1. What is radioactivity? lecture 9.1 Gamma ray bursts from a star collapsing into a Black Hole

2. Nuclear radiation: energy and matter released from the nucleus of an atom. Nuclear radiation: energy and matter released from the nucleus of an atom. An element that does this is called radioactive An element that does this is called radioactive All elements over at.# 80 are radioactive, and isotopes of other elements can be also. All elements over at.# 80 are radioactive, and isotopes of other elements can be also.

3. 4 types of radiation Alpha, beta, gamma ray and neutron

4. Alpha Alpha particles are made of 2 protons and 2 neutrons (a Helium nucleus) Alpha particles are made of 2 protons and 2 neutrons (a Helium nucleus) They have a (+) charge and a mass of 4 amu. They have a (+) charge and a mass of 4 amu. They travel only short distances They travel only short distances

5. Americium decays into Neptunium and alpha radiation Photograph of alpha particles Alpha decay

6. Beta Beta particles are electrons made when a neutron decays. Beta particles are electrons made when a neutron decays. They have no mass and a (-) charge They have no mass and a (-) charge They can be stopped by 3mm of wood They can be stopped by 3mm of wood Capable of ionizing other molecules Capable of ionizing other molecules

7. Gamma Gamma rays are not matter, they are made of high-energy photons. Gamma rays are not matter, they are made of high-energy photons. They have no mass or charge They have no mass or charge They penetrate and ionize matter They penetrate and ionize matter Marie Curie Black holes release gamma radiation

8. Neutron radiation Neutrons can be emitted from an unstable nucleus Neutrons can be emitted from an unstable nucleus They have no charge, but can penetrate matter. They have no charge, but can penetrate matter. Thick concrete or 15cm of lead will stop them Thick concrete or 15cm of lead will stop them

9. Quiz: name the types of radiation, their charge, and the Materials that can stop them: