Transcript File

Thomson and Rutherford’s
contributions to the model of
the atom
J.J. Thomson’s Atomic Model
Thomson discovered the electron while
experimenting with cathode rays.
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Electrons have a
negative charge
Thomson believed:
The atom was a positive sphere with
electrons embedded in it like raisins in a
plum pudding.
Cathode Rays
A cathode ray tube is
a sealed evacuated
glass tube.
Cathode rays are beams of tiny, negatively
charged particles called electrons that
flow through this tube.
J.J Thompson used these tubes to discover
the various properties of cathode rays
(electrons)
Properties Of Cathode Rays
1. The cathode rays travel in
a straight line.
2. The cathode rays drive a small
propeller located in their path.
This tells us that cathode rays have
mass.
Properties Of Cathode Rays
3. The cathode rays cause the
shadow of the object in their
path to be projected on a
fluorescent screen.
Properties Of Cathode Rays
4. The cathode rays are attracted
towards the positively charged
plate.
This tells us that cathode rays are
negative.
Which of the following properties about
cathode rays tell us that they are in fact
negative?
The cathode rays are deflected
towards the positively charged
plate.
Which of the following properties about
cathode rays tell us that they have mass?
The cathode rays drive a small
propeller located in their path.
Draw Thomson’s atomic model.
- - - - - Positive sphere with electrons embedded in it
What did J.J Thomson use to find the
properties of electrons
The cathode ray tube and cathode
rays
RUTHERFORD’S ATOMIC MODEL
Ernest Rutherford also developed
his own atomic theory
HE BELIEVED:
the atom had a central positive nucleus
surrounded by negative electrons floating
around in a cloud like structure
Which diagram is Thompson’s and which
diagram is Rutherford’s?
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Rutherford believed the nucleus was
POSITIVE or NEGATIVE?
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Thomson’s Model is known as the
plum pudding model. He also
discovered the electron.
Memorize the four properties of
cathode rays
Rutherford’s Model
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Positive nucleus surrounded by a fuzzy
cloud
Electrons not organized