IONISING RADIATION UNDERSTANDING THE NATURE OF IONISING RADIATION
At the end of this lesson YOU should
know the different types of ionising radiations and their properties
Be able investigate the penetrating ability of different types of ionising radiation through different thickness of materials
Know and explain the reason for the different penetrating abilities of different types of ionising radiation through paper, aluminium and lead
Starter Activity 1. What is Radiation? 2. What is background radiation? Radiation is all around us. True or False?
What is Radiation? Radiation is energy. It travels through space in the form of particles or waves. Radiation is everywhere. It is in the air we breathe, the water we drink, and the food we eat. This makes up the "background radiation" that we are all exposed to everyday. IONISING RADIATION The energy released from radioactive atoms is ionising radiation.
IONISING RADIATION Ionizing radiation is radiation that has sufficient energy to remove electrons from atoms.
Radiation is all around us. That is called background radiation.
Ionizing radiation comes from radioactive materials
It is invisible and not directly detectable by human senses.
instruments such as Geiger counters are usually required to detect its presence.
RADIATION TYPES Unstable atoms emit (give radiation) from their NUCLEI. An unstable nucleus can emit alpha, beta and gamma radiation. Note the properties of the three types of radiation shown below NOTE
QUICK RECAP Which one of the three types of radiation is: 1.The hardest to stop. 2.The easiest to stop. 3. Explain why different types of radiation are absorbed by different amounts in different material ALPHA BETA GAMMA
Penetrating Power of Radiation Complete the table to summarise the properties of alpha, beta and gamma radiation. property alpha beta gamma ionising power range in air stopped by Electromagnetic radiation?
RADIOACTIVE DECAY Radioactive decay is the process in which an unstable atomic nucleus spontaneously loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom of one type, called the parent nuclide transforming to an atom of a different type, named the daughter nuclide. NOTE FACT
RADIOACTIVE DECAY Radioactive elements have unstable nuclei, meaning they are transformed into other elements. When an unstable atom emits radiation it undergoes radioactive decay and becomes more stable. NOTE
TYPES OF DECAY Alpha decay: Participating particle is alpha (A=4, Z=2) emitted from the nucleus. It’s important you learn to work this out Beta negative decay (A=0, Z=1) and the daughter nucleus is (A, Z+1) Beta positive decay (A=0, Z=1) and the daughter nucleus is (A, Z-1) NOTE NOTE NOTE
RESEARCH THE ANSWERS TO THE FOLLOWING QS.
What does an alpha particle consist of?
How does the mass number of an atom change if it undergoes alpha decay?
How does the atomic number of an atom change if it undergoes alpha decay?
How do nuclei with too many neutrons try to become unstable?
What happens during beta decay? (Which particle changes?)
What is gamma radiation?
Which of the types of radiation is most destructive?
Effect of Radiation on living Organisms
Why is ionising radiation dangerous to humans?
What are the effects of each type of radiation on human cells if they do enter the body?
a). Alpha radiation b). Beta c). Gamma
Effect of Radiation on living Organisms Effect of Radiation on living Organisms
Because of the hazards, you are not allowed to use radioactive sources yourself. Discuss the risks associated with use of ionizing radiation? Your TASK
Four Primary Types of Ionizing Radiation
Gamma rays (or photons)
X-Rays (or photons)
Types or Products of Ionizing Radiation or X-ray neutron