Transcript History of the atoms - Brookwood High School

• The atom
– Picture, parts including charge and location
• Chadwick
– Discovered the…
• Rutherford
– Gold Foil Experiment
• JJ Thomson
– Cathode Ray Tube
• Millikan
– Oil Drop experiment
• Dalton
– Dalton’s Atomic Theory
• Democritus
– His 5 ideas
• Aristotle
– Link with nature (Figure 4-1)
History of Atom
Flip Book
History of the atoms
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5.
Matter is composed of empty space through which
atoms move
Atoms are solid, homogeneous, indestructible,
and indivisible
Different kinds of atoms have different sizes and
shapes
Differing properties are due to the size, shape and
movement of atoms
Changes in matter result from the changes in
groupings of atoms
1. Matter is composed of air, fire, water, and
Earth
His popularity allowed his ideas to persist
into the 1800’s.
Dalton’s Atomic theory
1. All matter is composed of
extremely small particles
called atoms
2. All atoms of a given element
are identical
3. Atoms can not be created,
divided, or destroyed (Law of
Conservation of Mass)
4. Different atoms combine in
simple whole number ratios
to form compounds (Law of
Definite Proportions)
5. In a chemical reaction,
atoms are separated,
combined, or rearranged
Unlike Democritus,
Dalton proved his
ideas with science
experiments.
Subatomic Particles
• JJ Thomson
– Found charge to mass
ratio of electron
– Proved atoms were
divisible into smaller
subatomic particles—Big
Shock to Science
Community
– Cathode Ray Tube
– Would later create the
Plum Pudding Model
Subatomic Particles
• Millikan
– Oil drop experiment
– Found the charge of
one electron
– Electron charge =
1.602x10-19 coulombs
– Accepted as -1 charge
Subatomic Particles
• Ernest Rutherford
– Gold Foil Experiment
• Shoot positive particles at gold foil
Subatomic Particles
Ernest Rutherford
– Gold Foil Experiment
•
Found that most positive
shots went straight through
but some bounced back
1. Atom was largely empty
space through which
electrons moved
2. Atoms contained tiny dense
region called a nucleus that
contained most of the mass
An atom the size of
two football fields
would have a
nucleus the size of
a nickel
Subatomic Particles
• Chadwick
– Discovered the
neutrons
– Neutrons act to
separate the +
protons so that
they don’t
repel each
other
Atom
Smallest particle
of an element
that retains the
properties of the
element