Download ATOMIC THEORY Philosophical Idea to Scientific Theory

ATOMIC THEORY
Philosophical Idea to Scientific Theory
Chapter 3
Section 1
DEMOCRITUS
A Greek
philosopher
Believed that
atoms were the
smallest particles
of matter and that
different atoms
comprised different
materials.
400 B.C.
Atom is from the
Greek word atomos,
meaning, indivisible.
Purely philosophical
ideas at this point.
ARISTOTLE
(300 B.C.)
Greek philosopher who
rejected Democritus’ atom.
Proposed that matter was
continuous.
Called contiuous matter,
hyle.
ISAAC NEWTON
and ROBERT BOYLE
1600
Rejected
Aristotle’s
hyle theory in
published
articles.
Still did not have proof
that atoms existed.
LAVOISIER
1700’s
The “Father of
Chemistry”
One of the first
scientists to use
numeric data to
support his
hypothesis.
Proposed the
Law of Conservation of Mass in 1782.
Law of Conservation of Mass
Matter cannot be created or
destroyed during a chemical
reaction.
Mass of reactants = mass
of products.
JOSEPH PROUST
late 1700’s
Observed that specific
substances (compounds) always
contain the same elements in the
same ratio by mass.
This is known as the
Law of Definite Proportions.
Ex. NaCl always consists of 60.66
% chlorine and 39.43 % sodium
CLAUDE – LOUIS BERTHOLLET
and JOHN DALTON
1790’s
Law of Multiple Proportions
When multiple compounds of
the same 2 elements exist, the
masses of the second element
combined with a certain mass
of the first is always a ratio of
small whole numbers.
MULTIPLE PROPORTIONS
 Example:
Mass of
Oxygen
Mass of Ratio of O/N
Nitrogen
NO
16.00 g
14.01 g
16.00/14.01= 1.14
NO2
32.00 g
14.01 g
32.00/14.01 =2.28
2.28 / 1.14 = 2/1
JOHN DALTON
1800’s
Proposed his Atomic Theory in
1808 based on the following:
• Democritus’ atom
• Law of
conservation of
mass
• Law of definite
proportions
• Law of multiple
proportions
5 Principles of
Dalton’s Atomic Theory
1. All matter is composed of
extremely small particles
called atoms which cannot
be subdivided, created or
destroyed.
5 Principles of
Dalton’s Atomic Theory
2. Atoms of a given element are
identical in their physical and
chemical properties.
3. Atoms of different elements
differ in their physical and
chemical properties.
5 Principles of
Dalton’s Atomic Theory
4. Atoms of different
elements combine in
simple, whole number
ratios to form compounds.
5 Principles of
Dalton’s Atomic Theory
5. In chemical reactions,
atoms are combined,
separated, or rearranged,
but never created destroyed
or changed.
CURRENT ATOMIC THEORY
The first principle of Dalton’s atomic
theory has been refuted.
Atoms can be created and destroyed.
Atoms can be subdivided into
subatomic particles:
Proton
Neutron
Electron
How were each of these discovered?
INTERNET RESEARCH
Use the internet to complete the next few
pages of your note guide. Name the
experiment, read the procedures and
determine the major conclusions of each.
SCIENTISTS of INTEREST:
JJ Thomson, Robert Millikan, and Earnest
Rutherford
EXPERIMENTS:
Cathode Ray Tube, Oil Drop, and the Gold
Foil Experiment.
ADDITIONAL SUBATOMIC
PARTICLES
Who discovered the neutron?
What is a quark? Find the names and
characteristics of the quarks.