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1

Atomic Theory:

The Nuclear Modelof the Atom

Chapter 5

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

Section 5.1

Daltons Atomic Theory

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

Identify the main features of Daltons atomic

theory.

Goal 1

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

Precursors to John Daltons atomic theory

Law of Definite Composition

The percentage by mass of the elementsin a compound is always the same

Law of Conservation of Mass

In a chemical change, mass is converved

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

Daltons Atomic Theory (1808)

Each element is made up of tiny,individual particles called atoms.

Atoms are indivisible;

they cannot be created or destroyed

All atoms of each element

are identical in every respect.

Atoms of one element are different

from atoms of any other element.

Atoms of one element may combine with atoms of other

elements, usually in the ratio of small, whole numbers,

to form chemical compoundsPresentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

2

Law of Multiple Proportions

When two elements combine to form more than one

compound, the different weights of one element that

combine with the same weight of the other element are in a simple ratio of whole numbers.

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

Section 5.2

Subatomic Particles

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

Identify the three major subatomic particles by

charge and approximate atomic mass, expressed

in atomic mass units.

Goal 2

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

An atom contains smaller partsknown as subatomic particles.

Electron

1 charge, 0.000549 amu

Proton

1+ charge, 1.00728 amu

Neutronno charge, 1.00867 amu

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

Section 5.3

The Nuclear Atom

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

3

Describe and/or interpret the Rutherford

scattering experiment and the nuclear model of

the atom.

Goal 3

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

The Nuclear Model of the Atom

Every atom contains an extremelysmall, extremely dense nucleus.

All of the positive charge and nearly all of the mass of

an atom are concentrated in the nucleus.

The nucleus is surrounded by a much

larger volume of nearly empty spacethat makes up the rest of the atom.

The space outside the nucleus is very thinly populated by electrons, the total charge of which exactly balances

the positive charge of the nucleus.Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

The diameter of an atom is approximately 100,000

times the diameter of the

nucleus.

If the nucleus was the size of a pea,

there would be a 1 km distance

from it to its nearest neighbor

1 km

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

4

Section 5.4

Isotopes

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

Explain what isotopes of an element are and how

they differ from each other.

Goal 4

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

For an isotope of any element whose chemical

symbol is known, given one of the following, state

the other two: (a) nuclear symbol, (b) number of

protons and neutrons, (c) atomic number and mass number.

Goal 5

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

Identify the features of Daltons atomic theory

that are no longer considered valid, and explain

why.

Goal 6

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

Every atom of a particular elementhas the same number of protons.

The number of protons in an atom of anelement is the atomic number, Z

Atoms are electrically neutral

Protons have a 1+ charge

Electrons have a 1 charge

The number of electrons in an atom therefore

must be equal to the number of protons

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

All atoms of an element are not identicalSome have more mass than others

Since the number of protons and electrons

in an atom of an element are fixed,there must be variation in the number

of neutrons that causes this difference in mass

Atoms of the same element that have different

massesdifferent numbers of neutronsare called isotopes

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

5

An isotope is identified by its mass number, A

Mass number = A =

Total number of protons + neutrons

Mass number = # of protons + # of neutrons

A = Z + # of neutrons

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

Name of an Isotope

Elemental nameMass number

Example:

A carbon atom with 6 protons and 6 neutrons

Mass number: 6 + 6 = 12

Name: carbon-12

What is the name of the carbon

isotope with 7 neutrons?

carbon-13

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a part of the Thomson Corporation.

Symbol of an Isotope

Known as a nuclear symbol

# of protons + # of neutrons

# of protons Sy

mass number

atomic numberSy

A

Z Sy

Example:

What are the nuclear symbols for

carbon-12 and carbon-13?

12

6C

13

6C

Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright 2007

Brooks/Cole, a

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