The decay of radioactive parent nuclei to stable nuclei is known as radioactive decay or nuclear decay.
The type of decay depends on the type of radioactive particles emitted in decay.
Out of these three particles, protons and neutrons located at the center of the atom as a hard and dense part known as nucleus.
The rest of the part of atom contains negatively charged particles called as electron which balance out the charge of the protons and make the atom electrically neutral..
He concludes that uranium slats emitted some radiation like X-rays which can causes ionization in air.
For example; Uranium-238 disintegrated in to Thorium-234 by the emission of alpha particle which further changes in Protactinium-234 by the loss of a beta particle and anti-neutrino. Artificial transmutation The conversion of one element into another by artificial means is known as artificial transmutation.The atoms of radioactive elements on the emission of alpha particles and beta particles would change into atoms of another element.This change is spontaneous and occurs due to instability of heavy nuclei.There must be some nuclear force which maintains the existence of nucleus, because there is a repulsion force between positively charged proton which are collected in a small region of nucleus.If the number of proton is less in an atom, other forces can hold the protons together and atom becomes stables.