Is it possible for an element to emit more than one kind of radiation?
Yes, it is possible for a single element to emit more than one kind of radiation.
First, what's an element? It's a pure material consisting of individual pieces (atoms) which have a certain given number of electrons. This precise number of electrons (1 for hydrogen, 8 for oxygen, etc.) is what determines the chemical properties of the element. The nucleus of the atom contains protons (positive charge) and neutrons (no charge). An atom of an element is neutral and so has the same number of protons and electrons. However a heavy element might have variants which contain different numbers of neutrons (still equal numbers of protons and electrons). These different varieties of an element are called isotopes.
Now, nuclear radiation is a process whereby an atom's nucleus (which is in constant rotational and vibrational motion) emits some particle(s) and the remaining nucleus is in a lower energy state. If an excited nucleus exists, then it can emit a variety of particles and end as the same (but less energetic) or different nucleus SO LONG AS THE TOTAL ENERGY STAYS THE SAME. So, yes, a single type of element can emit protons, neutrons, alpha particles (2 protons and 2 neutrons stuck together), or gammas (1 unit of light), etc. depending on the details of the decay event. It won't always end up as the same element, but the total energy stays the same.
Mac Mestayer, Staff Scientist (Other answers by Mac Mestayer)