The typical figure you're referring to, commonly known as the electromagnetic spectrum, arranges different types of electromagnetic radiation based on their wavelengths or frequencies. The arrangement is not arbitrary but follows a specific order that reflects the properties of these waves.
The electromagnetic spectrum begins with radio waves, which have the longest wavelengths and lowest frequencies among the various types of electromagnetic radiation. Radio waves are commonly used for communication, including broadcasting radio and television signals.
Next in the spectrum are microwaves, followed by infrared radiation, visible light, ultraviolet radiation, X-rays, and finally, gamma rays. Each successive type of radiation has progressively shorter wavelengths and higher frequencies compared to the one before it.
The reason alpha and beta radiation are not mentioned in the typical representation of the electromagnetic spectrum is that they are not part of the electromagnetic radiation itself. Alpha and beta particles are actually streams of particles emitted during certain types of radioactive decay.
Alpha particles consist of two protons and two neutrons (essentially a helium nucleus), while beta particles are either high-energy electrons (beta-minus decay) or positrons (beta-plus decay). Unlike electromagnetic radiation, which consists of oscillating electric and magnetic fields, alpha and beta particles are charged particles that have mass.
Due to their distinct nature as charged particles, alpha and beta radiation are not included in the electromagnetic spectrum, which represents different forms of energy carried by electromagnetic waves. Instead, they are often represented separately when discussing radioactivity or nuclear decay.