The nucleus contains protons (tiny particles each with a single positive electric charge) and neutrons (particles without any electric charge).
Orbiting around the nucleus are electrons (tiny particles each with a single electric charge).
(These are the moving particles which constitute the radioactivity measured by Geiger counters and the like.) The end result is stable atoms, but of a numbers of protons and electrons.
This process of changing the isotope of one element (designated as the parent) into the isotope of another element (referred to as the daughter) is called radioactive decay.
Thus it appears that God probably created those elements when He made the original earth.