Chapter 5
Atomic Theory:
The Nuclear Model
of the 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.
Section 5.1
Dalton’s 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.
Goal 1
Identify the main features of Dalton’s 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.
Precursors to John Dalton’s atomic theory
Law of Definite Composition
The percentage by mass of the elements
in a compound is always the same
Law of Conservation of Mass
In a chemical change, mass is converved
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Dalton’s 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 compounds
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.
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.
Goal 2
Identify the three major subatomic particles by
charge and approximate atomic mass,
expressed in atomic mass units.
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 parts
known as subatomic particles.
Electron
1– charge, 0.000549 amu
Proton
1+ charge, 1.00728 amu
Neutron
no 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.
Goal 3
Describe and/or interpret the Rutherford
scattering experiment and the nuclear model
of the 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.
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 extremely
small, 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 space
that 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.
The diameter of an atom is
approximately 100,000
times the diameter 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.
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.
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.
Goal 4
Explain what isotopes of an element are and
how they differ from each other.
Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright © 2007 Brooks/Cole, a part of the Thomson Corporation.
Goal 5
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.
Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright © 2007 Brooks/Cole, a part of the Thomson Corporation.
Goal 6
Identify the features of Dalton’s atomic theory
that are no longer considered valid, and
explain why.
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 element
has the same number of protons.
The number of protons in an atom of an
element 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 identical
Some 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
masses—different numbers of neutrons—
are 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.
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 name–Mass 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
mass number
atomic number
A
Z
Sy
Sy
Sy
Example:
What are the nuclear symbols for
carbon-12 and carbon-13?
12
6
C
13
6
C
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 5.5
Atomic Mass
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Goal 7
Define and use the atomic mass unit (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.
Goal 8
Given the relative abundances of the natural
isotopes of an element and the atomic mass
of each isotope, calculate the atomic mass of
the element.
Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright © 2007 Brooks/Cole, a part of the Thomson Corporation.
Masses of atoms are expressed in
atomic mass units, amu
1
1 amu
12 amu
12
the mass of one carbon atom
the mass of one carbon atom
C atom: 6 p+, 6 n, 6 e–
Since the mass of a p+ and a n are about the
same, and since the mass of an e– is about 0,
12 amu = mass of (6 + 6) (p+ + n)
12 amu = mass of 12 nuclear subatomic particles
1 amu = mass of 1 nuclear subatomic particle
Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright © 2007 Brooks/Cole, a part of the Thomson Corporation.
1 amu = 1.66 x 10–24 g
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Mass Spectrum of Neon
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Atomic Mass
(of an element):
The average mass of all atoms of an
element as they occur in nature.
Chlorine has two natural isotopes:
75.78% is chlorine-35 at 34.968852721 amu
24.22% is chlorine-37 at 36.96590262 amu
What is the atomic mass of chlorine?
0.7578 x 34.968852721 amu =
0.2422 x 36.96590262 amu =
26.50 amu
8.953 amu
35.45 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.
Section 5.6
The Periodic Table
Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright © 2007 Brooks/Cole, a part of the Thomson Corporation.
Goal 9
Distinguish between groups and periods in
the periodic table and identify them by
number.
Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright © 2007 Brooks/Cole, a part of the Thomson Corporation.
Goal 10
Given the atomic number of an element, use
a periodic table to find the symbol and atomic
mass of that element, and identify the period
and group in which it is found.
Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright © 2007 Brooks/Cole, a part of the Thomson Corporation.
When elements are arranged according
to their atomic masses, certain properties
repeat at periodic intervals
(Mendeleev and Meyer, 1869)
Periodic Table
of the Elements
A table that arranges the elements in
order of atomic number with elements
with similar properties in the same column
Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright © 2007 Brooks/Cole, a part of the Thomson Corporation.
Mendeleev had blank spaces in his periodic table.
He averaged the properties of the surrounding
elements to predict properties of as-yet
undiscovered elements.
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.
Periods
Horizontal rows in the periodic table
Numbered 1–7, top to bottom
(numbers usually not printed)
Groups (or Chemical Families)
Vertical columns in the periodic table
U.S. numbering: A groups and B groups
IUPAC numbering: 1-18, left to right
Presentation Slides to Accompany Cracolice/Peters Introductory Chemistry: An Active Learning Approach, Third Edition Copyright © 2007 Brooks/Cole, a part of the Thomson Corporation.
Main group elements
Elements in the U.S. A-groups
Transition elements
Elements in the U.S. B-groups
Metals
Elements on the left of the stair-step line
Nonmetals
Elements on the right of the stair-step line
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 5.7
Elemental Symbols and
the Periodic Table
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Goal 11
Given the name or the symbol of an element
in Figure 5.9, write the other.
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.
aluminum
argon
barium
beryllium
boron
Al
Ar
Ba
Be
B
Br
Ca
C
Cl
Cr
bromine
calcium
carbon
chlorine
chromium
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cobalt
copper
fluorine
helium
hydrogen
Co
Cu
F
He
H
I
Fe
Kr
Pb
Li
iodine
iron
krypton
lead
lithium
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magnesium
manganese
mercury
neon
nickel
Mg
Mn
Hg
Ne
Ni
N
O
P
K
Si
nitrogen
oxygen
phosphorus
potassium
silicon
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silver
sodium
sulfur
tin
zinc
Ag
Na
S
Sn
Zn
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