Balancing Nuclear Equations
Name:
Period:
There are two types of nuclear reactions: Fission, where a nucleus breaks into two or more pieces, and
fusion where two or more nuclei combine to form a new element. In nuclear reactions, only the nucleus is
involved. Electrons are ignored. Some atomic nuclei are inherently unstable and spontaneously change or
“decay”. There are four types of decay:
Type
Symbol
Alpha
α
Betae- emission
Beta+
e- capture
Gamma
βelectron
β+
Positron
γ
Charge
of Mass(AMU)
particle
+2 (He
4
nucleus)
-1
0
Effect on
Effect on Atomic
Atomic #
Mass
decrease by 2
decrease by 4
Strength
increase by 1
0
Stopped by
paper
Aluminum Foil
+1
0
decrease by 1
0
Aluminum Foil
none
none
none
none
Lead
The net result of α, β- or β+ decay is a new element. In b- decay, a neutron decays into a p+ and an ewhich is then ejected. In β+ decay a p+ captures an e- and transforms into a neutron. But despite the nature
of the reaction the law of conservation of matter still applies and the equations are balanced the same way.
Note α particle is a helium nucleus!
Another type of reaction occurs when something impacts a nucleus. These reactions result either in
the nucleus splitting (fission) or the combination of two or more nuclei to form a third, different nucleus
(fusion).
Balancing Nuclear Equations: Matter must be conserved including all p+ & n˚. Example:
Decay reaction (α decay)
Fission Reaction
Fusion Reaction:
219
86
Rn"24 He+ 215
84 Po
1
0
35
17
92
141
1
n+ 235
92 U"36 Kr+ 56 Ba +30 n
2
3
4
o
36
Cl+11H"18
Ar another example 1 H+ 1H"2 He + n
!
!
Practice
Fill in the missing !
symbol and name the reaction:
!
!
!
!
1.
3
1
H " ___________+ #10e
2.
232
92
3.
144
58
4.
65
30
5.
40
19
U"228
90Th + ___________
Ce"144
59 Pr+ ___________
Zn " ___________+ +10e
40
K"18
Ar + ________
!
6.
7
4
Be"47 Be + ________
7.
1
0
141
92
n+ 235
92 U " __________" 55 Cs+ 37 Rb + ___________
8.
222
86
9.
129
53
I"129
54 Xe + ________
10.
239
94
Pu " _________+ 24 He
11
15
8
!
Rn " _______+ 24 He
!
!
!
O"157 N + ________
!
12. Write a balanced nuclear equation for each decay process indicated.
a. The isotope Th-234 decays by an alpha emission.
!
b. The isotope Fe-59 decays by a beta emission.
c. The isotope Tc-99 decays by a gamma emission.
d. The isotope C-11 decays by a electron capture.
Balance these equations: Note 24 He is the only stable isotope of helium.
13.
!
1
1
H+ 37Li "
14.
7
4
Be + n o " ______ H + _______He
!
15. What is the balanced nuclear equation for the reaction of curium-246 with carbon-12 to produce
nobelium-254 and four neutrons?
!
16. What is the balanced nuclear equation for the reaction of californium-250 with boron-10 to produce
lawrencium-258 and two neutrons?
1.
3
1
2.
232
92
3.
144
58
!
4.
!
!
!
!
!
!
!
H"23 He+ #10e
β- decay
4
U"228
90Th+ 2 He
α decay
0
Ce"144
Pr+
59
#1e
β- decay
65
30
65
Zn"29
Cu+ +10e
β+ decay
5.
40
19
40
K"18
Ar+ +10e
β+ decay
6.
7
4
Be"47 Be + #
γ decay
7.
1
0
236
141
92
1
n+ 235
U"
U"
Cs+
Rb
+3
92
92
55
37
0n
8.
222
86
4
Rn"218
84 Po+ 2 He
α decay
9.
129
53
0
I"129
Xe+
54
#1e
β- decay
10.
239
94
4
Pu"235
92 U+ 2 He
α decay
15
15
0
11. 8 O" 7 N+ +1e
!
!
Fission
β+ decay
12.
!
!
a.
234
90
4
Th"230
Ra+
88
2 He
b.
59
26
c.
99
43
Tc"99
43Tc + #
d.
11
6
1
7
C+ "10e#115 B
8
13. 1 H+ 3 Li "2 2 He or 4 Be
!
7
!
4
59
Fe"27
Co+ #10e
1
14. 4 Be+ 0 n
!
246
15. 96
!
250
16. 98
"2 21 H + 42 He!
or 11H + 31H+ 42 He
254
Cm+126 C"102
No +4 01n
258
Cf +105 B"103
Lr +2 01n