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Atoms: The Building
Blocks of Matter
Unit 2

Introduction to the Atom
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Modern Atomic Theory
Subatomic Particles
Isotopes
Ions
Essential Standards and objectives:
1.1.1 Analyze the structure of atoms, isotopes, and ions.
1.1.2 Analyze an atom in terms of the location of electrons.
1.1.3Explain the emission of electromagnetic radiation in spectral form in terms
of the Bohr model.
1.1.4 Explain the process of radioactive decay using nuclear equations and half-life.
2.2.5 Analyze quantitatively the composition of a substance. (Introduction to moles)
Agenda 2/6:
Purpose: To determine the structure of an atom
 Warm-up: Reading on Atoms
 Atomic Theory
 Atomic Structure
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How is it represented?
Isotopes
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How are isotopes represented?
Reading: Cornell notes
Essential questions: What are the characteristics
of an atom?
In your notes: address both individual atoms
and atoms of an element
The Atom: Smallest particle of an
element that retains the chemical
properties of the element.
Essential Questions:
What is an atom?
What is its structure?
What determines properties of an element?
Atoms act in orderly,
predictable ways.
Modern Atomic Theory
2.
All matter:
Atoms of a given element:
3.
Atoms cannot be created nor destroyed in:
4.
In chemical reactions, atoms are
1.
Atomic Theory (cont.)
5.
To form compounds:
Law of Definite Proportions
Law of Multiple Proportions
Summary Table:
Atomic Structure- Subatomic Particles
Subatomic Location Charge Mass Importance
Particle
AMU
AMU = relative measurement and used for comparison
Atomic
Mass Unit
AMU
The “amu” is defined as one twelfth of the mass of an atom of carbon-12 (with
6 protons and 6 neutrons) and has a value of 1.660538921×10−27 kg.
How small is an atom?

http://ed.ted.com/lessons/just-how-small-isan-atom
Designation of Atomic Structure
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Atomic number (Z):
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On the Periodic Table:
Mass number (A):

On the Periodic Table:
Designations for the Atomic
Structure
Atomic number (Z):
20
Ca
40.08
-
On the Periodic Table
Mass number (A):
-
On the Periodic Table
Isotopes
Isotopes Discovery Education Video
Isotopes
(“versions” of the same element)
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Atoms of an element with different masses
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Naturally occurring
Some are stable and some are radioactive
(unstable)
Isotopes of an element have the same number
of ___________ and
a different number of ______________.
Identifying Isotopes

Isotope Notation
1.
2.
On the Periodic Table, the number with the
Decimal point is:
Review: What is Z? What is A?
Determine the number of protons, neutrons, and electrons.
In Nature,
6
C
Carbon
12.011
12
C
Occurs
98.89%
frequency
6
13
C
6
Occurs
1.11 %
frequency
Atoms of the Same Element
Atoms of the Same Element
Atomic Mass

Weighted Average Mass of isotopes
Based on the percentage of each isotope
present.

Mass Abundance
C-12 12.0 x 98.89 =
C-13 13.0 x 1.11=


Grades are often computed using a weighted
average.
Suppose that homework counts 10%, quizzes 20%,
Labs 10% and tests 60%.
 If:
homework grade is 92
quiz grade is 68
lab grade is 88
test grade is 81
What’s the overall grade?

Practice - Worksheet

Atomic Structure
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Identify the number of proton, neutron, &
electrons of an atom of a specific element
Rounding the atomic mass on the Periodic Table
gives the mass of the most common isotope
Atomic Number & Isotopes
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Correct symbol: A & Z
Complete the table
Complete the questions.
Atomic Number & Isotope
Practice: - worksheet
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Find the Average Atomic Mass
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Nucleus of each atom is represented
Graphic below #4 - explains #5-7
Isotopes: Atomic Number & Mass Number
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Determine based on the chart – not the PT
2 Isotope notations
A
 Element – A (X-A)
Z
X
Find Average Atomic Mass
Isotopes: Atomic Number & Mass Number
Element
Isotope
Symbol
Atomic
Number
Z
Mass
Number
A
# of
protons
# of
neutrons
# of
electrons
Review &
Explain:
How does this
graphic demonstrate
the
characteristics of an
atom?
Make sure that you
include each graphic
representation in
your explanation
Atom: Scanning Tunneling
Microscope
.
...............
Development of the Modern Atomic Model
History of Discovering the Atom

http://www.youtube.com/watch?v=thnDxFdk
zZs