1. Unit 4
Nuclear Chemistry

2. What is it? Deals with the nucleus inside of an atom
Nucleus contains most of the mass
Nucleus has a positive charge

3. Nuclear Forces NUCLEONS- the protons and neutrons of a nucleus
NUCLIDE- General term applied to a specific nucleus with a given number of protons and neutrons

4. Nuclear Stability Energy is required to hold a nucleus together
If protons and neutrons come together to form a nucleus, energy is RELEASED
Proton + Neutron nucleus + energy

5. Binding Energy
NUCLEAR BINDING ENERGY- the energy released when a nucleus forms
A LARGE, LARGE, LARGE AMOUNT OF ENERGY!!!

6. Rules for Determining Stability
1. All stable nuclei have a number of neutrons that is equal or greater than the number of protons
2. A nucleus with a neutrons/protons ratio that is too large or too small is unstable
Nuclei with even numbers of neutrons and protons are more stable

7. More rules… Nuclei with special numbers (2,8,20,28,50,82,126)
No atoms that have atomic numbers larger than 83 and mass numbers larger than 209 are stable

8. Nuclear Change
Nuclear reactions can change one element into another element
The rays and particles emitted are called radiation.
Transmutation: The conversion of one element into another

9. Beta Decay
Beta radiation is radiation that has a negative charge and emits beta particles
Each beta particle is an electron with a 1– charge.
Beta radiation is a stream of fast moving particles with greater penetrating power—a thin sheet of foil will stop them.

10. How does this happen?
1. The neutron emits a high-energy electron (beta particle)
2.This causes the neutron to change to a proton
3. The atomic number increases by 1, changing the element
4. Mass number does not change

11. Example of Beta Decay

12. Alpha Decay
Used when there is a large neutron/proton ratio, large mass numbers and atomic numbers
Alpha particles are emitted
Mass number decreases by 4, atomic number decreases by 2

13. Alpha Decay
Alpha particles have the same composition as a helium nucleus—two protons and two neutrons.
Because of the protons, alpha particles have a 2+ charge.
Alpha radiation is not very penetrating—a single sheet of paper will stop an alpha particle.

14. Example

15. Gamma Radiation Gamma ray= energy that is released
Gamma rays are high-energy radiation with no mass and are neutral.
Gamma rays are highly penetrating because they have no charge and no mass.

16. Nuclear Fission
FISSION- a heavy nucleus splits into 2 smaller nuclei, both of which are more stable than the original
Used to create nuclear power

17. Nuclear Fusion
FUSION- when small nuclei combine to form a larger, more stable nucleus
This is how stars are made!

18. Positive Effects of Nuclear Chemistry
Medicine
X-rays
Nuclear power

19. Negative affects of Nuclear Chemistry
Nuclear Bomb
Radiation exposure
Birth defects
Cancer