Transcript Unique Properties of Water

Atoms, Bonding,
water, and pH
Properties of Matter
• matter is anything that has mass
and takes up space
A. physical properties- can be
measured/observed without
changing the matter
ex. molding clay, folding
paper, melting ice b/c it’s still water
Properties of Matter
B. chemical properties- are only
observed by changing the identity of
matter
ex. burning wood, rust on a car
bumper (things that are very difficult
to reverse)
Phases of Matter
A. solids- state of matter with least
amount of energy, atoms move
about a fixed point.
B. liquids- atoms packed tightly,
have more kinetic E than solids, like
people in a stadium
Phases of Matter
C. gases- very high kinetic E,
atoms are spread out as far as
possible.
D. plasma- extremely high E where
nuclei of atoms are split
Composition of Matter
A. atom- fundamental unit of matter
B. element- substance made of 1
type of atom, can’t be broken
down, represntd by symbol
1. 90 elements are naturally
occurring on Earth
2. 25 are essential to life
3. 96% of human mass is C,
H, O, N
Composition of Matter
C. molecule- 2 or more atoms
chemically combined (no charge)
D. compound- 2 or more
elements chemically combined
(H2O, NaCl)
Atomic Structure
A. neutron- in nucleus of atom (no
charge)
(# of neutrons = atomic mass # atomic #)
B. proton- in the nucleus of atom (+
charge)
(# of protons = atomic #...OR # of
protons = # of electrons)
Atomic Structure
C. electrons- that orbits nucleus in
orbitals, shells, or energy levels (charge)
(# of electrons = atomic #...OR
# of electrons = # of protons)
Atomic Structure
• Why are atoms neutral??
• # of protons = # of electrons
(charges balance out)
Atomic Structure
D. energy levels- where electrons
are located, higher levels are
farthest from the nucleus, last
energy level has the electrons
associated with bonding (inner ones
aren’t involved)
Atomic Structure
E. atomic number- (whole #)
number of protons in an atom
F. atomic mass (mass number)(decimal #) # of protons + # of
neutrons, mass of nucleus
Atomic Structure
G. isotopes- atoms of the same
element with different # of neutrons,
some radioactive
(milk analogy: whole milk, 2%, 1%,
1/2%, skim---all milk but different)
Atomic Structure
H. radioactive isotopes- elements
with unstable nuclei, emit dangerous
radiation as they undergo the
process to become stable
1. uses- diagnose and treat
diseases
2. phosphorus 32 tracer
(chem. rxns are followed in the
body)
Atomic Structure
3. iodine 131- studies of the thyroid
as it absorbs iodine
4. carbon 14- treats brain tumors
5. cobalt 60- used in cancer
treatments
Chemical Bonding
(chemical joining of atoms)
A. ionic- transfer of electrons from
1 atom to another, produces ions or
charged particles (like NaCl)
1. cations are positively
charged
2. anions are negatively
charged
Chemical Bonding
B. covalent- sharing of electrons
between 2 atoms
**can be single, double, or
triple depends on the number of
electrons being shared.
Chemical Bonding
• EX. water, H2O has 2 single
bonds
Water
A. is a polar covalent molecule
B. polarity makes it a good solvent
(universal solvent), it dissolves
substances to form:
Water
1. mixtures-2 or more
elements/compounds evenly
distributed but not chemically
combined, they can be separated
without chemicals.
homo=same * homogeneousmixture that doesn’t show identity of
its compounds
Water
• hetero=other/different *
heterogeneous- mixture that
shows identity of its compds
a. solutions- uniformly
dissolved, usually see through
(homogenous)
b. suspensions- large clumps
of molecules floating/suspended in a
liquid
Water
(our blood, milk, Amoxil suspension,
italian dressing)
* solute- substance being
dissolved, sugar or Kool-Aid
* solvent- substance doing the
dissolving, water
Unique Properties of
Water
A. *cohesion* gives water high
surface tension (water has a
“skin”)~ bugs can walk on it
Unique Properties of
Water
B. adhesion causes *capillary
action* (creeps up thin tubes)~
plants
Unique Properties of
Water
C. expands/is less dense when it
*freezes* (it floats)~ lakes/ponds,
frost action makes soil
D. high heat of *vaporization*
(evaporates slowly)~ helps
organisms keep water, maintains
stable climate
Unique Properties of
Water
• E. high specific heat so it *resists
temperature change* ~ stable
environment for org., regulate
body temp
Hydrogen Bonding
A. attraction of
opposite
charges
between H and
O of different
water molecules
B. weak bonds
because they
are simply an
attraction
Hydrogen Bonding
C. help hold large molecules
together (organic compounds like
protein and DNA)
D. gives water its unique properties,
including cohesion and adhesion!!
Chemical Reactions
A. Parts of a reaction
1. reactants- chemicals mixed
in a rxn
2. products- new chemicals
formed in a rxn
B. when ionic compounds dissolve
in water the ions dissociate
NaCl + H2O  (Na+) + (Cl-) + H2O
Chemical Reactions
C. when certain ionic compound
dissolve in water, they form acids
and bases
*All of the chemical reactions in an
organism (metabolism) depend on
the pH of the environment
Acids
(hydrogen ions and hydronium ions
are the same thing)
A. form hydrogen ions (H+) in water
HCl + H2O  (H+) + (Cl-) + H2O
B. have pH (potential hydrogen)
below 7
C. tend to taste sour
Bases
A. form hydroxide ions (OH-) in
water
NaOH+ H2O(Na+) + (OH-) + H2O
B. have pH above 7
C. taste bitter and feel slippery
pH
A. mathematical scale used to
determine the concentration of H+ to
OH- ions
B. scale range is from 1 to 14
pH
C. 1 2 3 4 5 6
7
8 9 10 11 12 13 14
strong
neutral
strong
acids
solution
bases
D. indicators change color in the
presence of an acid or base (like red
cabbage)
pH