Nuclear Reactions
There are __________ ways to identify elements by isotope.
1 – ____________
The element’s _______ is followed by its
_____________.
Ex: lead – 207, carbon-13, lithium-7…
Give the name of the following isotopes:
a. 10 p+, 10e-, 11 no
c. 1 p+, 1e-, 0 no
b. 20 p+, 18e-, 22 no
d. 32p+ , 36 e- , 38no
2 – ________ ____________ The chemical symbol is “surrounded” by
data.
Mass Number
Atomic Number
Ex:
27
13
Charge
Symbol
Al
This symbol shows the aluminum-27 isotope.
There is no charge on this atom
13 p+ (atomic # is 13) 13 e- (no charge)
Ex:
31
15
P
+
-3
15 p (atomic # is 15)
14 no (atomic mass = 27)
This symbol shows the phosphorous-31 isotope.
The charge on this anion is -3.
18 e- (-3 charge)
16 no (atomic mass = 31)
Identify the name the #p+, #no, and # e- for the following:
40
20
+2
Ca
Si
207
82
Pb
35
17
-1
Cl
4
2
He
PA
Nuclear Reactions
Important Facts to KNOW;
1- Nuclei are unstable because there are ___ _______ _________________
.
2- There are four types of nuclear ______________ that are common in nuclear reactions.
a. They are NOT elements or atoms, just forms of radiation.
3- ______________ is when one unstable nucleus splits into two or more pieces
4- ___________ is when two nuclei combine into one nuclei
5- Nuclear reactions also occur when two nuclei ________ , but then ___________ into two other nuclei.
Type
Symbol
Mass Charge
(amu)
notes
Neutron
Alpha
Beta
Gamma
To balance a nuclear reaction…

Keep in mind the _____ __ ________________ __ _______ must still be observed.
 The ______ ___________ must sum to the same value on each side of the equation.
 The __________ __________ must sum to the same value on each side of the
equation.
Examples of different types of decay:
Neutron Decay:
210
84
1
92U 
238
19
9
209
Po  0 n + 84 Po
Alpha decay:
Beta Decay:
Explain
90 Th + 2 
234
4
+2
F  +-1+ 10Ne
0
19
Complete following nuclear reactions. Are alpha, beta or neutron decays?
a.
210
85
c.
At  ____ + -1  
0
208
83
207
Bi  ___ + 83 Bi


b. 222 Rn
86
 ___ + 2
4
+2
Nuclear Reactions
Half-Life
The length of a half-life describes ___________________________________________
The shorter the half-life, the ___________________________________________
The longer the half-life, the___________________________________________
amount
Time (in half lives passed
400 grams
to - initial observation starting time
t1 - the first half life
t2 - the same amount of time between to and t1
t3 - again, the same amount of time between to and t1...
or between t1 and t2...
t4 - again, the same amount of time between to and t1...
or between t1 and t2... or t2 and t3
t5 - again, the same amount of time between to and t1...
or between t1 and t2... or t2 and t3 ... or t3 and t4
t6 - again, the same amount of time between to and t1...
or between t1 and t2... you get it...
Graph the relationship between amount (in grams) and number of half lives passed
400
300
Amount
(grams)
200
100
0
0
1
2
What type of relationship is this?
3
4
5
Number of half-lives
6
7
8
1) If we start with 48 atoms of a radioactive substance, how many would remain …
a. After one half-life?
c. after three half-lives?
b. after two half-lives?
d. after four half-lives?
Use the following chart to answer questions 2-5
Radioactive Isotope
Radon-222
Iodine-131
Radium-226
Carbon-14
Plutonium-239
Uranium-238
Half Life
4 days
8 days
1600 years
5730 years
24,120 years
4,470,000,000 years
2) If a sample starts with 8000 atoms of radium-226,
how much would remain after 3,200 years?
3) If a sample starts with 20 grams of plutonium-239,
how many grams would remain after 48,240 years?
4) If a sample was found with 60 atoms of radon-222,
how many were there 12 days ago?
5) If a sample was found with 3.25 grams of iodine-131,
what mass was there 32 days ago?