1. Nuclear Chemistry

2. The Nucleus
Remember that the nucleus is comprised of the two nucleons, protons and neutrons.
The number of protons is the atomic number.
The number of protons and neutrons together is effectively the mass of the atom.

3. Isotopes
Not all atoms of the same element have the same mass due to different numbers of neutrons in those atoms.
There are, for example, three naturally occurring isotopes of uranium:
Uranium-234
Uranium-235
Uranium-238

4. Radioactivity
It is not uncommon for some nuclides of an element to be unstable, or radioactive.
We refer to these as radionuclides.
There are several ways radionuclides can decay into a different nuclide.

5. B. Nuclear Binding Energy
Unstable nuclides are radioactive and undergo radioactive decay.
C. Johannesson

6. Types of Radioactive Decay

7. A. Types of Radiation 2+ 1- 1+ Alpha particle () Beta particle (-)
helium nucleus
paper 2+
Beta particle (-)
electron 1-
lead
Positron (+)
positron 1+
concrete
Gamma ()
high-energy photon
C. Johannesson

8. Alpha Decay
Alpha decay is the loss of an -particle (a helium nucleus). He 4 2 U
238 92

234 90 He 4 2 +

9. Beta Decay
Beta decay is the loss of a -particle (a high energy electron).  −1 e or I
131 53 Xe 54
 + e −1

10. e C B e Positron Emission
Some nuclei decay by emitting a positron, a particle that has the same mass as but an opposite charge to that of an electron. e 1 C 11 6
 B 5 + e 1

11. Gamma Emission
This is the loss of a -ray, which is high-energy radiation that almost always accompanies the loss of a nuclear particle. 

12. Electron Capture (K-Capture)
Addition of an electron to a proton in the nucleus is known as electron capture or K-capture.
The result of this process is that a proton is transformed into a neutron. p 1 + e −1
 n