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