1. 9/14 Opener
What should I do if I need to go to the bathroom in Miss D’s class?
Check to make sure no one is in the bathroom (only one person out at a time)
Sign out with your name and time out
Let Miss D know you are leaving the classroom
Take the bathroom pass
Upon return sign in with the time
Failure to do this will result in loss of bathroom privileges

2. Nuclear Radiation and Transformation
Chapter 25.1 and 25.2

3. Radioactivity
In 1896 French chemist Becquerel, working with Marie and Pierre Curie discovered and named radioactivity
Radiation is the penetrating rays and particles emitted by a radioactive source, like uranium
Radioisotopes gain stability by undergoing changes accompanied by the release of large amounts of energy
This process cannot be speed up, slowed down, or turned off.
Unaffected by temperature, pressure, or catalysts
An unstable nucleus releases energy by emitting radiation during the process of radioactive decay

4. Types of Radiation Alpha Radiation Beta Radiation Gamma Radiation
A helium nuclei is emitted from a radioactive source, contains two protons, and two neutrons with a double positive charge
42He or α
Ex. U Th He
Beta Radiation
A neutron breaks into a proton, which stays in the nucleus, and a fast moving electron that is released
0-1e or β
C N e
Gamma Radiation
A high-energy photon emitted by a radioisotope, γ
Have no mass or electrical charge
Th Ra + He + Y 4 2
238 92
234 90 14 6 14 7 -1
230 90
226 88 4 2

5. Types of Radiation

6. Nuclear Stability and Decay
There are different nuclei and only 264 are stable
The stability of a nucleus depends on neutron-to- proton ratio
Stable nuclei are in a region called the band of stability
The n-to-p ratio determines the type of decay
A positron is a positive particle with the mass of an electron
A proton changes to a neutron
Mass is NOT conserved. A small amount is converted to energy.

7. Half-Life
Half-Life is the time required for one-half of the nuclei of a radioisotope sample to decay to products
After each half-life, half of the existing radioactive atoms have decayed into atoms of a new element

8. Transmutation Reactions
Transmutation is the conversion of one element to an atom of another element
This can occur by radioactive decay or by particles bombarding the nucleus of an atom
Ex: uranium-238 undergoes 14 transmutations before reaching a stable isotope