1. 10.1 Radioactivity

2. Nuclear Decay… Atoms of one element can change into atoms of a different element altogether. An unstable atom has excess internal energy, with the result that the nucleus can undergo a spontaneous change towards a more stable form. Radioisotopes are atoms that contain an unstable nucleus and will change into another isotope over time. Scientists can estimate the age of fossils by looking at nuclear decay.

3. Radioactivity… is the process in which an unstable atomic nucleus emits charged particles and energy.

4. 3 Types of Nuclear Radiation 1. Alpha Particles 2. Beta Particles 3. Gamma Rays

5. Nuclear Radiation… charged particles and energy that are emitted from the nuclei of radioisotopes. If an element decays and emits an alpha or beta particle, it becomes a new element. Gamma rays are often emitted with alpha or beta radiation also, as the nucleus decays to a less excited state.

6. Alpha Particle Positively charged particle made up of two protons and two neutrons—the same as a helium nucleus. When a uranium-238 sample decays, it emits alpha particles. An alpha particle has a 2+ charge. Symbol for alpha: 

7. Beta Particle negatively charged radiation electron emitted by an unstable nucleus A beta particle is assigned an atomic number of –1. Symbol for beta: 

8. Gamma Ray Penetrating ray of energy emitted by an unstable nucleus. Gamma radiation has no mass and no charge. Like X-rays and visible light, gamma rays are energy waves that travel through space at the speed of light. Symbol for gamma: 

10. Units of Radioactivity… The amount of radioactive material is given in becquerel (Bq), a measure which enables us to compare the typical radioactivity of some natural and other materials. A becquerel is one atomic decay per second.

11. Radioactivity of some natural and other materials 1 adult human (100 Bq/kg) 7000 Bq 1 kg of coffee 1000 Bq 1 kg superphosphate fertiliser 5000 Bq The air in a 100 sq metre Australian home (radon) 3000 Bq The air in many 100 sq metre European homes (radon) up to 30 000 Bq 1 household smoke detector (with americium) 30 000 Bq Radioisotope for medical diagnosis 70 million Bq Radioisotope source for medical therapy 100 000 000 million Bq (100 TBq) 1 kg 50-year old vitrified high-level nuclear waste 10 000 000 million Bq (10 TBq) 1 luminous Exit sign (1970s) 1 000 000 million Bq (1 TBq) 1 kg uranium 25 million Bq 1 kg uranium ore (Canadian, 15%) 25 million Bq 1 kg uranium ore (Australian, 0.3% 500 000 Bq 1 kg low level radioactive waste 1 million Bq 1 kg of coal ash 2000 Bq 1 kg of granite 1000 Bq

12. Electromagnetic Radiation Consist of electromagnetic waves Most of these are harmless