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Chapter 2
The Chemistry of
Life
Section 2-1: The Nature of Matter
Atom
– Greek “atomos” –
indivisible.
Named by
Democritus
Subatomic
Particle
Charge
The basic unit of Protons Positive 1
all matter
Made up of
Neutrons
Neutral
subatomic
particles:
Electrons
Negative
1
Mass
Where
found
1AMU
“Nucleus”
1 AMU
“Nucleus”
1/1840
Orbitals
Periodic Table of Elements
Table that lists all the names & important
information of elements
• Element – A pure substance consisting of only
1 kind of atom
– Know the elements given to you and their
symbol
Atomic Number = the # of
6
C
Atomic Mass
12
Atomic number
Protons (= the # of
electrons)
Atomic Mass = the # of
Protons + the # of
Neutrons
*All atoms are
electrically neutral
so the # of Protons
must = the # of
Electrons
Figure out the following elements
8
O
16
# Protons
# Electrons
# Neutrons
1
H
1
7
N
14
11
Na
23
17
Cl
35
Bohr Model of the Atom
Has electrons orbiting the nucleus in a
set pattern
–
–
Protons and Neutrons are in the nucleus
Electrons orbit the nucleus in orbitals or
energy levels
•
•
1st orbital gets a max of 2 electrons
2nd and 3rd orbitals gets 8 electrons
Nitrogen
Make Bohr models for the 6 elements below
C
H
O
N
Na
Cl
12
Mg
24
19
K
39
16
S
32
14
Si
28
Isotopes
Elements with the same atomic number
but different atomic masses
(# of neutrons).
6
6
8
8
C
C
O
O
12
14
16
18
Radioactive Isotopes
Are used to follow
chemical pathways
as markers or for
medicinal purposes
in the treatment of
cancer.
Also used as
radioactive tracers
How do elements come together?
Compounds “Compere” to come together - a
substance made up of 2 or more elements in
definite proportions
Ie. H2O, CH4, C6H12O6, NaCl
*The compound will have different chemical
and physical properties from the elements
that it is composed of
ie. NaCl
+
Element
1
Carbon
2
Magnesium
4
Sodium
5
6
12
Number of
Protons
Number of
Electrons
# Electrons
in ourter
most orbital
11
23
17
35
12
N
Chlorine
H
8
S
Iodine
1
16
53
127
53
10
Si
14
11
Ca
20
12
P
13
Iron
14
Aluminum
15
15
31
26
30
Copper
17
Zinc
18
Arsenic
19
25
29
XX
64
XX
35
30
As
K
Fluorine
XX
13
Mn
16
20
Number of
Neutrons
8
12
7
9
Atomic
Mass
O
3
6
Symbol
Atomic
Number
19
19
9
XX
Chemical Bonding
Na11
Cl17
1. Ionic bonds –
transfer electrons between elements
• Since Na has 1 “spare” electron in its
outer energy level and Cl needs 1 more
electron to fill its outer energy level, Na
will transfer 1 electron to Cl’s outer
energy level. This is Ionic bonding
What results is Na+Cl-.
– Na lost 1 electron so it has 1 extra positive
charge – forms a + ion.
– Cl gained an electron so it has 1 extra
negative charge – forms a – ion
• Ions – are charged particles that result
from ionic bonding
Na+Cl-
Try Magnesium and Sulfur
Mg12
S16
Covalent Bonding
H1
O8
Results when atoms share a pair of electrons.
The outer energy level will therefore be
filled for both atoms involved
These are the strongest of bonds needing high
energy to break them or enzymes (to be
discussed later)
In the case of water, both H’s shared electrons
with the oxygen
Do CH4 (Methane)
&
HCl (Hydrogen Chloride)
CH4 Chemical
NH3Formulas
H 2O
Bohr Models
Structural/Molecular Diagrams
Methane
Ammonia
Water
Lewis Electron Dot Configuration
C6
N7
Ne10
F9
H1
B5
Using the model kits, make the following:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
H2O
O2
CH4
HCl
O3
CO2
H2
SiO2
C2H6
C2H4
C2H2
C3H8
NH3
O– Blue – 2
C – Black – 4
N– Red – 3
H – White – 1
Cl – White – 1
Si – Black – 4
Ethane
Ethylene
Acetylene
Propane
Ammonia
Tubes – Covalent Bonds
Draw Structural Diagrams of
Each
Molecule
Smallest unit of a compound.
•
H2O
(1 molecule of water)
•
2H2O
(2 molecules)
•
C6H12O6
(1 molecule of glucose)
•
3C6H12O6
(3 molecules of glucose)
Section 2-2: Water!
65% of you is made up of water!
Hydrogen
+
Hydrogen
Oxygen
Water is a polar molecule
– the Oxygen side of it has a more
negative pull than …
- the Positive pull of Hydrogen
Because of this polarity, when something (like
Na+Cl -) that is bonded ionically is placed in
solution with water, it Dissociates (the ions
separate).
•
The positive ions will be attracted to the
negative side of water (the oxygen side) and
the negative ion will be attracted to the
positive side of water (the hydrogen side).
• This makes water the Universal solvent.
• Therefore, ionic bonds are weak bonds
Dissociation of Salt in Water
Hydrogen Bonding
• Since water is polar, the
Hydrogen side (+) of the
molecule will be attracted to
the negative side of water
(oxygen side).
• This special type of
attraction is called Hbonding
• and is a very weak bond.
Other attractive forces
1. Cohesion –
like molecules being
attracted to each other.
As with water droplets
2. Adhesion
– unlike molecules being attracted to each
other.
As in water being attracted to the glass of a
graduated cylinder forming the meniscus
3. Capillarity
– a combination of the two results in a
liquid being moved through a very thin tube.
Upward force.
Greater in smaller tubes than in larger tubes.
Like using a small straw to pull up a liquid
versus a fat straw.
Mixtures and Solutions
• Mixtures
– composed of 2 or more compounds or
elements that are physically mixed
together.
Your blood cells in plasma.
Salt and pepper together in a shaker
Iron fillings and salt
• Solutions
Solution demonstration
– A mixture made by ionically bonded
compounds dissociating in water
– Solute – compound that is dissolved in a
solution with water.
• Na+ Cl-
– Solvent- The substance in which the
solute is dissolved in.
• Water
• Water may react to form ions (even
though it is bonded covalently) due to
its polarity.
H2O
•
•
H+ + OH-
H+ = Hydrogen ion
OH- = Hydroxide ion
• If the number of
H+ ions in a
solution is = to
the # of OH- ions,
the solution is
neutral
If the H+ ions are >
the OH- ions, then
the solution is an
acid
If the OH- ions are >
the H+ ions, then
the solution is a
base or alkaline.
The pH scale
• is a measurement of the concentration
of H+ ions to OH- ions.
– Each step on the scale represents a 10
fold change.
Acidic
0 1
2
Do pH lab
3
Neutral
4
5
6
7
8
Alkaline
9
10 11 12 13 14
pH
• Scale from 0 – 14
to show how
acidic or alkaline a
solution is
• Logarithmic scale
– (10 fold >/< for
each step)
Activity
1. Using universal pH paper, determine the pH of the following
solutions
2. Dip the tip of the pH paper into the solution, wait a minute and
compare it to the colored scale on the vial
3. List the pH’s of the following solutions:
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
ammonia
vinegar
milk
black coffee
baking soda solution
cola
Milk of Magnesia
lemon juice
Water
Draino
4. On a blank pH scale, place the solutions in the proper spot
pH lab data table
Solution
pH
Amount of H+ or OH from Neutral
a. Ammonia (get
results immediately)
b. Vinegar
c. Milk
d. Black Coffee
e. Baking Soda (stir
well)
f. Cola
g. Milk of Magnesia
(stir well)
h. Lemon Juice
i. Water
j. Soap
k. Draino (get results
immediately)
Ie. For a pH of 8, it
has 10 x OH-
Buffers
– pH of most cells’ fluid is 6.5 – 7. Needs to
maintain homeostasis
To do this, buffers are weak acids
(carbonic acid in blood) or bases that will act
to prevent sharp changes in pH.
Neutralization
– occurs when opposites on the pH scale are
added together to create water and a salt.
Antacids
H+Cl- + Na+OHNa+Cl- + H2O
Reactants
Products
Neutralization lab
Atoms without
Eves
Mendeleev's
Chart
Atoms together
Let's Bond
Water, water
everywhere
What's the
Solution
Democritus called
them atoms
because…
These are pure
substances made
up of only 1 kind
of atom
These are made
up of elements in
a definite
proportion
Where all this
bonding takes
place
Unique property of
water when it
freezes
Subparticles of an
atom
C, H, O, N, Na, Cl,
P, K, S; stand for?
2H2O2 contains
how many
molecules?
Two main types of
chemical bonding
C6H12O6 has how
many atoms of
each element?
Charge of each of
the above
35Cl
17
Its atomic #
& mass in that
order
pH This
How strong are
you?
This is made of 2
or > compounds
physically together
Water's real name
If the
concentration of
H+ and OH- ions is
equal
Unique property of
water that allows it
to be the Unversal
solvent
Type of the above
that salt water
would be
Two types of ions
formed by water
pH of most cells in
human body
Bonding that
transfers electrons
Force that draws
water up a straw
or plant roots
What the salt in
salt water would
be
If an acid, it has
more of this type
of ions
% of water in
humans
Mass of each of
the above
How many protons
and electrons
does the above
have?
Ratio of H:O in
water
Bonding that
shares electrons
Which side of a
water molecules
has a positive pull
What the water in
salt water would
be
If a base, these
ions are found in
greater
concentration
Weak acids or
bases that prevent
sharp changes in
pH
Where to find the
2 subatomic
particles with
mass
# of Neutrons in
the above
Type of change
that occurs when
forming a
compound
Type of bonding
that forms salt
Type of "bond"
formed between H
& O of another
water molecule
What water does
to ionically bonded
compounds in
solution w/ it
Scale which
measures the
concentration of
the ions
When opposite but
equal strength on
the pH scale are
combined
Where the
smallest particles
are found
What if the # was
36 instead of 35?
What's it called
and why?
What happens to
the individual
properties of the
atoms when a
compound is
formed
What Na+ and Clare after bonding
A molecule being
attracted to its
own kind
A mixture of water
and a
nondissolved
material
Stongest pH for an
acid
What is formed
when the above
happens
Charge on any
atom
# of electrons in
each of the
above's orbits
What information
a chemical
formula gives
Molecules being
attracted to
different kinds of
molecules
What would salt
and pepper
together be
considered?
Strongest pH for a
base
If Vinegar has a
pH of 2, how many
more H+ does it
have more than
water?
How water &
methane bond
Atoms
without
Eves
Mendeleev's
Chart
Atoms
together
Let's
Bond
Water,
water
everywhere
What's
the
Solution
pH This
How strong
are you?
unable to be
cut
Elements
Compounds
Between the
electrons
It expands
Mixture
Hydrogen
Hydroxide
Neutral or 7
Protons,
Neutrons and
electrons
Carbon,
Hydrogen,
Oxygen,
Nitrogen,
Sodium,
Chlorine,
Phosphorus,
Potassium &
Sulfur
2
Covalent
and Ionic
It is Polar
Solution
Hydrogen(H+)
& Hydroxide
(OH-)
6 to 7
Positive 1,
neutral and
Negative 1
Atomic # = 17,
Atomic Mass
= 35
6 - Carbon,
12 - Hydrogen
6 Oxygen
Ionic
Capillarity
(capillary
action)
Solute
H+
65%
Protons &
Neutrons are
1, electrons
are 1/1840 or
zero
17
2 to 1
Covalent
Hydrogens'
side
Solvent
OH-
Buffers
Protons and
Neutrons are in
the nucleus
18
Chemical
change
Ionic
Hydrogen
bond
Dissociates
them
pH scale
Neutralization
Electrons orbit
in an electron
cloud
Isotope
New properties
will be formed
different from
original
Ions
Cohesion
Suspension
0
Water and a
salt
Neutral
2, 8, 7
Type and # of
each atom
present
Covalently
(H2O & CH4)
Adhesion
Mixture
14
1 x 106