nuclear chemistry lesson 1: islands of stability
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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:
• 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?
Cu63
29Au
197
79
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.
Plot this isotope
# of protons?
# of neutrons?
4119K
Island of stability
Band of stability
protons = neutrons
• Nuclear chemistry study of atom nucleus
• Band of stability range in neutron # for given proton # for naturally occurring isotopes
Notes
• 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
Stable isotope?
> 10+15 s 10-01 s 10+10 s 10-02 s 10+07 s 10-03 s 10+05 s 10-04 s 10+04 s 10-05 s 10+03 s 10-06 s 10+02 s 10-07 s 10+01 s 10-15 s 10+00 s < 10-15 s
2412
15260
19577
9035
23892
19177
Mg
Nd
Ir
Br
U
Ir
p = 12n = 12
p = 92n = 60
p = 118n = 77
p = 35n = 55
p = 92n = 146
p = 77n = 114
2412
15260
19577
9035
23892
19177
Mg
Nd
Ir
Br
U
Ir
p = 12n = 12
p = 60n = 92
p = 77n =118
p = 35n = 55
p = 92n = 146
p = 77n = 114
Worksheet6. 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.
Worksheet8. 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
No Yes Yes No Yes
162 75 112 260 30063 33 56 88 115 ????Eu As Ba Ra
• 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
Notes
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