ACTIVITIES AND KEYS LESSON 1

PRE-REQUISITES: WHAT DO YOU ALREADY KNOW ABOUT THE TOPIC?

BRAINSTORM ACTIVITY

1. WHAT DID SCIENTISTS KNOW ABOUT THE ATOM BEFORE THE GOLD FOIL EXPERIMENT?

2. WHAT WAS RUTHERFORD’S AIM WHEN HE PLANNED THE GOLD FOIL EXPERIMENT?

1.1  Cloze Test (lesson 1)

Fill in the gaps with the words given below

J. J. Thomson, who____________1 the electron in 1897, proposed the ___________________2model of the atom in 1904 before the discovery of the atomic ___________3in order to include the___________4 in the atomic model. In Thomson's model, the atom is composed of ____________ 5 (which Thomson still called "______________6 ," though G. J. Stoney had proposed that atoms of electricity be called electrons in 1894) surrounded by a ___________7 of positive ____________ 8 to balance the electrons' negative charges, like negatively charged "___________ 9" surrounded by positively charged "_____________ 10” . The electrons (as we know them today) were thought to be _______________ 11 throughout the atom in ____________12 rings. In this model the atom was also sometimes described to have a "__________ 13" of positive charge.

With this model, Thomson abandoned his _________ 14 "nebular atom"_____________ 15, in which the atom was composed of immaterial___________ 16 . Now, at least part of the atom was to be composed of Thomson's particulate negative_______________ 17, although the rest of the __________________ 18 part of the atom remained somewhat nebulous and______________ 19.

The 1904 Thomson model was ________________ 20 by the 1909 _____________ 21 experiment performed by Hans Geiger and Ernest Marsden. This gold foil experiment was _______________ 22 by Ernest Rutherford in 1911 to suggest that there is a very small ____________ 23 of the atom that contains a very high positive ____________ 24 (in the case of gold, enough to _____________ 25 the collective__________  26 charge of about 100 electrons). His ______________ 27 led him to propose the Rutherford model of the atom.


Source: Boundless. “The Thomson Model.” Boundless Physics Boundless, 19 Sep. 2016. Retrieved 26 Mar. 2017 from 
https://www.boundless.com/physics/textbooks/boundless-physics-textbook/atomic-physics-29/the-early-atom-185/the-thomson-model-685-6307/

 

 

electron (s) x2 / plums / rotating / corpuscles x2 / positively charged / gold foil / nucleus  x 2/ negative charge/ conclusions / balance / discovered / earlier / ill-defined / vortices / soup / interpreted / hypothesis / positioned / plum pudding / charge x2/ pudding /cloud / disproved

1.2 COMPREHENSION TEST (lesson 1)

After completing the cloze test, answer the following questions

1.      Who discovered the electron?

2.      Was the atomic nucleus discovered before the plum pudding model presentation?

3.      What was Thomson’s purpose in proposing the plum pudding model?

4.      What were Thomson’s corpuscles?

5.      What is the simile used to describe the balance between positive and negative charge in Thomson’s atom?

6.      Where were the electrons supposed to be positioned?

7.      What was the nebular atom hypothesis about?

8.      What did Thomson realize after abandoning the nebular atom hypothesis?

1. 3 SPEAKING ACTIVITY (lesson 1)


Work in pairs: describe the plum pudding model, explain the most important features

 

 

 

 

 

 

 

 

 

 

 

 

CLOZE TEST LESSON 1 KEY

PRE-REQUISITES: WHAT DO YOU ALREADY KNOW ABOUT THE TOPIC?

BRAINSTORM ACTIVITY (A CURA DELLO STUDENTE)

1.1          Cloze Test (lesson 1 KEY)

Fill in the gaps with the words given below

J. J. Thomson, who discovered the electron in 1897, proposed the plum pudding model of the atom in 1904 before the discovery of the atomic nucleus in order to include the electron in the atomic model. In Thomson's model, the atom is composed of electrons (which Thomson still called "corpuscles," though G. J. Stoney had proposed that atoms of electricity be called electrons in 1894) surrounded by a soup of positive charge to balance the electrons' negative charges, like negatively charged "plums" surrounded by positively charged "pudding” . The electrons (as we know them today) were thought to be positioned throughout the atom in rotating rings. In this model the atom was also sometimes described to have a "cloud" of positive charge.

With this model, Thomson abandoned his earlier "nebular atom" hypothesis, in which the atom was composed of immaterial vortices. Now, at least part of the atom was to be composed of Thomson's particulate negative corpuscles, although the rest of the positively charged part of the atom remained somewhat nebulous and ill-defined.

The 1904 Thomson model was disproved by the 1909 gold foil experiment performed by Hans Geiger and Ernest Marsden. This gold foil experiment was interpreted by Ernest Rutherford in 1911 to suggest that there is a very small nucleus of the atom that contains a very high positive charge (in the case of gold, enough to balance the collective negative charge of about 100 electrons). His conclusions led him to propose the Rutherford model of the atom.



Source: Boundless. “The Thomson Model.” Boundless Physics Boundless, 19 Sep. 2016. Retrieved 26 Mar. 2017 from 
https://www.boundless.com/physics/textbooks/boundless-physics-textbook/atomic-physics-29/the-early-atom-185/the-thomson-model-685-6307/

 

1.2 COMPREHENSION TEST (lesson 1 KEY)

After completing the cloze test, answer the following questions

1.      Who discovered the electron?

 J.J. THOMSON DISCOVERED THE ELECTRON

2.      Was the atomic nucleus discovered before the plum pudding model presentation?

NO, IT WASN’T

3.      What was Thomson’s purpose in proposing the plum pudding model?

HIS AIM WAS TO INCLUDE THE ELECTRON IN THE ATOMIC MODEL

4.      What were Thomson’s corpuscles?

THEY WERE THE ELECTRONS

5.      What is the simile used to describe the balance between positive and negative charge in Thomson’s atom?

LIKE NEGATIVELY CHARGED "PLUMS" SURROUNDED BY POSITIVELY CHARGED "PUDDING”

6.      Where were the electrons supposed to be positioned?

THEY WERE SUPPOSED TO BE POSITIONED THROUGHOUT THE ATOM IN ROTATING RINGS

7.      What was the nebular atom hypothesis about?

IT STATED THAT THE ATOM WAS COMPOSED OF IMMATERIAL VORTICES

8.      What did Thomson realize after abandoning the nebular atom hypothesis?

HE REALIZED THAT, AT LEAST PART OF THE ATOM WAS TO BE COMPOSED OF THOMSON'S PARTICULATE NEGATIVE CORPUSCLES, ALTHOUGH THE REST OF THE POSITIVELY CHARGED PART OF THE ATOM REMAINED SOMEWHAT NEBULOUS AND ILL-DEFINED.

 

 

1.3 SPEAKING ACTIVITY (lesson 1 KEY)

A CURA DELLO STUDENTE