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).
Beta minus radiation occurs when a nucleus of an atom has too many neutrons. During beta minus 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 [minus] 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 minus radiation as β or e-. The two symbols and the numbers for beta minus radiation are shown below.
Beta plus radiation occurs when a nucleus has too few neutrons. During beta plus radiation, a proton turns into a neutron and a positron (which is known as a beta plus particle); the neutron is kept in the nuclei of the atom, and the positron is fired out of the nuclei at high speed. A positron is the antiparticle of an electron (essentially the opposite). Positrons are positively charged, which means that the atomic number is 1 (the bottom number). Positrons have virtually no mass, which means that the mass number is 0 (the top number). We can write a positron (or beta plus radiation) as β or e+. The two symbols and the number for a positron are 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.
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.
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.