Description
Tom-the-Atom introduces to you, Mary and Henry, the concept of Radioactivity (different from reactivity, that we learned in Book 7. He calls in a heavy atom called Uranium or just U; from the Actinide family. He has 92 electrons in his shells and 92 protons in his belly. There are many Isotopes of Uranium, i.e., Atoms of Uranium but with different neutrons' numbers in their belly (giving different atomic weights). The isotopes of an atom have the same number of electrons and protons but a different number of neutrons. Accordingly, they have slightly different atomic weights, determined by the total number of protons and neutrons. Thus, isotopes are like twins; they look the same and have the same chemical properties, but they have slightly different weights. Because Uranium (U) has many neutrons and protons in the nucleus, the nuclei become unstable and can disintegrate. It disintegrates by emitting very energetic particles (radioactive disintegration).
