1. Nuclear Chemistry
In this chapter, we will discuss concepts that contradict what you have already learned. In a nuclear reaction, elements can change into different elements. The energy that atoms emit does not come from the electrons falling back to lower energy levels but comes from the atomic nucleus itself. And the amount of energy released in an nuclear reaction is millions of times greater than the electromagnetic radiation released from excited atoms.

2. Nuclear Chemistry Henri Becquerel (1889)
He noticed that a certain type of
rock would glow in the dark if
he left it in the sunlight for a few
hours.
Discovered that these special rocks
would cause his photographic
to appear that it had been exposed
to light.

3. Nuclear Chemistry Marie Curie (1898) Worked with Henri Becquerel
in trying to find out what was
releasing the very powerful
energy within the rocks.
She discovered that the energy
that was being emitted from the rock was from the
nuclei of some Uranium atoms. She called it Nuclear
Radiation.

4. Nuclear Chemistry Marie Curie and Henri Becquerel
They worked together in
Becquerel’s lab in Paris to
discover the exact nature
of this nuclear radiation.

5. Nuclear Chemistry 3 types of Nuclear Radiation
Alpha particles – Small particles that are emitted from the nucleus of an atom. They are the same size as a Helium atom and have a positive charge.
4 He 2

6. 3 types of Nuclear Radiation Alpha particles
Nuclear Chemistry
3 types of Nuclear Radiation
Alpha particles

7. Nuclear Chemistry 3 types of Nuclear Radiation Alpha particles
Alpha particles emitted from the atomic nucleus traveling a little slower than the speed of light.
Even though these particles have the ability to destroy soft body tissue, your skin can block them.

8. Nuclear Chemistry 3 types of Nuclear Radiation
Beta particles – Particles that are emitted from the atomic nucleus that are the size of an electron. They also have a negative charge.
Beta particles are dangerous because are traveling much faster than an alpha particle. They travel near the speed of light.
Beta particles can travel through your skin and cause tissue damage.

9. 3 types of Nuclear Radiation Beta particles
Nuclear Chemistry
3 types of Nuclear Radiation
Beta particles

10. 3 types of Nuclear Radiation Beta particles 0β -1
Nuclear Chemistry
3 types of Nuclear Radiation
Beta particles 0β -1

11. Nuclear Chemistry 3 types of Nuclear Radiation
Gamma Rays – Rays of high energy light that come from the nucleus of the atom.
Gamma Rays have no mass.
They are very dangerous. Gamma Rays can travel through 6 feet of solid concrete.

12. 3 types of Nuclear Radiation Gamma Rays
Nuclear Chemistry
3 types of Nuclear Radiation
Gamma Rays

13. 3 types of Nuclear Radiation Gamma Rays ϒ
Nuclear Chemistry
3 types of Nuclear Radiation
Gamma Rays ϒ

14. 3 types of Nuclear Radiation
Nuclear Chemistry
3 types of Nuclear Radiation

15. Nuclear Chemistry Writing Nuclear Reactions
A nuclear reaction occurs when an alpha particle, beta particle, or a gamma ray is emitted from the atomic nucleus.
Sometimes, an element can change into a different element in the process. This is called a tranmutation reaction.

16. Nuclear Chemistry Transmutation Reactions
When a C-14 atom releases an alpha particle, the carbon atom changes into a beryllium atom.
6C  2He Be

17. Nuclear Chemistry Transmutation Reactions
What will happen if C-14 releases a beta particle?
6C  -1β N

18. Nuclear Chemistry Transmutation Reactions
Write the transmutation reaction when Uranium-235 releases an alpha particle.

19. Nuclear Chemistry Transmutation Reactions Positron and Neutron Capture
A capture is when a nucleus absorbs a particle.

20. Nuclear Chemistry Transmutation Reactions Positron and Neutron Capture
A capture is when a nucleus absorbs a particle.

21. Fission – Discovered by Enrique Fermi at University of Chicago.
Nuclear Chemistry
Fission – Discovered by Enrique Fermi at University of Chicago.

22. Nuclear Chemistry
Fission

23. Nuclear Chemistry Fission
In order to initiate fission, there must be an exact amount of U-235.
This exact amount is called the critical mass.
It is about the size
of a grapefruit.

24. Nuclear Chemistry Using fission to Make Electricity
Fission of U-235 is used to produce heat in order to boil water.
The steam generated
is used to turn a
turbine that produces
electricity.

25. Nuclear Chemistry Using fission to Make Electricity
Cadmium control rods are used to absorb neutrons and slow down the fission process.
If the control rods are fully inserted into the U-235 core, the process of fission ceases.

26. Nuclear Chemistry
Fission

27. Nuclear Chemistry
Fusion

28. Nuclear Chemistry
Fusion

29. Nuclear Chemistry Rates of Radioactive Decay
Half-Life (t1/2): The amount of time required for ½ of the nuclei of a radioactive sample to emit their radioactivity.
t1/2 C-14 = 5715 years (beta decay)
t1/2 K-40 = 1,300,000,000 years (beta decay)
t1/2 U-238 = 4,500,000,000 years (alpha decay)
t1/2 Sr-90 = 28.8 years (Beta decay)
t1/2 I-131 = years (Beta decay)

30. Radioactive Half-Lives
Nuclear Chemistry
Radioactive Half-Lives

31. Nuclear Chemistry Rates of Radioactive Decay
What percentage of the original sample of a radioisotope would remain if 4 half-lives elapse?

32. Nuclear Chemistry Rates of Radioactive Decay
The half-life of Co-60 is 5.3 years. How much of a mg sample of Co-60 is left after a 15.9 year period?

33. Nuclear Chemistry Rates of Radioactive Decay
Since radioactive decay is first-order, we can use the following equation;
k = 0.693
t1/2
k = reaction (decay) constant
t1/2 = half-life of radioisotope

34. Nuclear Chemistry Rates of Radioactive Decay
If we know the initial amount and current amount of a radioisotope;
ln Nt = -kt No
k = reaction (decay) constant
t = time
Nt = number of nuclei remaining at t
No = initial number of nuclei

35. Nuclear Chemistry Energy Changes in Nuclear Reactions
Sometimes the mass of the reactants don’t equal the mass of the products in a nucleuar reaction.
Where did the mass go?
E = mc2
E = Energy
m = mass
c = speed of light (3.00 x 109 m/s)

36. U-238  Th-234 + alpha particle
Nuclear Chemistry
Energy Changes in Nuclear Reactions
Calculate the energy change for the following nuclear reaction;
U  Th alpha particle
U-238 = amu
Th-234 = amu
Alpha particle = amu