1. LAB #1 Radioactivity RADIOACTIVITY: is spontaneous transition of an atomic nucleus from a higher energy to a lower energy state. This transition is accompanied by the release of a charged particle and/or electromagnetic wave from the atom. Radioactivity and radioactive properties of nuclides are determined by nuclear considerations only, and independent of the chemical and physical states of the radionuclide.

2. :Nuclear Stability How do we know if something is going to be radioactive OR not? Strong Nuclear Force: Force that acts on subatomic particles that are extremely close together. Strong Nuclear Force >> repulsion of proton feeling from each other The neutrons help keeping the nucleus together. To understand the factors the has effect on the nuclear stability, we need to understand the strong nuclear force. the strong nuclear force have to negate repulsion of two protons. Strong Nuclear Force is less when there are many protons. wHy?!

3. 2 346 78 9 10 11 1213141516 1718 19 202122 23 24 252627 28 29303132 33 34 35 3637 38 394041 424344 45 46 47 48 4950 51 52535455 565758 59 6061 62 63 6465 666768 69 70 7172 73 747576 78 79 80 81 Z= 82 83 8483

4. band of stability

5. Something you need to know! Atoms that have low atomic # are tend to be stable when n/p 1:1 And high atomic # when n/p 1.5:1 1:1 neutron-to-proton ratio 1.5:1 neutron-to-proton ratio

6. Neutrons to Protons Ratio (N/P) So, Nuclear Stability depends on: #Neutrons are more than 83 The mass–energy relationship

7. Isobars Isotopes Nuclides' classification Isotones Side note! isomers Mass Number (Z+N) Atomic number (# of protons) (# of neutrons) Nuclide symbol

8. Isobars Isotopes Isotones isomers Isobars Isotopes Isotones