Write the name of any three radioactive elements.
Who discovered Alpha, Beta and Gamma radiations?
The nucleus of radioactive elements is unstable that's why they have the property of spontaneously emitting invisible, highly penetrating and high energy radiation. This property is called radioactivity.
Elements with a high atomic number such as uranium, thorium and radium.
Rutherford discovered that the radiation emitted by radium was of two types. They are called alpha and beta radiation. Willard discovered the third type, namely gamma radiation.