UNIT 2
NUCLEAR REACTIONS
2.2 What nuclear stability and radioactive decay?
May 16, 2011
DO NOW:
What are the types of radiation?
Alpha
Beta
Gamma
Positron
What is the decay mode for krypton-85?
TABLE N
Beta
-β
NUCLEAR REACTIONS
• A nuclear reaction is a reaction that involves a
CHANGE in an atom’s IDENTITY.
• Nuclear reactions occur because the nucleus is
UNSTABLE
NUCLEAR STABILITY
Depends on
Proton to Neutron Ratio
Proton to Neutron
Ratio ≠ 1:1
Proton to Neutron
Ratio = 1:1
Spontaneous Decay
STABLE NUCLEUS
Isotope
(or RADIOISOTOPE)
will undergo decay
Neutron to proton ratio
Makes it stable
NOTE
• Elements with an atomic number greater than
82 are always radioactive.
Going back to our key questions:
• What makes something radioactive?
When the Neutron to Proton Ratio is not 1:1
When the Nucleus is UNSTABLE
• What happens when something is
radioactive?
It emits energy as it decays into a more stable
isotope
STABILITY BAND
TYPES OF RADIOACTIVE DECAY
Term
Law of
Conservatio
n of Mass
Definition
Energy may change from one form to another,
but it is neither created nor destroyed.
CHEMICAL EQUATIONS
210
4
206
Po
84
14
c
6
He + 82 Pb
0
14
e
+
N
-1
7
11
0
C
6
2
e
+1
+
11
B
5
TRY THIS!
Write the alpha decay nuclear equation
for Bi-214 (atomic number 83).
214
Bi
83
4
210
He
+
Ti
2
81
TRY THIS!
Write the decay reaction for gold-198.
198
Au
79
0
e
-1
+
198
Hg
80
TRY THIS!
Write the decay reaction for iron-53.
53
Fe
26
0
e
+1
+
53
Mn
25
TRANSMUTATIONS
These reactions are called
TRANSMUTATIONS because we start
out with one element and change it
to another element.
INDEPENDENT PRACTICE
• Complete the worksheet
• HOMEWORK: READ THE ARTICLE AND WRITE
A SUMMARY (answer all the questions
listed)