thomson and rutherford’s contributions to the model of the atom

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.

Electrons have a negative chargeThomson believed:

The atom was a positive sphere with electrons embedded in it like raisins in

a plum pudding.

It looks like a

chocolate chip

cookie!!!

Cathode Rays

Cathode rays are beams of tiny, negativelycharged particles called electrons that flow through this tube.

A cathode ray tube is a sealed evacuated glass tube.

J.J Thompson used these tubes to discoverthe 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?

Which of the following properties about cathode rays tell us that they have mass?

The cathode rays are deflected towards the positively charged plate.

The cathode rays drive a smallpropeller located in their path.

Draw Thomson’s atomic model.

What did J.J Thomson use to find the properties of electrons

The cathode ray tube and cathode rays

--

-

-

--

-

--

Positive sphere with electrons embedded in it

RUTHERFORD’S ATOMIC MODEL

HE BELIEVED:

the atom had a central positive nucleus surrounded by negative electrons floating around in a cloud like structure

Ernest Rutherford also developed his own atomic theory

++ +

__

__

_

__

_

_

__++

++

_

Which diagram is Thompson’s and which diagram is Rutherford’s?

Rutherford believed the nucleus was POSITIVE or NEGATIVE?

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 Positive nucleus surrounded by a fuzzy

cloud Electrons not organized

Activities

Worksheet # 6