Transcript Band of stability

Nuclear Chemistry
Lesson 1:
Islands of Stability
Nuclear Chemistry – Bell work
The isotope notation for an atom of copper and
an atom of gold are given below:
63
197
29
79
Cu
Au
• How could you change a copper atom into a
gold atom?
• What would you need to change? Give specific
numbers.
• Why is this change called a nuclear reaction?
The Big Question
• What is the range of the number of neutrons
found in isotopes of various elements?
• Goal - Determine how many neutrons are
required to make a stable element with a
given number of protons.
Island of stability
Plot this isotope
41
19
K
# of protons?
# of neutrons?
protons = neutrons
Band of stability
Notes
• Nuclear chemistry
study of atom
nucleus
• Band of stability
range in neutron #
for given proton # for
naturally occurring
isotopes
Stable isotope?
• Inside gray area?
Stable isotope
• On edge?
Radioactive
• Outside?
Isotope not stable
Not an element
• What is an element?
– Isotope detected?
– Element 118 discovery
last fall
– Lasted 0.05 milliseconds
> 10+15 s
10+10 s
10+07 s
10+05 s
10+04 s
10+03 s
10+02 s
10+01 s
10+00 s
10-01 s
10-02 s
10-03 s
10-04 s
10-05 s
10-06 s
10-07 s
10-15 s
< 10-15 s
24
12
Mg
Nd
p = 92
n = 60
Ir
p = 118
n = 77
Br
p = 35
n = 55
152
60
195
77
90
35
p = 12
n = 12
238
92
p = 92
n = 146
191
77
p = 77
n = 114
U
Ir
24
12
Mg
Nd
p = 60
n = 92
Ir
p = 77
n =118
Br
p = 35
n = 55
152
60
195
77
90
35
p = 12
n = 12
238
92
p = 92
n = 146
191
77
p = 77
n = 114
U
Ir
Worksheet
6. Imagine a chemist was
trying to create an atom
with 60 protons and a
mass number of 155.
Would this be possible?
Why or why not?
7. Where on the graph
would you expect the
other isotopes of
magnesium to be
located (magnesium-25
and magnesium-26)?
Explain.
Worksheet
8. If an element had 90
protons, how many
neutrons would be a
good number for it to
have in order to be
considered a stable
element? What element
would this be?
9. What do you suppose
that little island of gray
on the graph
represents?
Check-In
• Use your graph to
determine how many
neutrons you would
need to make a stable
element with 75
protons.
• How many neutrons
would make a
radioactive element
with 75 protons?
Answer to #10
162
63
Eu
No
75
33
As
Yes
112
56
Ba
Yes
260
88
Ra
No
300
115
????
Yes
Notes
• Radioactive elements lose pieces of the
nucleus over time.
• Atoms that exist for a long time are called
stable.
• Radioactive atoms disappear over time and are
called unstable.
• Any isotope that lasts long enough to be
detected and measured qualifies as an element
–Element 118 discovery last fall
–0.05 milliseconds