Transcript Balancing Nuclear Equations - Williamsburg High School for

Williamsburg High School for Architecture and
Design
Mr. Quinn and Ms. Tom
9/30/13
How do I balance natural
decay equations?



4=2+2
Y = mx + b
14 C → 14 N +
6
7
0
-1e
Atomic number (Z) = number of protons in nucleus
Mass number (A) = number of protons + number of neutrons
= atomic number (Z) + number of neutrons
Mass Number
A
Atomic Number
Z
proton
1p
1
or
1H
1
neutron
1n
0
X
Element Symbol
electron
0e
-1
or
 particle
positron
0
-1
0e
+1
or
0
+1
4He
2
or
A
1
1
0
0
4
Z
1
0
-1
+1
2
4
2
23.1
Balancing Nuclear Equations
1. Conserve mass number (A).
The sum of protons plus neutrons in the products must
equal the sum of protons plus neutrons in the reactants.
235U + 1n
92
0
138Cs + 96 Rb + 2 1n
55
37
0
235 + 1 = 138 + 96 + 2x1
Balancing Nuclear Equations
2. Conserve atomic number (Z) or nuclear charge.
The sum of nuclear charges in the products must equal the
sum of nuclear charges in the reactants.
235
92
U +
1n
0
138
96
55
37
Cs +
92 + 0 = 55 + 37 + 2x0
Rb + 2 1n
0
212Po
decays by alpha emission. Write the balanced
nuclear equation for the decay of 212Po.
4He
alpha particle -
212Po
2
4He
2
84
or
4
2
AX
+
Z
212 = 4 + A
A = 208
84 = 2 + Z
Z = 82
212Po
84
4He
2
+
208Pb
82
23.1
How do I balance artificial
transmutation equations?
II. Nuclear Transmutations
•Nuclear reactions that are induced in a way that nucleus is struck by a
neutron or by another nucleus (nuclear bombardment)
a.Positive ion bombardment
- alpha particle is the most commonly used positive ion
- uses accelerators
Examples:
14 N + 4 He → 17 O + 1 H
7
2
8
1
9
4 Be
+ 42 He → 126 C + 10n
II. Nuclear Transmutations
Neutron bombardment
- neutron is bombarded to a nucleus to form a new nucleus
- most commonly used in the transmutation to form synthetic isotopes
because neutron are neutral, they are not repelled by nucleus
Example:
58
26
Fe + 10 n → 5926 Fe →
59
27 Co
+ 0-1 e
Transuranium elements
-Element with atomic numbers above 92
-Produced using artificial transmutations, either by:
a. alpha bombardment
b. neutron bombardment
c. bombardment from other nuclei
Examples:
a.
b.
239 Pu + 4He
94
2
238 U
92
+
1n
0
239 Pu + 0 e
94
-1
c.
238 U
92
+
14N
7
242 Cm + 1n
96
0
239 U
92
239 Np
93
+
247 Es +
99
0
-1 e
5
1n
0