I'm going on one, actually. My friend lives in an Orthodox Christian country and the girlfriend's parents are very conservative. In order to be allowed to continue go out long-term, the parents made them get married. They firmly believe in no sex before marriage and thought their daughter was still a virgin at 28.
I thiiiiiiiiiiiiink we might have allowed a day or two of recovery between them.
They're considered artificial because they aren't created naturally, at least on Earth. If an atom of a particular element arises from natural processes, it's natural. If humans arranged the protons and neutrons to form the atom, it's artificial. Some artificial elements can form naturally, but all of them are radioactive so the vast majority of the atoms of these elements would have decayed eons ago (since stars are the source of heavy elements), because of that it makes sense to consider them artificial on Earth.
It's "just" a case of smashing two very heavy nuclei together and hoping that most of them stick together and only a very small amount of protons and neutrons bounce off - or by blasting one very heavy nucleus with high energy protons to force them to stick to it.
Elements that, yes, could be (and some definitely are like Technetium) formed elsewhere. Easily may or may not be an accurate term. Elements up to iron release energy when fusing because they are increasingly stable. These elements are relatively easy to make in star cores, some just require bigger stars. After iron though there are too many protons and repulsive forces increase in the nucleus. You start to need to put in extra energy to fuse up to heavier elements. By the time you approach the 100's of protons, nuclei are unstable and the time it takes for atoms to spontaneously split starts to become very small as @Famine mentioned.
Yeah, it really would be.
Seems like the type of thinking that led to Cane toads, rabbits & foxes being introduced to Australia. All went on to be completely out of control pests.
IIRC Iron is the heaviest element that can be made in a Star, and everything from Cobalt to Uranium has to be made in Supernovae. Anything above Uranium (so Neptunium onwards) cannot be made by natural processes and has to be done by artificial, human designed methods. Plutonium can occasionally form in a bunch of specific-isotope Uranium that decays and reforms in the right way. These artificial elements usually have a very short half-life and emit alpha particles as the Strong Nuclear force begins to weaken as the number of protons and neutrons build up. All these new ones like Dubnium, Oganesson and Tennessine have really short half-lives of fractions of seconds for this exact reason. They've reached a point where creating new elements is more for fun than actual usage.
I don't know too much about nuclear reactor coolant but I do know there are two general types used; heavy water (deuterium oxide - a particular isotope of hydrogen) and borated water (water with boron).
