There are quite a few different types of radiation, and we are going to look at all of the ones that you are required to know for the exam in this section. We are going to look at the make-up, sizes, distance that they travel and ionising effects of each of these different types of radiation. Ionising refers to how easy it is for the radiation to take electrons from other particles/ atoms, which results in the particles/ atoms becoming ions (an ion is a charged particle).
Alpha Radiation
Alpha radiation is where an alpha particle is emitted from the nuclei of an atom. An alpha particle is made up of 2 protons and 2 neutrons; it is a helium nucleus. The atomic number for an alpha particle is 2 (as it has 2 protons), and the mass number is 4 (as there are 2 protons and 2 neutrons; 2 + 2 = 4). The symbol for an alpha particle with the atomic number and mass number is shown below (the atomic number is the bottom number and the mass number is the top number).
Alpha radiation is where an alpha particle is emitted from the nuclei of an atom. An alpha particle is made up of 2 protons and 2 neutrons; it is a helium nucleus. The atomic number for an alpha particle is 2 (as it has 2 protons), and the mass number is 4 (as there are 2 protons and 2 neutrons; 2 + 2 = 4). The symbol for an alpha particle with the atomic number and mass number is shown below (the atomic number is the bottom number and the mass number is the top number).
Out of all of the different types of radiation, alpha radiation is the largest and heaviest. Alpha radiation only travels a few centimetres in air and is stopped by paper. Alpha radiation is strongly ionising because their size means that they tend to hit other particles, which knocks off electrons from these particles resulting in the particles that the alpha radiation hits becoming ions. Another reason why alpha radiation is strongly ionising is because alpha particles have a charge of 2+. They have this charge because they have 2 protons and no electrons.
Beta Radiation
Beta radiation occurs when a nucleus of an atom has too many neutrons. During beta radiation, a neutron turns into a proton and an electron; the proton is kept in the nuclei of the atom and the electron is fired out of the nuclei at high speed. The electron that is fired out is known as a beta particle. As it is an electron, it will have a mass number of 0 (the top number) and an atomic number of -1 (electrons are negatively charged, so the atomic number is -1). We can write beta radiation as β or e-. The two symbols and the numbers for beta radiation are shown below.
Beta radiation has characteristics that are in-between alpha and gamma radiation. They are moderately ionising, but not as ionising as alpha radiation. They have virtually no mass. They can penetrate moderately far into materials before colliding. They have a range of a few metres in air, and they are stopped by a sheet of aluminium around 5 mm thick.
Neutron Emission
Sometimes it will be the case that the nuclei of an atom will emit a neutron. A neutron has a charge of 0 and a mass of 1. This means that the atomic number for a neutron emission is 0 (bottom number) and the mass number is 1 (top number). We use the symbol n to display a neutron emission and the symbol with the numbers for it is shown below.
Sometimes it will be the case that the nuclei of an atom will emit a neutron. A neutron has a charge of 0 and a mass of 1. This means that the atomic number for a neutron emission is 0 (bottom number) and the mass number is 1 (top number). We use the symbol n to display a neutron emission and the symbol with the numbers for it is shown below.
Gamma Rays
Sometimes atoms will have excess energy, and they get rid of this excess energy by emitting gamma radiation, which are gamma rays. Gamma radiation is usually emitted after the atom has emitted another type of radiation like alpha or beta radiation. Gamma rays are part of the electromagnetic spectrum and they have very short wavelengths and a very high frequency. Gamma radiation is just energy, which means that it has no mass and no charge; the atomic number and mass number for gamma radiation are both 0. The symbol for gamma radiation is γ and the symbol with the numbers is shown below.
Sometimes atoms will have excess energy, and they get rid of this excess energy by emitting gamma radiation, which are gamma rays. Gamma radiation is usually emitted after the atom has emitted another type of radiation like alpha or beta radiation. Gamma rays are part of the electromagnetic spectrum and they have very short wavelengths and a very high frequency. Gamma radiation is just energy, which means that it has no mass and no charge; the atomic number and mass number for gamma radiation are both 0. The symbol for gamma radiation is γ and the symbol with the numbers is shown below.
Gamma rays can penetrate far into materials and they can travel long distances in air (more than 1 kilometre). They are weakly ionising because they tend to pass through materials rather than colliding with the atoms that make up the materials. When they do collide with atoms, they do cause damage. Gamma rays are absorbed by a thick piece of lead or metres of concrete.
Summary
Here is a quick summary and comparison of alpha, beta and gamma radiation. Out of these types of radiation, alpha is the most ionising, then beta and finally gamma. Alpha radiation is the largest type of radiation, then beta and finally gamma (which does not have a mass as gamma radiation is just energy). Alpha radiation is the slowest moving radiation, then beta and gamma radiation is the fastest. Gamma radiation is the most penetrable and travels the furthest, then beta and alpha is the least penetrable.
Here is a quick summary and comparison of alpha, beta and gamma radiation. Out of these types of radiation, alpha is the most ionising, then beta and finally gamma. Alpha radiation is the largest type of radiation, then beta and finally gamma (which does not have a mass as gamma radiation is just energy). Alpha radiation is the slowest moving radiation, then beta and gamma radiation is the fastest. Gamma radiation is the most penetrable and travels the furthest, then beta and alpha is the least penetrable.