Alchemy Unit
Investigation IV:
Subatomic World
Lesson 1: Island of Stability
Lesson 2: It’s Greek to Me
Lesson 3: ELEMENTary Education
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Alchemy Unit – Investigation IV
Lesson 1:
Island of Stability
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ChemCatalyst
The isotope notation for an atom of
copper and an atom of gold are given
below.
63
197
Cu
29
79
Au
• How could you change a copper atom
into a gold atom?
• What would you need to change? Give
specific numbers.
• Why is this change called a nuclear
reaction?
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
The Big Question
• What is the range of the number of
neutrons found in isotopes of various
elements?
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
You will be able to:
• Determine how many neutrons are
required to make a stable element with
a given number of protons.
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
Notes
• Nuclear chemistry is the study of the
nucleus of the atom.
• The band of stability is the range in
the number of neutrons for a given
number of protons for isotopes that are
found in nature.
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
Activity
Purpose: Some combinations of
neutrons, electrons, and protons are not
stable enough to be called elements.
This lesson shows you how to predict
the numbers of neutrons, electrons, and
protons of the isotopes they are likely to
find in nature.
(cont.)
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
(cont.)
(cont.)
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
Making Sense
• What kind of generalization can you
make about how the number of
protons and neutrons are related to
each other in the elements?
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
Notes
• Radioactive elements are less stable
because the isotope is lost over time
as pieces of the nucleus
spontaneously emerge.
• The concept of isotope stability is
highly dependent on time. Atoms that
exist for a long time are referred to as
stable. Radioactive atoms disappear
over time and are referred to as
(cont.)
unstable.
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
(cont.)
• Any isotope that is around long enough
to be detected and measured qualifies
as an element, but still can be highly
unstable and radioactive.
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
Check-In
• Use your graph to determine how
many neutrons you would need to
make a stable element with 75
protons.
• How many neutrons would make a
radioactive element with 75 protons?
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
Wrap-Up
• In order for an atom to be considered an
element, it has to have a stable nucleus
and exist long enough to be detected.
• The neutron to proton ratio is an important
factor in determining the stability of a
nucleus.
• Some isotopes are more stable than
others. Unstable isotopes undergo nuclear
decay to produce atoms with lower mass.
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
Alchemy Unit – Investigation IV
Lesson 2:
It’s Greek to Me
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ChemCatalyst
Uranium-238 is used in nuclear reactors to
generate electricity. In the nuclear reactor,
uranium-238 changes to lead-209.
238
92
U
209
82
Pb
• How can atoms of uranium-238 change
into atoms of lead-209?
• The nuclear reaction is initiated by
colliding the uranium-238 with 01 n . What
do you think this symbol represents?
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
The Big Question
• What changes in the nucleus during
radioactive decay?
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
You will be able to:
• Predict the result of radioactive decay
of an atom.
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
Notes
• A nuclear reaction happens when the
nucleus of an atom is unstable and
spontaneously decays emitting
particles.
• There are two types of nuclear decay,
alpha and beta. Depending on the
type of decay either an alpha particle
or beta particle is emitted.
(cont.)
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
(cont.)
• Chemists use equations like the
following one to represent nuclear
reactions.
47
Ca
20
238
U
92
g
g
 +
47
Sc
21
 +
234
Th
90
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
Activity
Purpose: This activity introduces you to
two common forms of nuclear decay.
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
Making Sense
• Give a specific example of how a chemist
might make gold using alpha decay. Be
specific about which isotope of gold is made.
• Give a specific example of how a chemist
might make gold using beta decay. Be
specific about which isotope of gold is made.
• Would the isotopes of gold prepared by
alpha and beta decay be located in the band
of stability?
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
Notes
• Alpha decay and beta decay are two
forms of radiation or nuclear decay.
• During alpha decay a nucleus is
splitting into two smaller elements, one
of which is always a helium atom.
• Chemists use the symbol (the Greek
letter alpha) to represent an alpha
particle.
(cont.)
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
(cont.)
• During beta decay a neutron inside the
nucleus of an atom emits an electron. This
electron is a part of nuclear decay and
therefore comes from the nucleus.
• Under certain circumstances each neutron
can be further split up into an electron and
a proton.
• Removal of an electron from a neutron
alters the neutron so that it becomes a
(cont.)
proton.
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
(cont.)
• The process of splitting a large nucleus
into smaller ones is called nuclear
fission.
• Besides alpha and beta particles,
many radioactive nuclei release energy
in the form of gamma rays
( rays).
(cont.)
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
(cont.)
• The release of a gamma ray causes no
change to either the mass number or
the atomic number of an atom because
a gamma ray has no mass.
• Gamma radiation by itself does not
change the identity of the atom.
However, gamma ray emission usually
occurs whenever there is alpha or beta
emission.
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
Check-In
• What products do you expect if an
atom of actinium-227 undergoes alpha
decay?
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
Wrap-Up
• When changes occur in the nucleus of
an atom it is called a nuclear reaction.
• When an alpha particle is emitted from
an atom, the nucleus loses two protons
and two neutrons. An alpha particle is
the same as a helium atom.
• When a beta particle is emitted from
an atom, the nucleus gains a proton
and loses a neutron. A beta particle is
the same as an electron.
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
Alchemy Unit – Investigation IV
Lesson 3:
ELEMENTary Education
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ChemCatalyst
The periodic table lists every element
after uranium, U, as “human-made”
elements.
• How are elements made in nature and
by scientists?
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
The Big Question
• How are elements formed?
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
You will be able to:
• Explain what it would take to turn one
element into another.
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
Activity
Purpose: The goal of this lesson is to
examine the formation of the elements.
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
Making Sense
• Why are the small owls breaking out
their digging tools at the end of the
comic strip?
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
Notes
• The process of element formation is called
nucleosynthesis.
• Nuclear fusion is a process that produces
bigger elements from smaller ones. It
requires extraordinarily high temperatures.
At such high temperatures, nuclei are
moving so fast that collisions between
them can overcome the natural repulsion
of their positive charges.
(cont.)
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
(cont.)
• Heavier elements do not burst into fiery
fusion by combination with -particles.
They are formed by neutron capture
followed by beta decay, among other
processes. Nuclei add neutrons until one
is converted into a proton and an electron
(beta decay). A new element is formed
because the atomic number increases by
one. This happens in supernova
explosions.
(cont.)
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
(cont.)
• Chemical reactions are ones in which
atoms remain unchanged.
• Revised definition of an element: Stable
elements cannot be broken apart into new
elements in chemical reactions. It is possible
to convert one element into another in
nuclear reactions, but this requires a lot of
energy for stable elements. Unstable
elements undergo radioactive decay, and
are broken apart spontaneously.
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
Check-In
Consider the chemical reaction between
hydrogen and oxygen to form water.
H2 + 2O2

2H2O
• Name two ways in which a chemical
reaction is different from a nuclear
reaction.
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV
Wrap-Up
• Elements are converted from one to
another in nuclear reactions, but not in
chemical reactions.
• Nuclear reactions involve the energy of
a supernova.
© 2004 Key Curriculum Press.
Unit 1 • Investigation IV