Radioactivity

4. Why does the atom do this? the nucleus of an atom attempts to become more stable In some instances, a new element is formed and in other cases, a new form of the original element, called an isotope, appears. this process of change is often referred to as the decay of atoms. The rate of Radioactive decay is described in half-lives.

5. Energy is released during radioactive decay

6. Types of Nuclear Radiation When an unstable nucleus decays, particles and energy are given off from the decaying nucleus. a and ß radiation is in the form of particles ? radiation is in the form of waves-kind of like light but higher frequency

8. Alpha particles consist of two protons and two neutrons, identical to the nucleus of a helium atom. A sheet of paper or a person’s surface layer of skin will stop them. Alpha particles are only considered hazardous to a person’s health if they are ingested or inhaled and thus come into contact with sensitive cells such as in the lungs, liver and bones.

10. Beta particles are electrons emitted from the nuclei of many fission products.

12. Gamma rays are a form of electromagnetic radiation (like light, radio, and television) that come from the nucleus of a radioactive atom. Occurs when an unstable nucleus emits electromagnetic radiation. The radiation has no mass, and so its emission does not change the element. They penetrate matter easily and are best stopped by water or thick layers of lead or concrete. Gamma radiation is hazardous to people inside and outside of the body.

19. Fission and Fusion

24. Half Life is the amount of time it takes for half of the nuclei in a sample to decay

26. mass number Carbon occurs naturally in three isotopes. All of these atoms have the same number of protons but different numbers of neutrons. The number of neutrons and protons determines the mass, so the masses are different. 14C is radioactive.

27. 14C Radioactive 14C acts chemically just like 12C, so it becomes incorporated into plants an animals. When the animal/plant dies the 14C begins to decay into 14N at a know rate, so we can determine how long ago the organism died. This is called Carbon Dating. It’s only good for about 50,000 years.

28. The half life of 14C is 5,730 years. If a sample originally contained 100 g, how much would be left after 11,460 years?

30. Older Dating Methods The isotopes 235U and 238U can be used to date objects billions of years old. 235U has a half life of 704 million years. 238U has a half life of 4.5 billion years. Mainly used for rocks.

31. Geiger Counter Used to measure radiation. The more intense the radiation the more “clicks”.