Perhaps the simplest of all nuclear particles is the proton. This is a positively charged subatomic unit of mass which is found in the nucleus of all atoms. In fact each element is defined by nothing more than the number of protons present in its nucleus. A single proton all by itself is literally nothing more than a hydrogen atom. The very same element which helps make water, simply creating a chemical bond between two hydrogen atoms and one oxygen atom and presto, you now have a water molecule.
Protons can also be a form of radiation. In fact the solar wind is a very strong source of ionizing radiation which includes electrons showering our planet every day for which the earth’s magnetic field plays an important shielding role in focusing this radiation towards the poles of our planet.
Normally in nature, isolated protons are only found already bound to an electron making it a neutral hydrogen atom. Technically a hydrogen atom can lose or gain an extra electron making it an ion (an ion is just an atom with extra positive or negative charge). A positively charged hydrogen atom is really nothing more than an isolated proton because the neutral hydrogen atom is nothing more than just the positively charged proton surrounded by the single negatively charged electron cloud. Remove that single negatively charged electron cloud from the hydrogen atom and all you have left is the isolated positively charged proton.
When you heat materials, generally they go through the phase transitions from a solid to a liquid and then from the liquid to a gas. If you further heat the material, eventually the elements themselves will break up such that if the material were a molecular substance, the individual molecules would break apart into a mixed elemental gas. Heating this substantially further can eventually make the material so hot and full of energy that the very electrons themselves will be knocked off and generally unbound to the atoms resulting in a plasma such as that found in the sun. This plasma is what the sun continually ejects into the solar system which mainly consists of unbound protons and electrons.
Protons and alpha particles are also used in some very high tech cutting edge medical physics applications such as radiological oncology to kill cancer. Beams of protons can be focused to concentrate their dose into small defined volumes within a person. This can be done in such a way that the radiation dose would mold to a predefined and mapped out tumor as currently done by the MD Anderson cancer center in Houston. Alpha particles could also in theory be used in this way where an alpha particle is just the nucleus of a helium atom.
A natural helium atom would be composed of a nucleus containing two positively charged protons along with at least one neutrally charged neutron surrounded by a spherically symmetric cloud of two negatively charged electrons. Because helium normally has both the two positively charged protons and the two negatively charged electrons, the atom has no net charge and so is neutral. Because the laws of electrical attraction and repulsion state that opposites attract and like charges repel, the pair of electrons having an attraction to the nucleus keeps them attached to the atom even though they repel each other. The two protons in the nucleus are subject to additional strong nuclear forces as would be the neutrons. This is because without this additional strong nuclear force, the positive charge from the protons would push them apart and disassemble the nucleus back into lone neutrons and hydrogen. Adding neutrons into the nucleus is what provides that strong nuclear force to bind the protons together allowing all of the elements themselves to exist. Any nucleus having too many or too few neutrons relative to the amount needed only for stable binding will be radioactive. Each element has its own set of optimal numbers of neutrons to bring about stability of the nucleus so that in reality, the number of neutrons determines the type of radioactive particles will be emitted by the nucleus through radioactive decay.