Q. Describe about Nuclei and Radioactive Decay?

Dalton consideration that atoms were unchangeable. But scientists in the late nineteenth century began to notice that some elements spontaneously emitted energy and particles. These emissions befall known as radiation. Elements that emit radiation are said to be radioactive. Quickly scientists discovered that radioactive elements changed into other elements subsequent to emitting radiation. Therefore atoms were not unchangeable as Dalton had thought.

Today we recognize that some nuclei are unstable and gain stability by emitting radiation. This process is called as radioactive decay.