In the early 1900s, scientists were taking the first steps toward investigating the nature of radioactive decay. Radioactive decay is marked by the emission of energetic particles from atoms of an unstable material. Researchers detected three types of decay products, which all behaved differently: alpha, beta and gamma rays. Alpha rays had a charge of plus two, beta rays a charge of minus one, and gamma rays no charge at all.
Atoms are made of heavy, positively charged nuclei that contain protons and neutrons. Some arrangements of protons and neutrons are less stable than others. That is, some nuclei will spontaneously change, emitting an energetic burst that will most often consist of some combination of an alpha ray and a gamma ray or a beta ray and a gamma ray. Soon after the discovery of these rays, scientists realized the alpha ray and the beta ray were not "rays" at all, but were particles. An alpha particle is the same as a helium nucleus: two neutrons and two protons. A beta particle is an electron. Both alpha and beta particles can be hazardous to your health.
Unlike alpha particle and beta particles, gamma rays have no charge. They also have no mass. In fact, gamma rays are a very-high energy version of electromagnetic energy. The only difference between a radio wave, a light wave, an x-ray and a gamma ray is the amount of energy carried by the smallest packet of radiation, a photon. Radio wave photons have the longest wavelength and the lowest energy, while gamma rays have the shortest wavelength and the highest energy. Gamma rays are more energetic than x-rays, which means they are more dangerous than x-rays.
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