Lesson 2:
It’s Greek to Me
ChemCatalyst
Uranium-238 is used in nuclear reactors
to generate electricity. In the nuclear
reactor, uranium-238 changes to lead209.
• How can atoms of uranium-238
change into atoms of lead-209?
• The nuclear reaction is initiated by
1
colliding the uranium-238 with 0 n .
What do you think this symbol
represents?
The Big Question
• What changes in the nucleus during
radioactive decay?
• Goal - Predict the result of radioactive
decay of an atom.
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.
• 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
A more detailed map
Activity
Purpose: This activity introduces you to
two common forms of nuclear decay.
It’s Greek to me…
Parent
isotope
Particle
emitted
Daughter Change
isotope
in atomic
#
# of
protons
lost or
gained
# of
neutrons
lost or
gained
Change
in mass
number
Alpha or
beta
decay?
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?
Notes
• Alpha (α) decay and beta (β)decay are two
forms of 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 α (Greek letter) to
represent an alpha particle.
U  He  Th
U    Th
238
92
238
92
4
2
234
90
234
90
• 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.
• Sometimes a neutron can be split into an
electron and a proton.
• Removal of an electron from a neutron
changes the neutron into a proton
0 
1
n e  p
1
0
1
1

n   p
1
0

1
1

140
56
Ba   

140
57
La
(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.)
(cont.)
• The release of a  ray does not change
the mass number or the atomic
number
– a  ray has no mass.
•  radiation by itself does not change
the identity of the atom.
–But  ray emission usually occurs
whenever there is alpha or beta
emission.
Nuclear fission
Sometimes you can get
an atom to split by
bombarding it with
neutrons
U  n  Kr 
238
92
1
0
91
2
142
90
Ba  5 n
1
0
Can we use nuclear chemistry to make
gold?
• What isotope would you want to start with if you
were to make gold using alpha decay? Why?
• What isotope of gold would you make?
• Is this isotope stable?
• What element would you want to start with if you
were to make gold using beta decay? Explain
• Is this isotope stable?
• Do you think chemists use nuclear decay to
make gold? Why or why not?
Check-In
• What products do you expect if an
atom of actinium-227
–undergoes alpha decay?
– Write equation
– Is the formed atom stable?
–undergoes beta decay?
– Write equation
– Is the formed atom stable?
Wrap-Up
• When changes occur in the nucleus of
an atom it is called a _____ reaction.
• When an α particle is emitted from an
atom, the nucleus loses two _____ and
two ______. An α particle is the same
as a _____ atom.
• When a β particle is emitted from an
atom, the nucleus gains a(n) _____
and loses a(n) _____. A β particle is
the same as a(n) ______.