Theory of the Atom
Theory:
Explanation based
on repeated tests
and observations
Philosophy:
Study what makes the universe
work by using examples and
the human mind
Science:
Study what makes the universe
work by observation,
experiment and physical proof
Once Upon A Time
440 BC - Democritus
“atomos” = indivisible
* He also believed that
the moon and stars
were planets far away
from us.
p. 80 in
text
350 BC Aristotle
• Philosopher
• Tutor to Alexander the Great
Everything
comes from
the 4
elements
p. 81 in
text
Meanwhile…..
Alchemists- tried mixing different
materials together to make new
things
medicine
Acids for dissolving things
Cleaning chemicals
Love potions
Magic spells
Meanwhile…..
Some alchemists believe in a
“Philosopher’s Stone”
Transmute – change one
material into another
Because of the fakers, alchemy
became illegal almost
everywhere, so they had to “go
underground”
Meanwhile…..
Alchemists- by doing experiments
in which they broke complicated
chemicals into simpler ones,
discovered different “pure”
substances.
Pure means these substances are not
mixed with something else – ex wood
is made of other things and will break
down, but Gold cannot be broken into
anything simpler.
Meanwhile…..
These pure substances
become known as
“elements”. Alchemists
realize that there are
actually many elements not
just four.
Meanwhile…..
Different materials are
made by mixing
together these
elements in certain
proportions:
Water is H20. It is ALWAYS 2
Hydrogen and 1 Oxygen
hooked together.
1803 John Dalton
England – Quaker school
teacher
Each element is a different kind
of “building blocks”
atoms
p. 81 in
text
1803 John Dalton
The atoms
combine in certain
ratios to make
new things
p. 81 in
text
1803 John Dalton
Atoms are like little
billiard balls
that stick together or
bounce off each
other.
p. 81 in
text
•Atoms are the smallest particles
and cannot be broken into smaller
units
•Atoms of the same element are
the same. Different elements=
different kinds of atoms
•Atoms join in certain proportions to
make new substances.
p. 81 in
text
1897 J J Thomson England
Experimented with the cathode ray
tube
1897 J J Thomson England
•Experimented with the
cathode ray tube
•Decided atoms actually
have TWO parts
mostly positive with little
negative chunks
1897 J J Thomson England
•His model for explaining the atom
became known as
1909 Ernie Rutherford
from New Zealand
•Student of Thomson
•Experiments with new-fangled
discovery “radiation”
•Decides to shoot radiation at
Thomson’s pudding
1909 Ernie Rutherford
Radioactive
material
Why
Gold?
If the atom is like pudding,
the beam should punch right
through
1909 Ernie Rutherford
It turned out some of the
particles bounced off
something
1909 Ernie Rutherford
Ernie decided the atom was
mostly empty space with the
positive part in the center and
the negative particles orbiting
This is the
Solar System
Model
1913 Niels Bohr -Denmark
•Agreed there are
+ and – particles
•Proves that – particles actually
change paths according to the
amount of energy they have
•Paths have different shapes,
not circles
1913 Niels Bohr -Denmark
•Spectrophotometer measure
light waves
•He used the wavelengths of
light generated by heated
objects as his tool
•This is called spectral analysis
1913 Niels Bohr
Niels Bohr model
Energy Level
model
Modern Theory
Erwin SchrÖdinger
Werner Heisenberg
- particles are so tiny and
moving so quickly, we can’t
actually predict exactly where
they are, only where they are
most likely to be.
Modern Theory
Erwin SchrÖdinger
Werner Heisenberg
Parts of an atom
Positive
particles in
the center
Negative
particles orbit
the center
PROTONS
ELECTRONS
WHAT HOLDS THEM
TOGETHER????
1932 James Chadwick
England
We can explain
that the negative
particles stay in
orbit because
opposites attract
1932 James Chadwick
England
What keeps the
positive
particles in the
center from
flying apart?
Parts of an atom
Chadwick used the
masses of the atoms
to prove there are
actually neutral
particles between the
positive particles
Parts of an atom
protons
nucleus
neutrons
electrons
This is what you need to know to learn chemistry
The Atom Song
In the 1960’s scientists developed a new
technology – “Atom Smashers” which could
accelerate protons to high speeds then smash
them together. Scientists discovered that the
collisions would result little particles flying off
in every direction (see p.78 in your book for an
interesting picture!)
In 1964, Murray Gell-Mann and George Zweig
suggested that these little particles could be
explained as combinations of just three
fundamental particles. Gell-Mann chose the
name "quarks," pronounced "kworks," for these
three particles, a nonsense word used by James
Joyce in the novel Finnegan's Wake:
"Three quarks for Muster Mark!"
This is what you need to know to learn nuclear
physics
Quarks
http://science.howstuffworks.com/atom-smasher11.htm
If you are REALLY interested, check out this link!
http://io9.com/5639192/the-ultimate-field-guide-to-subatomic-particles
Parts of an atom
Quarks
protons
neutrons
electrons
up
down
charm
strange
top
bottom
leptons
http://www.particleadventure.org/index.html
http://science.howstuffworks.com/atom-smasher11.htm
String Theory
String theory uses a model of onedimensional strings in place of the
particles of quantum physics.
These strings, the size of the Planck
length (i.e. 10-35 m) vibrate at
specific resonant frequencies
(kinda like plucking a guitar string).
http://www.superstringtheory.com/basics/index.html
String Theory
There are two basic types of
string theories: those with
closed string loops that can
break into open strings and
those with closed string
loops that can't break into
open strings.
String Theory
The basic building blocks of
matter, quarks and electrons,
are really one dimensional
vibrating strings that are
embedded within an 11
dimensional space
How do I find information about an atom?
Use the Periodic Table
Atomic mass
Atomic number
Chemical symbol
Element Name
Number of protons in
Atomic mass
an atom
Atomic number
TOTAL number of
particles in the
nucleus
Chemical
symbol
Abbreviation for the
element name –may
useElement
the LATIN
name
Name
Check these out!!!!
http://particleadventure.org
http://www.nuclecu.unam.mx/~alberto/physi
cs/string.html
http://www.fnal.gov/pub/inquiring/matter/ma
deof/index.html
http://www.chem4kids.com