paired rxns that involve (-) or (+)
of electrons
**Follow the H’s
in living
systems!**
Oxidation
Atom loses Electron
Remove H’s
Reduction
Atom gains
Electron
Add H’s
• LEO the lion goes GER!
ol x
al e
se i
ie d
ecd
ncu
t i
t c
r z
r e
o
e
o
n
n
Example: Cellular Respiration
Oxidation
Reduction
Glucose is oxidized (loss of electrons) and oxygen
is reduced (gains electrons)
C6H12O6 is high energy molecule and CO2 and H2O are
low energy which is why energy is released
Versatility of Carbon!
• 4 covalent bonds (to itself and other
atoms)
• single, double, triple bonds
•Form straight and branched chains
along with rings
•Nearly endless variety & complexity
•Can form polymers (protein, carbs,
nucleic acids)
• Structural isomers
Drug
Condition
Ibuprofen
Pain;
inflammation
Albuterol
Effective
Enantiomer
Ineffective
Enantiomer
S-Ibuprofen
R-Ibuprofen
R-Albuterol
S-Albuterol
Asthma
STRUCTURE DETERMINES FUNCTION!
Functional Groups-they direct the chemical
behavior of a compound
Has acidic
properties
Acts as a base
Is polar and can form hydrogen
bonds with H2O
Found in sugars At end of carbon skeleton
Within carbon skeleton
Contributes a
negative charge,
can react with
H2O releasing
energy
2 groups can form cross-linking
Methyl (CH3) – can affect the expression of
genes (attached to DNA)
Water, water, everywhere
• H2O molecules form H-bonds
with one another
– +H attracted to –O
creates a sticky molecule
Elixir of Life
• Polarity allows for…
1. cohesion & adhesion
• surface tension, capillary action
2.good solvent
• many molecules dissolve in H2O
• hydrophilic vs. hydrophobic
3.lower density as a solid
• ice floats!
4.high specific heat
• water stores heat
5. high heat of vaporization
• heats & cools slowly
What’s the Water Property?
Direction
of water
movement
Figure 3.3
Adhesion
Two types of
water-conducting
cells
Cohesion
Direction
of water
movement
300 m