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Biological Organization
Biological
Organization
“Biological
Organization”
How living things are
organized
Early Greek Theories of
Matter
• The theory of the 4 Elements
(credited to Empedocles -- 490-435 B.C.)
• According to the Greek theory of matter
everything in the universe is made of four
basic elements:
• Fire
• Air
• Water
• Earth
Empedocles –
Theory of 4 Elements
Democritus 460 B.C. – 370 B.C.

Democritus was a Greek Scientist and
created the 1st atomic theory

He hypothesized that all matter is
composed of tiny units, called atoma.

Considered to be the “father of modern
science”
Atoms
“Atom” in Greek means that which can’t
be cut or divided
 Atoms are the smallest building blocks of
all life

Atoms

Atoms are made of smaller units
called subatomic particles

The three subatomic particles
are:
 Protons (nucleus) +
 Neutrons (nucleus) 0
 Electrons (electron cloud) -
HELIUM
ATOM
Parts
of an
atom
Shell
proton
+
electron
N
N
+
-
neutron
HISTORY OF THE ATOM
John Dalton: 1766 - 1844
Revised the atomic theory to
suggest that all matter was
made up of tiny spheres that
were able to bounce around with
perfect elasticity and called
them
ATOMS
HISTORY OF THE ATOM
Niels Bohr
1885-1962
1913
Bohr further refined the
atomic theory by adding that
the electrons were in orbits.
Rather like planets orbiting
the sun. With each orbit only
able to contain a set number
of electrons.
Elements

Many atoms of the same kind form
elements
Periodic Table

Although there were precursors, the
current periodic table is credited to
Russian chemist Dmitri Mendeleev in
1869.
Periodic Table Podcast

http://www.youtube.com/watch?v=fLSfgNx
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Atomic Number
The periodic table is arranged by atomic
number
 Atomic Number is the number of protons
in the nucleus (same as # of e-)

How can the number of
protons be determined
• Atomic Number
How can the
number of
neutrons be
found?
ATOMIC MASS
The periodic table is
also…
• Organized according to states of
matter
ATOMIC STRUCTURE
Electrons are arranged in Energy Levels or or
Shells around the nucleus of an atom.
•
first shell

a maximum of 2 electrons
•
second shell

a maximum of 8 e-
•
third shell

a maximum of 18 e-
Molecules


2 or more atoms bonded together
Ex. 2 atoms of oxygen make one
oxygen molecule
Compounds


A molecule that contains at least 2
different elements
Ex. 2 hydrogen atoms and one oxygen
atom create one molecule of H20
(water)
How do atoms get “stuck”
together?


Bonds!
To get a stable outer shell of
electrons, atoms either give away,
take on, or share electrons.
3 Types of Bonds



Ionic
Covalent
Metallic
Ionic Bonds



Formed between the transfer of
electrons
Produce charged ions all states.
Conductors and have high melting
point.
Examples; NaCl, CaCl2, K2O
Ions

an atom or molecule with a net
(overall) electric charge due to the
loss or gain of one or more electrons
Covalent Bonds


Formed by the sharing of electrons
Examples; O2, CO2, C2H6, H2O
Metallic Bonds



Bond found in metals, very strong
Good conductors at all states, lustrous,
very high melting points
Examples; Na, Fe, Al, Au, Co
ATOMIC STRUCTURE
The structure and bonds of atoms, molecules and
compounds can be represented by electron dot
diagrams & Lewis Structures
Valence Electrons: The outermost electrons in orbit
that participate in the chemical bonds
Electron dot diagram
show valence electrons of
one element
Make an electron dot diagram for:
-oxygen
-hydrogen
Lewis Structures
show bonding of
molecules
Ex. Water
Subscripts in a chemical formula tell us the
number of atoms of each element
represented
Ex. H₂O
How many atoms of Hydrogen? Oxygen?
Draw a Lewis Structure to represent one
molecule of water.
Lise Meitner
Lise Meitner, (1878 -1968) was an Austrian, physicist who
worked on radioactivity and nuclear physics. Meitner was
part of the team that discovered nuclear fission (splitting an
atom), an achievement for which her colleague Otto
Hahn was awarded the Nobel Prize. Meitner is often
mentioned as one of the most glaring examples of women's
scientific achievement overlooked by the Nobel committee.
1906
1946
Marie Curie
Marie Curie (1867 - 1934) was a chemist,
famous for her pioneering research on
radioactivity. She was the first woman to win a
Nobel Prize
Antoine Lavoisier
(1743 – 1794)

In 1778, Antoine Lavoisier, a French
scientist, conducted many experiments
air and theorized that the gas made some
substances acidic. He named this gas
oxygen, from the Greek words that
loosely translate as "acid maker". While
Lavoisier’s theory about oxygen and
acids proved incorrect, his name stuck.
Lavoisier knew that acids react with some
metals to release another strange and highly
flammable gas called phlogiston. Lavoisier
mixed the two gases, phlogiston and the newly
renamed oxygen, in a closed glass container
and inserted a match. He saw that phlogiston
immediately burned in the presence of oxygen
and afterwards he observed droplets of water
on the glass container.
After careful testing, Lavoisier
realized that the water was formed
by the reaction of phlogiston and
oxygen, and so he renamed
phlogiston hydrogen, from the
Greek words for "water maker".
From these observations, Lavoisier
established the Law of
Conservation of Mass.
Law of Conservation of
Mass


Mass is not lost or gained during a
chemical reaction.
http://www.britannica.com/EBchecked/topicvideo/108987/83548/Antoine-Lavoisier-discovered-the-chemicalexplanation-for-fire
Chemical Equations
Represents chemical changes
A chemical equation is a
symbolic representation of
a chemical reaction.
Equation Example:
The burning of methane gas
in oxygen is:
CH4 + 2 O2 → CO2 + 2 H2O
C=1
H=4
O=4
C=1
H=4
O=4
This is a balanced equation
Reading Chemical
Equations

The two sides of the equation are
separated by an arrow.
– The combination of chemicals before the
reaction are on the left side of the arrow
– The right side indicates the combination
of chemicals after the reaction.
Subscript


Shows the number of atoms of each
element in a molecule
Subscript
H2SO4
– Elements
 Hydrogen; 2 atoms
 Sulfur: 1 atom
 Oxygen: 4 atoms
– 7 atoms total
Coefficients


Represents # of molecules
2H2SO4 – 2 molecules of Sulfuric Acid
– A coefficient is distributed to ALL
elements in a compound
2 – H2 (for a total of 4 H atoms)
 2 – S (for a total of 2 S atoms)
 2 – O4 (for a total of 8 O atoms)

Coefficient
CH4 + 2 O2 → CO2 + 2 H2O
For Example:
Na + O2 → Na2O

In this reaction, sodium (Na) and oxygen
(O2) react to make a single molecule,
Na2O
You can change a
coefficient…..
You can’t change a
subscript
Balancing Equations


The Law of Conservation of Mass
states that in a chemical reaction, the
quantity or amount of each element
does not change.
This means that each side of the
equation must represent the same
quantity of each element; in other
words have the same number of each
kind of atom.
Balancing Equations
Na + O2 → Na2O
In order for this equation to be balanced,
there must be equal amount of Na on
the left hand side and on the right hand
side. Right now, there is 1 Na atom on the
left but 2 Na atoms on the right. We solve
this problem by putting a 2 in front of the
Na on the left hand side, Like this:
2Na + O2 → Na2O
Balancing Equations
2Na + O2 → Na2O
There are 2 Na's on the left and 2 Na's on the
right. But what about the O? We now must
check to see if the O's are balanced on both
sides of the equation. On the left hand side
there are 2 O's and the right hand side only has
one. This is still an unbalanced equation. To fix
this we must put a 2 in front of the Na2O on the
right hand side. Now our equation reads:
2Na + O2 → 2Na2O
Balancing Equations
2Na + O2 → 2Na2O
Notice that the 2 on the right hand side is
"distributed" to both the Na2 and the O.
Currently the left hand side of the equation has
2 Na's and 2O's. The right hand side has 4 Na's
total and 2 O's. Again, this is a problem, there
must be an equal amount of each chemical on
both sides. To fix this let's add 2 more Na's on
the left side. The equation will now look like
this:
4Na + O2 → 2Na2O
Balancing Equations
Tutorial

http://www.youtube.com/watch?v=UG
f60kq_ZDI