2-2 Properties of Water
The Chemical Context of Life
KEY CONCEPTS:
Matter consists of chemical elements in pure form
and in combinations called compounds.
An elements properties depend on the structure of
its atoms
The formation and function of molecules depend on
chemical bonding between atoms
Chemical reactions make and break chemical bonds.
Atoms are
basic unit of MATTER
the ________________:
2-2 Properties of Water
PROTONS (+)
______________
NEUTRONS
______________
are found in
______________
NUCLEUS
ELECTRONS
(
)
______________
orbit
outside nucleus in
___________________
energy levels
____________________
2-2 Properties of Water
Atoms differ in numbers of
PROTONS
_______, NEUTRONS
________,&ELECTRONS
_______
2-2 Properties of Water
Atoms that have gained
or lost electrons have an
electric charge and
_____________
are called
IONS
__________
They are written
with a + or –
next to their
symbol
Na
+
Cl
2-2 Properties of Water
Atoms/ions important for
living things
Used to make
bigger molecules
1.____________
Carbon - C
2.____________
Oxygen - O
3.____________
Hydrogen - H
4.____________
Nitrogen - N
5.____________
Sulfur - S
6.____________
Phosphorus - P
Ions = electrically
charged atoms
+
1.____________
Sodium – Na
2.____________
Chloride – Cl+
Potassium – K
3.____________
Calcium – Ca++
4.____________
Hydrogen – H+
5.____________
2-2 Properties of Water
Hydrogen Ions (H+)
The number of
H+ ions
determines
how _______
acidic
a solution will
be.
More H+ = more acidic
2-2 Properties of Water
ATOMS CAN JOIN TOGETHER TO
MOLECULES
MAKE____________
Ex:
Joining 2 HYDROGEN
atoms with 1 OXYGEN atom
WATER molecule.
makes one ______
what kind of
A Chemical Formula tells _________
how many atoms are in a molecule
and __________
H
O
2
EX: ________
2-2 Properties of Water
VERY, VERY LARGE
MOLECULES
MACROMOLECULES
= ____________________
EXAMPLE:
Insulin =
C254 H377 N65 O76 S6
2-2 Properties of Water
MOLECULES CAN BE SHOWN
IN DIFFERENT WAYS
H2O
2-2 Properties of Water
Polar Molecules
Because of the location of
electrons in molecules,
some molecules have an
uneven pattern of
electric charge
+
-
More ___ on one side;
More ___ on the other
EX: water
2-2 Properties of Water
EX: PHOSPHOLIPIDS
The same
molecule can
have both
POLAR and
NON-POLAR
parts
Polar head
NON-polar
tails
2-2 Properties of Water
WHAT HOLDS MOLECULES
TOGETHER?
Molecules are held together by the
attraction between oppositely
charged
________
______________
regions of nearby molecules
van der Waals forces
= _____________________
2-2 Properties of Water
HYDROGEN BONDS
Bonds that form between the
positively charged Hydrogen atom
_________
in one molecule and a
negatively charged atom
__________
in a nearby molecule are called
HYDROGEN BONDS
_____________________
EX: water molecules
are held together
by Hydrogen bonds
Hydrogen bond animation
2-2 Properties of Water
_________
CARBON is the most important
atom found in living things
four
It can join to _______
other atoms at same time
chains
rings or _____
It can form ______
so it can make lots of
different kinds of molecules.
2-2 Properties of Water
ORGANIC
__________
molecules
living things and
are found in
__________
contain CARBON atoms
_____________
2-2 Properties of Water
“Like dissolves like”
HYDROPHILIC
____________________
means “water loving”
POLAR
_________
groups/molecules try to
be near
_________
and touch water or
other polar
______________
molecules
Water makes a great solvent in
living things because so many
molecules found in living things
are polar or have a charge.
2-2 Properties of Water
“Like dissolves like”
HYDROPHOBIC
_________________
means “water fearing”
NON-polar groups/molecules try to
___________
NON-polar molecules
be near other __________
_________
away from
polar
and __________
________
molecules
Oil based paints dissolve
in solvents such as
turpentine
. . . not water.
2-2 Properties of Water
“Like
dissolves
like”
Soap works because it has a
NON-polar end that dissolves grease and
_____________
a __________
Polar end that dissolves in water to
wash away oily dirt.
2-2 Properties of Water
A chemical equation tells what
happens in a chemical reaction
when molecules interact.
→ NaCl + H20
→ _______________
PRODUCTS
NaOH + HCl
REACTANTS
_______________
Molecules that react
Molecules that are
produced
2-2 Properties of Water
REMEMBER:
ALL the chemical reactions
that happen in cells =
METABOLISM
_____________
join
Chemical reactions can _____
molecules together.
break
Chemical reactions can ______
molecules apart.
2-2 Properties of Water
One way to join molecules to make a
bigger molecule is by removing
WATER molecule to make a bond.
a _______
dehydration synthesis
= ____________________
reaction
See an animation
http://nhscience.lonestar.edu/biol/dehydrat/dehydrat.html
2-2 Properties of Water
DEHYDRATION SYNTHESIS
“dehydration”
“synthesis”
water loss
put
parts together
=_____________
_____________
http://io.uwinnipeg.ca/~simmons/macromol/sld003.htm
2-2 Properties of Water
POLYMERIZATION is a
kind of synthesis reaction in which
many small subunits that
are similar join to make
a bigger molecule
These small units are
called ______________
MONOMERS
The big molecule they
make is called a
POLYMER
_____________
2-2 Properties of Water
EXAMPLE:
_________
Nucleotide subunits
(A,T,G,C)
join together
to make
a _____
DNA molecule
2-2 Properties of Water
Chemical reactions can also
break molecules apart.
HYDROLYSIS
______________
= kind of
chemical reaction in which a
molecule is broken apart by adding
WATER
a________
molecule.
hydro = water
“_____”
See an animation
lysis = break apart
“_____”
http://nhscience.lonestar.edu/biol/dehydrat/dehydrat.html
2-2 Properties of Water
opposite of
HYDROLYSIS is the _________
DEHYDRATION SYNTHESIS.
Adding a water molecule breaks the bond.
2-2 Properties of Water
ATP is the energy
molecule used by
all cells.
Breaking a bond
using hydrolysis is
the way ENERGY
is released.
More on this is Chapters 7, 8,& 9
2-2 Properties of Water
Living things use BOTH of these
reactions (and MORE)
kinds of _______
to get the materials they need.
2-2 Properties of Water
WATER is important
for all living things
Average person ~~ 60-70% water
Babies ~~ 78%
Human brain ~~ 90%
2-2 Properties of Water
WHY Water is important to cells:
POLAR
1. It is __________
molecule so it can
____________
DISSOLVE lots of different substances.
absorb lots of ______
HEAT
2. It can _________
WITHOUT changing temperature very much.
(That helps with HOMEOSTASIS)
3. ____________
HYDROGEN BONDS form between water
molecules so they stick together.
REACTANT/PRODUCT
4.Water is an important ___________________
in many CHEMICAL REACTIONS.