© copyright pearson prentice hall structure of the nuclear atom > slide 1 of 25 4.2 subatomic...

© Copyright Pearson Prentice Hall

Structure of the Nuclear Atom >

Slide 1 of 25

4.2 Subatomic Particles

Three kinds of subatomic particles are:

___________________________

___________________________

___________________________.

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>Structure of the Nuclear Atom Subatomic Particles

Electrons

In 1897, the English physicist J. J. _____________

(1856–1940) discovered the ____________ which

are ________________ charged _____________

particles.

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Thomson performed experiments that involved

passing __________ ______________ through

gases at low pressure.

The result was a glowing beam, or

_____________ __________, that traveled from

the ___________ to the _______________.

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A cathode ray is deflected by a magnet.

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A cathode ray is deflected by electrically charged plates.

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Cathode Ray Tube

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Thomson concluded that a cathode ray is a

___________ of _____________ which are

parts of the ___________ of all ____________.

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Protons and Neutrons

In 1886, Eugen Goldstein (1850–1930) observed a cathode-ray tube and found rays traveling in the direction opposite to that of the cathode rays. He concluded that they were composed of positive particles.

Such ____________ ________________

subatomic particles are called ____________.

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In 1932, the English physicist James

__________________ (1891–1974) confirmed the

existence of yet another subatomic particle: the

____________.

_____________ are subatomic particles with ___

___________ but with a mass nearly equal to that of a

____________.

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Table 4.1 summarizes the properties of electrons, protons, and neutrons.

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>Structure of the Nuclear Atom The Atomic Nucleus

J.J. Thompson and others supposed the atom was

__________ with __________ charged material and the

______________ were _________ _______________

throughout.

_________ ______

This model of the atom turned out to be short-lived, however,

due to the work of Ernest ____________ (1871–1937).

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Rutherford’s Gold-Foil Experiment

In 1911, Rutherford and his ____________ at the

University of Manchester, ___________, directed a

narrow beam of _________ __________ at a very

thin sheet of __________ foil.

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Rutherford’s Gold-Foil Experiment

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Alpha particles scatter from the gold foil.

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The Rutherford Atomic Model

Rutherford concluded that the atom is mostly _______

___________. All the ________ charge and almost all of

the ________ are ____________ in a small region called

the ____________.

The ___________ is the _________ __________

_____________ of an atom and is composed of

____________ and ________________.

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Structure of the Nuclear Atom >

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The Atomic Nucleus

In the nuclear atom, the ________ and

______________ are located in the

nucleus.

The _____________ are distributed around

the _____________ and occupy almost all

the _______________ of the atom.

4.2

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